A Forum run by Enthusiasts of MidNite Solar

Given lithium battery's are now a viable cost effective option. Also now a practical option due to large cells format with equivalent capacity to the led acid cells on offer.

Are there any future plans for the classic range to offer a charge profile for lithium battery's?

I have had a very possessive experience for many years using lithium battery's to power my electric bikes, camper van and many other devices that were previously led acid. When my led acid battery's that power my off grid home are dead there is no question about them being replaced with lithium.

As it stands now before using my classic to charge by house battery's. I  experimented with it for a few days charging a small 40ah 12v lithium pack with a small 120w PV and its possible to tweak the led acid profiles to work with the lithium though a dedicated lithium profile would be much better.

Kurt.

Large Lithium type batteries pretty much already come with Battery Management System  (BMS) integration which is necessary to
balance all of the cells so that any one battery doesn't get hot or hog a charge.

What I've seen is that with this already in place, the controller simply has to either have the Classics' Absorb time
set to nearly zero OR, the BMS may have a control output that tells the Classic to stop and start its charging
via the Aux 2 terminal which now also acts as an input for this function.

Pretty cool, huh ??

We'll try to post some links for some of these as they pass by.  I have one or two somewhere already.

boB

Quote from: offgridQLD on January 01, 2013, 12:54:07 AM
.. When my led acid battery's that power my off grid home are dead there is no question about them being replaced with lithium.

My thoughts exactly, my 24volt 1200ah bank is now over 14 years in use, still going.. and will definitely be replaced with Lithiun Iron Phosphate batteries. Prices here are getting better by still about 4x price of wet lead acid although with an almost flat discharge profile down to 80% DoD I figure 500ah worth would be good.
And comes with a management system inc graphical software that manages charging inc logic controls to charging device.
I suppose this means a controller like the Classic will no longer do the battery state-of-charge management but will have its interface to the battery managed by the BMS. Most likely just an on/off function.

It looks like that is going to void using a pwm aux from Classic to manage current diversion to other devices such as heating elements and maybe also a Clipper to gradually slow a turbine.  ???

A Mk2 Classic optimised for use with LiFePO4 batteries ?

Dgd

Quote from: dgd on January 14, 2013, 07:25:57 AM

Quote from: offgridQLD on January 01, 2013, 12:54:07 AM
.. When my led acid battery's that power my off grid home are dead there is no question about them being replaced with lithium.

My thoughts exactly, my 24volt 1200ah bank is now over 14 years in use, still going.. and will definitely be replaced with Lithiun Iron Phosphate batteries. Prices here are getting better by still about 4x price of wet lead acid although with an almost flat discharge profile down to 80% DoD I figure 500ah worth would be good.
And comes with a management system inc graphical software that manages charging inc logic controls to charging device.
I suppose this means a controller like the Classic will no longer do the battery state-of-charge management but will have its interface to the battery managed by the BMS. Most likely just an on/off function.

It looks like that is going to void using a pwm aux from Classic to manage current diversion to other devices such as heating elements and maybe also a Clipper to gradually slow a turbine.  ???

A Mk2 Classic optimised for use with LiFePO4 batteries ?

Dgd

Depending on the BMS type used, I would think you should still be able to use diversion to use that extra energy.

The thing that would change would be the diversion voltage set point.  For instance, if the BMS doesn't
care what you give it after the battery is full, divert at Absorb.

Or, maybe divert at just slightly over the battery open circuit voltage.

As soon as you start diverting at lower than the battery's resting voltage, it won't be full anymore.

boB

Quote from: dgd on January 14, 2013, 07:25:57 AM

A Mk2 Classic optimised for use with LiFePO4 batteries ?

No,  just a firmware update! ;D

Quote from: mtdoc on January 14, 2013, 02:21:11 PM

Quote from: dgd on January 14, 2013, 07:25:57 AM

A Mk2 Classic optimised for use with LiFePO4 batteries ?

No,  just a firmware update! ;D

Although there can be no doubt the present Classic is easily the best mppt controller available (as was the MX60 in its day),  it may well reach limits that a firmware update just don't fix  :o

Changes in battery technology such as LiFePO4 sort of remove all battery management from an mppt controller. The design of the Classic and its forebears seem closely linked to the 'older'  battery types.
Gone will be EQ, Absorb and Float as we understand them (also the large heavy banks of batteries making noxious fumes and needing regular maintenance).

Maybe it's time now to start looking at the next gen of Classic?  Personally I would like to see the whole user interface updated, this meaning perhaps another CPU in the design that provides the sort of interfaces we all now expect.. Such as
Video and keyboard interfaces (USB) and then get rid of that god awful MNGP display and its pokey rubber buttons interface. The firmware has the vid/kb drivers built in.
Networking WIFI as well as the Ethernet interface.
Serial USB that can provide power to other devices
Some decent logging storage based on removable  memory not embedded flash.
More than two configurable I/O controls   8?

Dgd

wait wait wait,

LiFePO4 cost competitive with lead acid?

Where?

Do tell, please!

I've got some medium scale liFePO4 stuff on my bike, and it's really agreeable.
but i never ever considered it for PV solar use, way too spendy.

Quote from: dgd on January 14, 2013, 04:09:43 PM

The firmware has the vid/kb drivers built in.

Video/Keyboard drivers ????  Where is this ?

boB

Quote from: dgd on January 14, 2013, 04:09:43 PM

Quote from: mtdoc on January 14, 2013, 02:21:11 PM

Quote from: dgd on January 14, 2013, 07:25:57 AM

A Mk2 Classic optimised for use with LiFePO4 batteries ?

No,  just a firmware update! ;D

Although there can be no doubt the present Classic is easily the best mppt controller available (as was the MX60 in its day),  it may well reach limits that a firmware update just don't fix  :o

Changes in battery technology such as LiFePO4 sort of remove all battery management from an mppt controller. The design of the Classic and its forebears seem closely linked to the 'older'  battery types.

Sorry but I disagree.  I see no reason the current excellent Classic could not have a LiFePO4 charging profile added to it with a firmware update-but I'm sure Bob or Ryan can correct me if I'm wrong.  Charging lithium batteries is really not that different.   Just no need for absorb stage and some tweeks in voltages.  My LiFePO4 charger for my 16s(48V) 20 AH  eBike battery is not that complicated.  Lithium batteries still use a bulk stage and a small float current to prevent spontaneous discharge (which is very low anyways.).  Of course no Equiliization - just as is true for AGMs.  Even with current firmware the Classic can be set up just fine to charge LiFePo4s.

The current Classic is just over 2 yrs in production!.  It it still a baby. The advantage of upgradable firmware - I think would mean  its lifespan should be much longer than even the venerable MX60!


I imagine there will be more small hardware tweaks but total redesign?  !!!   I'd prefer the good folks at MN concentrate their hardware development efforts on their current projects - "The Kid" ,  Inverters, etc.

Of course eventually there will be a new classic design - but  soon????


Besides - my 3rd classic is still in it's box! ;)

Quote from: mtdoc on January 14, 2013, 05:16:32 PM

Quote from: dgd on January 14, 2013, 04:09:43 PM

Quote from: mtdoc on January 14, 2013, 02:21:11 PM

Quote from: dgd on January 14, 2013, 07:25:57 AM

A Mk2 Classic optimised for use with LiFePO4 batteries ?

No,  just a firmware update! ;D

Although there can be no doubt the present Classic is easily the best mppt controller available (as was the MX60 in its day),  it may well reach limits that a firmware update just don't fix  :o

Changes in battery technology such as LiFePO4 sort of remove all battery management from an mppt controller. The design of the Classic and its forebears seem closely linked to the 'older'  battery types.

Sorry but I disagree.  I see no reason the current excellent Classic could not have a LiFePO4 charging profile added to it with a firmware update-but I'm sure Bob or Ryan can correct me if I'm wrong.  Charging lithium batteries is really not that different.   Just no need for absorb stage and some tweeks in voltages.  My LiFePO4 charger for my 16s(48V) 20 AH  eBike battery is not that complicated.  Lithium batteries still use a bulk stage and a small float current to prevent spontaneous discharge (which is very low anyways.).  Of course no Equiliization - just as is true for AGMs.  Even with current firmware the Classic can be set up just fine to charge LiFePo4s.

The current Classic is just over 2 yrs in production!.  It it still a baby. The advantage of upgradable firmware - I think would mean  its lifespan should be much longer than even the venerable MX60!


I imagine there will be more small hardware tweaks but total redesign?  !!!   I'd prefer the good folks at MN concentrate their hardware development efforts on their current projects - "The Kid" ,  Inverters, etc.

Of course eventually there will be a new classic design - but  soon????


Besides - my 3rd classic is still in it's box! ;)

The Classic does not need a separate LiFePo charging profile.   Batteries with the BMS (which is necessary anyway) mean that it already works for these.  You will have to change the Absorb time or maybe use the Aux 2 input force to stop charging function from certain BMS's.

Neither the Classic, or any other regular MPPT controller, will be able to do the individual 3V LiFePo cell balancing and management to take over the BMS that is built into the stuff you can buy these days.  All the Classic has to do is to supply the power and voltage to the battery "system" already there.   

boB

but but but,

Where are these cost-competitive (with lead-acid) LiFePO4's?

Quote from: cpm on January 14, 2013, 05:31:17 PM
but but but,

Where are these cost-competitive (with lead-acid) LiFePO4's?

Yeah, that I have not heard

I'd like to know, too...

boB

Quote from: boB on January 14, 2013, 05:15:23 PM

Quote from: dgd on January 14, 2013, 04:09:43 PM

The firmware has the vid/kb drivers built in.

Video/Keyboard drivers ????  Where is this ?

boB

..was referring to a new Classic with the appropriate drivers to drive screen and keyboard directly
Dgd

Quote from: boB on January 14, 2013, 05:27:23 PM

Neither the Classic, or any other regular MPPT controller, will be able to do the individual 3V LiFePo cell balancing and management to take over the BMS that is built into the stuff you can buy these days.  All the Classic has to do is to supply the power and voltage to the battery "system" already there.   

boB

Yes. Thanks. The functions of a BMS are different than the functions of a charger.  As you say most of the large prismatic  LiFePO4 packs are sold with BMS included. There are several separate BMS systems marketed as well. 

Of course if  Midnite wants to get into the BMS business - I'm sure you could improve on current designs.. ;)

I agree with dgd and others - I think LiFePO4 will likely be the RE battery chemistry of choice eventually....

Quote from: cpm on January 14, 2013, 05:31:17 PM
but but but,

Where are these cost-competitive (with lead-acid) LiFePO4's?

Depends where you are, I suspect Kurt in Oz gets similar pricing but here in New Zealand one of the local PV/battery/controller suppliers has LiFePO4 high capacity batteries.
Individual cells are available in 100, 300, 500, 750 and 1000ah capacity 3.3v per cell
A nominal 12volt battery with 4 cells is Nz dollars 999 - about USD 750 - for 100ah and NZD 5000 for 500ah.  24v 500Ah containing 8 LiFe cells would cost about NZ$10k but price reduces as battery config gets larger.
The replacement cost of my six Century Yaesu 1100ah 4v cells at NZ1750 each is about Nz10k.
Maybe lead acid batteries are more expensive here because they have to be imported from Oz or USA.
The LiFe come from China, I think the large LifePO4manufacturer BYD Co.

I'm waiting on pricing / availability of the 1000ah cells as the largest available ex-stock now is the 500ah. However LiFePO4 pricing is just too attractive to stay with lead acid at battery replacement time.

Dgd

Interesting,

Here, the only 500ah LiFePO4 I could find was $700 per cell, no BMS
or, I could buy a 12v (4cell) 500ah for $6K

in contrast, a pair of 435ah L16s would be a fraction of that. maybe 1/8th or so.
I think our lead acid costs are similar, Li, not so much. still very spendy here.

Unless someone here (in the US) knows something very interesting. :)

thanks.

Quote from: mtdoc on January 14, 2013, 05:16:32 PM

Quote from: dgd on January 14, 2013, 04:09:43 PM

Although there can be no doubt the present Classic is easily the best mppt controller available (as was the MX60 in its day),  it may well reach limits that a firmware update just don't fix  :o

The current Classic is just over 2 yrs in production!.  It it still a baby. The advantage of upgradable firmware - I think would mean  its lifespan should be much longer than even the venerable MX60!

Oh please I hope that is not the case. Venerable as the Classic is it already is a somewhat 'dated' design. Two years may be baby time in the renewable energy business BUT not in the electronic design/Computing or software development areas.
That is where I suggest redesign needs doing.  The Classis is damm good at what it does with mppt but is woefully lacking in world/user interfacing. I'm not saying the current Classic is defective and I agree its the best available now but...

Quote

I imagine there will be more small hardware tweaks but total redesign?  !!!   I'd prefer the good folks at MN concentrate their hardware development efforts on their current projects - "The Kid" ,  Inverters, etc.

That's probably economic reality hopefully made easier now that Outback have shot themselves in the foot with their exit from USA.

Quote
Besides - my 3rd classic is still in it's box! ;)

Shame on you  :)  but maybe not such a bad idea.. Security,redundancy,lightening strike insurance,..

Dgd

Im planning in 6-7 years time when the flooded battery bank get retired.. LiFePo4 would be a ideal replacement.. by then should get 10WHr per $1 ..with the dropping pricing ?

Quote from: dgd on January 14, 2013, 06:40:04 PM
Venerable as the Classic is it already is a somewhat 'dated' design.

:o

QuoteTwo years may be baby time in the renewable energy business BUT not in the electronic design/Computing or software development areas.

Exactly  ;)

Quote

Security,redundancy,lightening strike insurance,..

No, microhydro  - hopefully to be added this summer...

Just in case anyone was following this thread, on the news of 'affordable' LiFePO4,

i did find something, because it just seemed too good to be true,

I found this battery:

http://www.balqon.com/store.php#!/~/product/category=3262346&id=13936727

Balquon High Capacity - Lithium Battery 12 Volt, 700 Ah (LiFePO chemistry)
$2 640.00

I've got an outback gtfx 3524 (sadly) still sitting in it's box along side my classic 250, also sadly sitting in it's box,
a pair of these would fit me nicely, if I can actually get them. There's the rub, eh?
And yeah, this would be cost-competitive with lead acid. A bit more $$, but should last much longer, and less hassle.
I'm using smaller LiFePO batteries for other stuff, and am very happy with them.

hi density power

Nominal Capacity  :700 AH
Operating Voltage:11.2V~16.0V
Weight:412 lbs +/-3 lbs
Dimensions:25.25"×11.75"×16.5"  ( that is similar to 2 x 2V of my 900ah AGM cells)

so 2.8 cubic feet weighs 412 pounds.  Who can lift that weight...alone?

well, the 412lb package is pretty daunting, true enough.

I recently installed my new soapstove woodstove by myself, and it
tipped the scales at ~700lbs. I honestly was worried while crossing the
floor with it on the way to the hearth.

:)

I think I could manage it, esp if I don't have to it again in my lifetime.

CPM, I speed read your post and missed the first 'h' in the last word.. ???..thought you almost went through the floor :'(   then I had to reread it  ::)

Quote from: cpm on January 15, 2013, 07:40:21 PM

I've got an outback gtfx 3524 (sadly) still sitting in it's box along side my classic 250, also sadly sitting in it's box,
a pair of these would fit me nicely, if I can actually get them. There's the rub, eh?
And yeah, this would be cost-competitive with lead acid. A bit more $$, but should last much longer, and less hassle.
I'm using smaller LiFePO batteries for other stuff, and am very happy with them.

I just had the same issue, high capacity 700Ah and 1000Ah LiFePO cells are priced and advertised BUT will be a 4 month wait before any are available.
The only nice part of the wait is that the importer assures me the price will be significantly lower.

So I have obtained 8 by 200watt cells with BMS (for 24v), ordered a Classic 250 and four 230watt PVs. Just need to find a small Magnum Sine 230V inverter and then I can really test these batteries.  :P
Just thinking that if the Classic arrives soon then I can be in that exclusive Classic owners club who keep their Classic 'sitting in it's box'   ;D

dgd

Quote from: dgd on January 16, 2013, 12:39:01 AM

Just thinking that if the Classic arrives soon then I can be in that exclusive Classic owners club who keep their Classic 'sitting in it's box'   ;D

dgd

Come on guy's At least taker Her out of the box and hang her on the wall in the Living room or something? Maybe plug a wall wart into Battery in and have the Blinky LED's going for ambiance.  ::)

Ryan

Quote
So I have obtained 8 by 200watt cells with BMS (for 24v), ordered a Classic 250 and four 230watt PVs. Just need to find a small Magnum Sine 230V inverter and then I can really test these batteries.

Interesting, where did you get them?

That outfit I posted claims to have 12 or so 1000ah cells in their clearance section, ready to ship. 45% below the regular price.
but there is no mention of the BMS for them.

Quote
Just thinking that if the Classic arrives soon then I can be in that exclusive Classic owners club who keep their Classic 'sitting in it's box'

Yeah, we need a 'sitting in box' registry.

Quote
Come on guy's At least taker Her out of the box and hang her on the wall in the Living room or something?

Don't imagine that it hasn't occurred to me already.. :)

Quote from: Halfcrazy on January 16, 2013, 06:35:34 AM

Come on guy's At least taker Her out of the box and hang her on the wall in the Living room or something? Maybe plug a wall wart into Battery in and have the Blinky LED's going for ambiance.  ::)

Ryan

I agree. The box is kind of sexy but the Classic itself is really cool looking. Like Ryan says, hook it to a walwart, set the LEDs to "obnoxious" and enjoy the show!  ;D

I would like to get one for my turbines but after this summers upgrades it will be awhile before that happens.

And now you evil people have me drooling over Lithium Batteries.  :(

This addiction never ends or is satisfied! 8)

Just from here.

Tom

Quote from: TomW on January 16, 2013, 12:04:27 PM

Quote from: Halfcrazy on January 16, 2013, 06:35:34 AM

Come on guy's At least taker Her out of the box and hang her on the wall in the Living room or something? Maybe plug a wall wart into Battery in and have the Blinky LED's going for ambiance.  ::)

Ryan

I agree. The box is kind of sexy but the Classic itself is really cool looking.

Her? sexy? I think you both might need to get out more often  :D

Quote
And now you evil people have me drooling over Lithium Batteries.  :(

This addiction never ends or is satisfied! 8)

The evil genius here is the Midnitesolar marketing dept. These end users so committed they buy Classics to 'keep in its box'  :o

dgd

More blatant topic drift..

Ha, why would I want to get out more? I live exactly where I want, am well stocked with supplies, food, ammo and the like. Nobody bothers us, an advantage of having a large property with  a private shooting range out back.

@ 60 "Sexy" has a broad meaning for me.

Have you seen the Classic box graphics?

Tom

Sorry I started the thread then forgot about it  ::)

large format lofpo4 sells are available 400ah - 1000AH is common and easy to obtain. Even larger is available!

What you need to look at when comparing a Lifepo4 cell to a led acid is usable capacity. Given most of us only use 10 - 30% of our led acid battery's capacity our 1000AH led acid cell is effectively a 100 - 300AH cell . Yet you need large cells to cope with high C loads as led acids have terrible C rating.

400Ah of lithium will outperform 1330AH of lead in both, C rating, usable capacity, price, maintenance, cycle life and the big one charge efficacy! just think if you go away for a month on your cells rest at 50% soc (no ill effects with lithium if they sit around at less the 100% soc actually its healthy for them) oh the joy  ;)

my plan (when the led is dead) Is to replace 1330AH at 48v on paper 60kwh of flooded lead acid (That at the moment is subject to a 6kwh load 10%  DOD each day) and replace it with 400AH 48v 20kwh of lifpo4 with a 30% 24hr DOD each day to cover the same load.

In Australia 1330Ah at 48v of Exide 2v industrial flooded led acid cells the same as I have now cost roughly $15,000. The replacement 400ah - 48v lifpo4 pack including BMS and cell straps is roughly $10,000 and are available now.

A member of another local forum I post on just replaced his led acid with the same lifpo4's I'm considering and is very happy with them charging from a old outback charge controller with some adjustments to the charge settings.



Kurt

I am surprised at so many people still recommending BMS for Lithium (LiFePo4 Chemistry) batteries. As demonstrated for several years now, via Jack Rickard at EVTV, in electric car conversion usage, as long as you bottom balance the cells initially, they remain quite close balanced by themselves. I suspect that an EV would be much harsher on them than usage in Households.

My own system shall consists of 16 cells (3.2v/ 100Ah each) in series.

I'll let you know if I burn my 'tool-shed' down! Though doubtful as they can comfortably output at 3C (300amps). I'm not sure what I'd be up to pulling that much!

ps. CALB LiFePo4 cells are going for around $1.50 an Ah. Not bad.

Yes I am very familiar with Jacks methods.

  It's a little different charging your car vs powering a house. Charging  your car perhaps once a week at a set predictable amp level on a ac wall charger . Two things I can see with his methods is he tinkers a lot with his car but how much day in day out use his car get is questionable. I doubt he experience is from consistent cycles over many years. At this stage he is getting away with it as its true the cells will remain relatively balanced.

Its a bit like having a hose filling  a big empty swimming pool and jumping up and down in it telling everyone your shorts aren't wet yet. Just give it some time to fill up and your shorts will be wet. Cycle your cells every day over say 10 years and things could be a little different . Small discrepancy's do add up. Remember a BMS isn't just for balancing if and when its needed its there as secondary (last resort) protecting for over discharge and over charge.

That said I have a small 12v 20ah lifpo4 pack that's being charged by a primitive plasmatronics PWM charger and  120w pv. Powering a small compressor fridge for almost a year with no bms . Its set to slightly undercharge the cells so the balance stays in check relatively well by its self. The cells them self are over 5 years old and couldn't be happier with them.

Kurt

Hey Kurt. Nice reply.

I have been using my off-grid system (powering my tiny house - 12ftx14ft and 14ft ceilings) for 202 days. My battery bank is 5kwh - 100aH CALB CA series - 16 cells. Typically I use little over 2kwh a day. However, if I am feeling wild, I will watch a bunch of TV and possibly even use the 1500watt electric heater during the sunny Colorado days. Then of course it could be 8KWH/Day! I make sure to turn off the heater early enough to make certain the batteries are charged, but even with the load, they float happily. I have a 2000 watt array and plenty of intense sunlight on the mountain. Plus the heater actually cycles on and off a bit.

I have been pretty diligent about checking out the voltages on each cell in various charge states. In the morning when they get 40 amps at a shot, or when they float, or when they rest at night.

I'm seeing at rest they are 2-4mv apart and in full charging possibly up to 15mv. They are really close.

However, as you noted being familiar with Jack's method, I intentionally undercharge them. I recently bumped up the voltage parameters but for the last couple weeks they have been holding those ranges above with the settings as follows.

No equalize, Bulk @ 55v, Absorb is 15min @ 55, Float @ 54.5v 

Most of the day is spent floating with a few hundred watts coming in to compensate for loads and the tapering of charge.

Once the Charge controller goes into resting, the voltage drops to around 53.4.

One thing I need to add to my setup is a coulomb counter so I can read exactly what I am taking out of the bank in the evenings to see what portion of my daily usage is straight battery without float.

Then I can figure out the typical DOD %. Though at 2-3 per day either way it isn't more than the 80% and 3000 cycles they claim.

Quote from: Cniemand on January 29, 2014, 09:15:42 PM
One thing I need to add to my setup is a coulomb counter so I can read exactly what I am taking out of the bank in the evenings to see what portion of my daily usage is straight battery without float.

Then I can figure out the typical DOD %. Though at 2-3 per day either way it isn't more than the 80% and 3000 cycles they claim.

Cloud;

Thats a new one on me (coulomb Counter). I believe a Whizz Bang jr would be a good match for that. It connects across the shunt from a Classic and keeps track of the net amps in the system on the Classic.

I was going to find you a link but I cannot find it on their products page? Maybe they are not in full production yet?

Just FYI

Tom

Ryan sent me the link to the Whizz Bang Jr:

http://www.midnitesolar.com/productPhoto.php?product_ID=519&productCatName=Charge%20Controllers%20-%20Classics&productCat_ID=21&sortOrder=9&act=p (http://www.midnitesolar.com/productPhoto.php?product_ID=519&productCatName=Charge%20Controllers%20-%20Classics&productCat_ID=21&sortOrder=9&act=p)

Mine works treat and it even includes a State of Charge readout on the Classic and eventually  the mymidnite logging site.

Good luck with your system.

Tom

Thanks, Tom. I was seriously looking at it last evening. People seem to be happy with it and for $80 between the shunt and Whiz, it is pretty inexpensive compared to the other meters or House monitors. :)

Boy, this thread just goes all over the place.
First of all I would like to thank all of you who purchase Classics and keep them in the box. We report very few problems with those units.
The Classic charges Lithium batteries all the time. boB even added a special mode on one of the aux inputs that shuts the charge off when the battery management sends a signal to do so.
I think anybody charging Lithium batteries without a BMS better have the batteries in a fire proof room! Some of the BMS systems aren't so fool proof either. Ask Boeing.
Lithium is getting more competitive, but you won't finding me using it anytime soon. Too scary and still too expensive. We do like those brave enough to do it though. We are supplying a bunch of stuff to Solar City who are using a large Tesla battery for AC coupling. We had to do some special things though to keep from tripping a breaker or fuse in the battery pack. We will also be working with Juice Box battery company. There are numerous companies out there messing around with the Classic and Lithium. Some in the military.
I don't understand the comment about user interface not being up to date? Most people don't fiddle with their controller like some of you all do, but if you want to use a keyboard, why not hook up to the local app?
We should be releasing an app shortly that will allow the local app to be used on your cell phone. It will also have the new state of charge meter.
I might even be tempted to look at my own system once in a while that way?

I think anybody charging Lithium batteries without a BMS better have the batteries in a fire proof room! Some of the BMS systems aren't so fool proof either. Ask Boeing.
Lithium is getting more competitive, but you won't finding me using it anytime soon. Too scary and still too expensive.

If you take a moment to think about it lithium ( there is quite a few different types of lithium chemistry ) there are millions upon millions of lithium powder devices on charge or in used in our homes every day. The laptop I am typing this response on is powered by lithium batteries. The phone in your pocket (inches away from your crown jewels all day ;) ) Is power by lithium batteries. My EV car that is parked down stairs in the garage under my bedroom charging all night is powered by lithium. It's nothing new and just like lead acid it's safe if used and charged properly. ( Boeing didn't charge or use it properly and they used the most unstable form of lithium there is)

Don't tell me you have never heard reports of a lead acid battery exploding or catching fire when abused in some way beyond its specs.

So for now lets talk about the most commonly used form of lithium for offgrid applications. Lifep04 cells usually in large prismatic form. I want to talk about the BMS- Battery - Monitoring- System for lifepo4 cells as its often misunderstood what its there for and if one is needed.

There is only two things that can go wrong with a lithium battery ..over charge and over discharge.  So all you need is a way to control this. A good charge controller like the classic range is reliable enough to cover this need 99.9% of the time I can set a maximum charge voltage a tapered current end amps and a float voltage. That will keep the batteries conservatively within spec. I need some way to disconnect the batteries from the load if the voltage drops bellow a set point. This could be done a number of ways through  a inverters programming or some other component already in the system than can activate a large contactor and break the load based on low voltage. So with the above in mind most of us already have all the control we need for a lithium battery in our old lead acid system. This could be called a BMS its monitoring the battery and acting on it (controlling the change and isolating the load if needed) .

Now we get onto balancing the cells (led acid guys call it EQ) potentially example 16/400A cells in a 48v lifepo4 system could potentially drift away from one another over time. Honestly with the kind of charge/discharge loads a offgrid house puts on them they will stay in balance very well on there own. Particularly even more so when your operating them in the middle of there SOC range (not fully charging them and not fully discharging them).

That said on cell balancing modules are inexpensive and once a multi cell battery pack has been initially (rough balance) usually don by hand using a load like a light globe or large resistance load  and jumper cables to get all the cells close to one another (wiring all the cells in parallel  for a day or two before installing them can do the same thing)  the little on cell shunts can take over and  bleed of small discrepancies between individual cells if and when they arise. Remember the world doesn't stop spinning or battey blow up if you have a small discrepancy between cells it would have to get really out of whack over a long period of time to be a issue. Though one will find after the initial balance the cell top balancers are not often active as there just isn't any imbalance to correct. The same on cell units can also report the individual cell voltage to a device that can trigger that big contactor I mentioned before killing the load and or charge in a (EMERGENCY SITUATION!) Its basically like a fuse for your battery last resort if everything gets so out of whack. (in normal operation the BMS just sits idle doing nothing)

So to sum up a charge controller like the classic is more than capable of keeping a lifpo4 bank in check if you set it up properly. The BMS will not become part of the picture 99.9% of the time its just there as a last resort (say your classic went crazy) The BMS has its back to activate that big contactor. And finally if they both failed its not going to burn your house down with lifepo4 the result wouldn't be any worse than if your charger went crazy on your led acid . You might have some swollen sick cells just as you would if you boiled the crap out of your led acid.

As for the cost you need to consider cycle life, C rating (silly to have 1000AH of lead when you don't need the capacity but you need the size just to cover big loads due to its rubbish C rating) You also need to consider cycle life based on usable capacity you can use 80% of the capacity of a lifepo4 cell and get 3000+ cycles led acid its 10-20% . The final big advantage particularly when charging from PV is lithium batteries don't need to be fully charged each day. Infact they like to be stored long term at 40 - 50% soc . The same cant be said for lead acid.

Lithium is to lead acid what digital cameras were to Kodak!....lead is dead.

Kurt

i agree. i my self have done some research on lithium to see if it is feasible in the long term, and it is but not right now.In my opinion there is still a little more work/or a lot more , to be done on lithium for large battery banks(like in off grid systems) . I think most folks out there are not lithium literate and definitely not lithium literate about the types of lithium there are.

"In my opinion there is still a little more work/or a lot more , to be done on lithium for large battery banks(like in off grid systems)"

What work is it that you think needs to be done?

Kurt

Quote from: offgridQLD on March 06, 2014, 09:12:12 PM
"In my opinion there is still a little more work/or a lot more , to be done on lithium for large battery banks(like in off grid systems)"

What work is it that you think needs to be done?

Kurt

I was wondering that too. AFAIK the larger capacity Lithium cells are extremely stable and if configured in a single string then cell imbalancing becomes a minor issue.
Earlier large capacity Li banks usually consisted of several to many strings of smallish capacity cells that created some serious issues with string balancing and could lead to individual cells failing.  Hence those important Li BMS systems that monitored and applied charges to individual cells as needed to keep all in balance.
It seems the most important issue with a single string larger capacity LI bank is having some sort of battery monitor so that charging  replaces what is used - since Li cells stay same voltage down to 80% discharged.
I have used a 48v 300Ah LiFeYPo4 single string bank of 16 cells for near a year without any problem.
Sold these and now witing on 48v 400Ah CALB cells to arrive from China.

The Classic with WBjr and SOC processing looks good for Li cell management.

dgd

well some one answered before me cell balancing mainly and safety to an extent while i understand that all battery technology can be safe/unsafe , i think some more work has to be don't on safety features until regular folks are educated fully about lithium.Just my opinion though i am no expert in the field.

Oh and the price vs the years of service does not really play out too good even with the advantages of lithium.I would just say it may be great but we are not quite int the position we would like to be with lithium.Prices for lithium need to come down in order for us to get to that position.

Well im as enthusiastic as the next guy about better battery technologys, and the next bank will likely be LFP, but id tend to agree on the not ready for prime time.

If you hang around the forums even a few days youll come across a worrying trend of folk who dont understand even the lead acids they have and are treating them absolutely shockingly.

So what can happen with lithium, whats the worse case? Both Pb and Li are capable of thermal runaway, but i would say from my reading that lithium in general is more vulnerable. The combination of a reactive elements and volitile organic electrolytes does have potential for drama.

The way to send a LFP into thermal runaway is to place too high a load on a charged cell, such that the temperature cant escape fast enough.  More temp, more current, more temp etc.
The videos ive seen of  fire department experiments short circuiting CALB cells isnt actually that dramatic, sure theres a big bang, lots of smoke and (poisenous) gases, but no fire as such.

Then theres over discharge. Over discharged cells tend to short circuit, On its own its only going to kill the cell. But a cell parelleled with others as is common with LFP,  will short  its mates and send them into thermal runaway.

...photos of the batteries suggest that such thermal runaway is practically designed
into the 787 batteries. That’s because the eight notebook-sized lithium-ion batteries
are packed next to each other in a sealed metal box.

Those batteries are prone to heat up and the 787 battery design makes it difficult
to vent that heat. Boeing told regulators that it had implemented a computer
controlled system to stop such overheating. ...Needless to say, this system did not
work with the flights that prompted regulators to ground all 50 aircraft.
-- http://www.forbes.com/sites/petercohan/2013/02/06/
   thermal-runaway-in-787-dreamliner-batteries-must-be-stopped/


tldr: lots to go wrong

Your not going to use the same cells in your home as they did in that Jet in your offgrid house ( there is more to that story than you first think).

Lifpo4 is what 99% of people will use and it's a different beast altogether. Unless your planning on  running a aluminium smelter in your kitchen. Then Your not going to ever have a load in a off grid house that will send a lifpo4 cell into thermal runaway.

My 16kwh lithium battery in my car gets 50,000w discharge loads! followed by 25,000w recharge from regen and 40,000w when its being fast charged and its a factory OEM setup that's warrantied for 10 years. How many offgrid homes are going to install a 16kwh bank (small by offgrid house standards) and have a AC inverter that can suck 50,000w from it? Or a PV array that can pump 25 - 50,0000w. and even if they did thats fine because that's the kind of input/output that lithium battery's can handle and do it safe in a OEM warrantied car like mine douse every day.

Thermal runaway?  load your 16kwh lead acid bank up with a 50kw load or charge and you will see a great example of thermal runaway  ;)

Pile of mutton lead on the floor.

yes i agree but still the price is a very big factor.

Kurt, your last posting had me cracking up!

You can toss my name as another lipo4 user that hasn't had any issues with them. I've had the system up 10 months now in a full off-grid usage. I've been here daily. The cells just sit there all balanced amongst themselves.

The Classic is a great controller for Lithium with its ability to custom set the voltages and turn off EQ etc.

As stated many times earlier. It is comes down to using the middle of their charge. Under and Over voltage is the bad area. Through cutting off those points on the Charge curve where it either plummets or shoots off, you save them.

The capacity remaining at those ends is very little anyhow. You end up loosing very little capacity but greatly increase life-times of the bank as well as leaving them in the safe zones.

Another note, it is easy to string the individual cells in series to get your 48v and never need a parallel connection.

can anyone here state the price range for the lithium batteries they have been praising so much.I definitely know the benefits but the lithium but those i have came across are just too expensive or they are not available where i can purchase them.So please recommend a brand ,place of purchase and price range.

I am using CALB cells. 16 - 100aH cells. I purchased mine from the evtv store in Missouri. Each cell was USD$150. Thus the 48v 5kwh bank was USD$2500 with shipping.

Your milage may vary of course. :)

so each cell is about 3.1v or so

48 volt nominal. The Lifepo4 cells are spec as nominal 3.2v. I charge them to 3.5 each. At 3 volts you should consider them fully discharged to save them from plummeting.

I think the actual spec is between 2.5 and 3.65v.

I have mine programmed to charge to 55v then float at 3.34v per cell which is their resting voltage.

ok kool, But what i noticed is the there aren't any or there are very few US suppliers of these batteries ,I have source these or similar from Australia.Shipping cost is a killer

True. Although, to be honest. Solar is pretty inexpensive for what it is already. My entire system of 2000w and lithium batteries which quality componenets such as 200v MNCC and outback 3600 watt inverter was only USD $7200.

I guess I could have cut some money off through using lead but I didnt want the maintenance and venting issues.

total cost $ just $7200?

While we are at this can i be intrusive and ask how much you discharge your batteries when the sun is not shining?

At night. Depends how much hot tea im drinking (electric kettle) and how much netflix im watching on the 42in tv or if Im just using the led lights and surfing the internet.

These days, between 6pm and say 11am when it kicks back to float, shows 2.5 to 3kwh. Mostly on the lower end.

80% DOD in the bank is 4.1kwh. So I guess I am using on average at night 50-60%

If it is a spell of cloudy/snowy days I'll throttle back but that is rare up here in Colorado.

I've never had to use a generator, which was my point of having so many panels.

My total cost for all the components was $7200 with shipping and taxes applied. No permit costs or electrician.

$2500 of which was the batteries.

So, 8 panels, a midnight solar 200v charge controller, an outback 3600 inverter, a midnight solar lightning arrestor, and a midnight solar two string combiner box.

So, when you factor in the wiring and diy racking used. More $7500.

Nice i use approximately the same as you but as with my battery bank going below the 80% soc means reducing the battery bank life.I read in an article that lithium can be discharged at about 50% Dod .Guess a guy like you can only verify that

that's not bad i bought my equipment in pieces and has reached that amount and i am still at 12v ,really want to switch to 48v,but cannot do that until i raise funds for 48v inverter or be forced to buy on when my 12v Xantrex dies.

Actually, that is where others talk about the savings of being able to use much smaller battery banks and get the same usable capacity.

The Calbs Lifepo4 battery chemistry has data showing 2-3000 cycles with 80% DOD regular usage.

I think, Kurt, was talking about how you can essentially cut your bank to half the size needed in Pb when switching to LFP4 batteries.

ok so its not just any lithium then?

Lithium batteries vary greatly. That is why people are fearful of them. Such as lithium cobalt or lithium manganese with catching fire. Those early laptop batteries.

I'm not aware/have direct knowledge of the other lithium chemistries. The Lithium Iron Phosphate LiFePo4 ones are those I use. They are pretty stable when kept in their voltage ranges.

They are the ones that show 2-3000 cycles for 80%dod. I believe that the data suggests the cycle life changes quite a bit better when only using say 70% or less.

thank for the info

Any updates on the Lithium?  Prices from http://www.balqon.com/energy-storage/ (http://www.balqon.com/energy-storage/) seem very reasonable.

BYD of China , the largest manufacturer of LiFePo4 cells , is building a huge assembly plant in Lancaster, California to build city transit busses for the American Transit Industry. These buses are to be powered by LiFePo4 cells.

This is going to change the whole picture as to pricing/availability of these cells. Last I have heard , full production in 2015.   (Assembled busses, not batteries)

Real game changer,

td

that's great news if the price is going to really drop significantly. Hope we can get hold of a few too.I have sourced lithium batteries such as sinopoly and calb directly from china prices are really good ,shipping is really unfriendly. Don't know why but its really high to any part of the world

I still don't get it.

24v/380ah in AGM L-16 form costs me something like $2K in big round numbers

24V/400ah in LiFePo4 would set me back about $3.6K in big round numbers, and last 4 to 5x as long, and not be a toxic mess.
(and have 5x the warranty).

So, Why is it that lithium is still considered too expensive?

I'm confused.

Just bought 24 volt 380a.h. Flooded lead acid $840 delivered  good quality industrial set.
Best quote LiFePo4 200 a.h. 24 volt set, $3000 with BMS.  Price getting better but were not there yet.
400 a.h. Complete about $6995. F.O.B. Fremont ,Calif.  BYD cells , assembled in CA.

another two years they will be more reasonable as BYD ramps up for the demand.

td

well they are considered expensive because it is difficult to fork out that kind of cash for a set,but that s just my opinion

I'm in the same boat there, I like the idea of lithium but the cash is not there right now. I think that they will be a better solution as you get rid of the toxics, explosive gasses, etc. What intrigues me most is the long life. I get real good life from FLA but that is where my experience is. I did a winter in Fairbanks Alasks working for Alaskan Husky Battery Company building batteries that work at 70 degrees below so I have lots of experience with FLA and regularly get 10-12 years from a well maintained set. I just bought a set of Rolls S-530 RE L-16's headed to the scrapyard for $20.00 from a person who did not know how to maintain them.  Two weeks on a solar trickle charge with high voltage panels direct connected ( no cc only a reverse flow blocking diode ) they are coming back nicely....all cells within .012, and I find that to be typical.  I think that a good 50% of batteries of all types die from "LOM"  ( lack of maintaince )  now if installers could educate buyers about maintaince!
I think that most consumers believe that unlimited power will come out of an outlet regardless of circumstances.

Maybe if I win the lotto I will buy LiFePo4 batteries and a new EGO inverter and maybe another Classic or two.....LOL!

So what is your secret to getting good life out of FLA?

Jimbo,

Glass float hydrometer!  Better ones count! Must be able to resolve .005 s.g.
Chart the result....I have a notebook that I log my weekly hydrometer readings for each set

Don't run them down too much! And don't use only the top few % of capacity
Chargers must have proper profile or your eye on it in case of old school bulk charger
Heat kills batteries, keep them cool, use chargers that have thermal feedback. (BTS) inverters/chargers should have BTS as well
Good source of distilled water, it's not all the same!  Minerals will kill a battery quickly!

Biggest mistakes I see, too low a voltage for job ,too high current, too big of inverter for job

It's all about maintaince. I am very mechanical so it's just my nature.


If I have a set in trouble I correct the problem before it gets worse, if I am getting low readings on one cell maybe down .020 from the others I pull that set from service and charge with a high resistance source. Right now I'm using some Cadmium Telluride panels at 92 v.o.c. directly connected through diode to 24 volt set. This provides high enough voltage to burn sulfation from cells but will throttle current to a safe value. I am just looking to wake them up, not a hard charge, sometimes I will let them sit at a charge only a few percent of the 20 hour rate for several weeks.

There are many little things that add up and count.

td

Thanks for the advice.

QuoteDon't run them down too much! And don't use only the top few % of capacity

Any figures you like to use?

Jimbo,

I use mostly L-16's and don't charge set until at least down 20-25% more like 45-50% unless I'm in summer foggy season and almost never go below 70 % total A.H. capacity.  I have two separate banks for my household (32 foot Tioga Motorhome and tiny cabin) and two more for my 40 foot shipping container workshop and use one set or the other switched with 300 amp marine switches so I'm using "A" bank and charging "B" bank...way better control.....but then I have been tinkering electricity since the early 60's....am commercial electrician for a living....AC and DC...."A" bank are bought new and "B" bank are all recycled from my work

Note:  this will confuse the Classic using WBjr. it's seeing discharge from one set and charge on other set.  I use separate BTM on each set and switch them to set being

Too complicated!

td

Oh ok, my 1600 amp, 24v Raylites get a much easier time then that. The previous owners had the generator kicking in automatically at around 80% SOC but i have since dropped that down to 65-70 % SOC.  I try to test the SG every 60 days and so far they are all very close. Hopefully i will get a few more years out of them (currently 6.5 years old)

Jimbo,

IMHO, you are not exercising them enough, if you only use the top 20 % they will not get a good deep charge that will stir up all the electrolyte. Stratification will result and the acid in the bottom of the cells will be stronger than that in the top of cells....eventually sulfation will result......this is especially true for tall battery types.  I feel it is better to use 60-70 % of ampacity before recharging then recharge at 20 % of the 20 hour a.h. rate of the battery. If you only use a small percent of a battery's capacity it will eventually lose amp hour capacity. Get the manufacturers charging schedule for your battery type.


td

When i was living there it was easier to give them a deeper discharge but now that it is rented i rely on my SMA inverter to start the gen at lower SOC.

Do you equalize only when necessary or at a given interval? Raylite recommend a 2 hr equalize every 20 days. 

Living there makes a big difference, you are not doing too bad with even s.g. readings After 6.5 years.  it all depends on the loads and how you use your system. I am very frugal with electricity , it's part of my lifestyle. Born on a homestead in rural Alaska ,  never saw grid electricity till I was a teen.
You will take better care of your system than any renter will with few exceptions.

I equalize all my new batts every two weeks, on the recycle ones I eq them more until I get s.g. variation down to < .020 between cells sometimes using high frequency desulfators and other techniques , mind you I am picking up batteries that are on the way to recycle and getting years out of them , certainly not something that most people do but I do work on traction vehicles and swap out a lot of batteries for reliability issues.

The ray lite recommendation sounds reasonable, I have never heard of that company though.

td

Quote from: tecnodave on June 20, 2014, 11:06:30 PM
IMHO, you are not exercising them enough, if you only use the top 20 % they will not get a good deep charge that will stir up all the electrolyte. Stratification will result and the acid in the bottom of the cells will be stronger than that in the top of cells....eventually sulfation will result......this is especially true for tall battery types.  I feel it is better to use 60-70 % of ampacity before recharging then recharge at 20 % of the 20 hour a.h. rate of the battery. If you only use a small percent of a battery's capacity it will eventually lose amp hour capacity.

I totally agree that repeated shallow discharges are not good for the battery, but I'm not sure that stratification is always the reason.  I think it depends on your charging protocol. 

If your charge protocol causes the battery to spend enough time gassing, there will be no stratification... no matter what the SOC was when you began charging. 

Some charging protocols use the amount of time in bulk to determine the amount of time in absorb... if the battery starts out at a high SOC the bulk will be short and the absorb may be too short to stir the electrolyte.

If you use end amps to terminate absorb, you may also develop stratification if the charging current is too low.  Charging current often starts out low as the sun rises in the morning... if you start at a high SOC you may get to absorb without ever achieving a high enough current to properly charge the battery.

Let your hydrometer be your guide... it will tell you whether you have stratification or sulfation.  Technodave is quite correct that repeated shallow discharges (even if you manage to avoid stratification) are not good for the battery.

--vtMaps

vtMaps,

I agree totally, I do have WBjr,s on my Classic 150 and kid as well as TriMetrics on each system but I always go back to the hydrometer no matter what anything else is telling me.  I scored a two bulb hydrometer/thermometer.   WWII Navy Radiomans "B" battery tester that has two separate floats, one for s.g. And one for electrolyte temperature.  Very accurate and in good shape as it is 70 plus years old, wood box and all.

When I learn how to reduce iPad pixel count I will post a pic as this unit belongs in "what is it" or maybe in TJ's OP Antique collection.

td

Quote from: cpm on January 14, 2013, 04:20:12 PM
wait wait wait,

LiFePO4 cost competitive with lead acid?

Where?

Do tell, please!

I've got some medium scale liFePO4 stuff on my bike, and it's really agreeable.
but i never ever considered it for PV solar use, way too spendy.

4500 mAh - Proprietary Battery Size - Lithium Iron Phosphate (LiFePO4) - 6.4 V DC   $61.00 at Overstock.com


http://www.overstock.com/Electronics/WorldCharge-Lithium-Iron-Phosphate-LiFePO4-UPS-Battery/8726293/product.html?cid=225772&fp=f&mr:referralID=0127267a-fd60-11e3-8bdb-001b2166c2c0

Quote from: Alaska Man on June 26, 2014, 02:32:41 PM
4500 mAh - Proprietary Battery Size - Lithium Iron Phosphate (LiFePO4) - 6.4 V DC   $61.00 at Overstock.com

If you think 4.5 ah of LiFePO4 for $61 is a competitive with LA, I can hardly imagine what you are paying for your LA.

--vtMaps

Everything costs twice as much in Alaska. I dropped $2,500 for 8 AGM 6v 220ah batteries I use. That's getting real close to making the (4) Li 3.2v I'm seeing on the net equal in pricing. With this plant being open in 2015 I think it would beat the LA bank.

Quote from: Alaska Man on June 26, 2014, 04:00:21 PM
Everything costs twice as much in Alaska. I dropped $2,500 for 8 AGM 6v 220ah batteries I use.

8 X  6 volt X 220 ah =  10,560 watthour for $2500...  That's about 25 cents per watthour for AGM

6.4 volts  X  4.5 ah =  28.8 watthour for $61... That's over $2 per watthour for LiFePO4

--vtMaps

Quote from: vtmaps on June 26, 2014, 04:44:32 PM

Quote from: Alaska Man on June 26, 2014, 04:00:21 PM
Everything costs twice as much in Alaska. I dropped $2,500 for 8 AGM 6v 220ah batteries I use.

8 X  6 volt X 220 ah =  10,560 watthour for $2500...  That's about 25 cents per watthour for AGM

6.4 volts  X  4.5 ah =  28.8 watthour for $61... That's over $2 per watthour for LiFePO4

--vtMaps

Lets look at it another way shall we? In real practical application....
I've been buying 500AH/2V AGM second-hand for $110/cell. That makes $2640 for a 500AH bank. But in reality, I tried to never discharge them more than 20%, so 4800 watt-hours of usable power = 55c/Wh SECOND HAND.
Increase that to $600 ea or $3/Wh usable for new cells.

(I had three, then two, then finally only one) bank in order to get a comfortable 200AH drawdown.

I replaced those with a bank of 300AH LiFePO4 cells. They're rated for >2000 cycles @ 85% discharge. 200AH discharge is only 66% DoD, so should see significantly better life.
They cost $1.10/AH, and I need 16 cells. So 200AH*48V = 9600 watt-hours usable for $5280 = $0.55/WH usable NEW.

So even paying top dollar for brand new LiFePO4 cells, I get twice the usable capacity for the same price per WH in a smaller, lighter package.

Thanks Ross,

I rarely see people discussing/examining what is actually being used in battery banks. The need to double your bank size due to Pb restrictions changes the dynamics to make Lithium an option. As you can use much smaller banks. With batteries, it really does come down to long term usable aH. :)

Quote from: Alaska Man on June 26, 2014, 02:32:41 PM

Quote from: cpm on January 14, 2013, 04:20:12 PM
wait wait wait,

LiFePO4 cost competitive with lead acid?

Where?

Do tell, please!

I've got some medium scale liFePO4 stuff on my bike, and it's really agreeable.
but i never ever considered it for PV solar use, way too spendy.

4500 mAh - Proprietary Battery Size - Lithium Iron Phosphate (LiFePO4) - 6.4 V DC   $61.00 at Overstock.com


http://www.overstock.com/Electronics/WorldCharge-Lithium-Iron-Phosphate-LiFePO4-UPS-Battery/8726293/product.html?cid=225772&fp=f&mr:referralID=0127267a-fd60-11e3-8bdb-001b2166c2c0

Fwiw, that's not a very good price all in all, unless it's a drop in replacement for some system where the oem is much more $$$.

the  traction battery on my e-assisted cargo bike is the equiv of 12 of these, which would cost $732, but I get my 9.5ah/36v from Li Ping for $318

For me it is all about energy storage and life cycles. 

When I first decided to take the plunge I thought (8)-220AH 6V batteries would last me for days.

Well at 1760AH it would have. I had no idea about only being able to use 50% (880Ah) and then if I didn't want to drop 3 grand every two and half years, I really only have 440ah of useable storage.

So any LI/LA characteristic or any new Dodad that increases any of this is where I go next.

We can already produce relatively cheap and clean energy, the future of Solar is in storing it. IMHO

Hy all,
I'm about to buy the last piece for my PV system, the batteries... I read the discussions about LFP on this forum and I have noticed that you prefer the new gray Calbs instead of other brands, also on the other forums I have read that the Winston lifeYpo4 will have more cycle life by using yttrium in their chemistry...
For my system I don't need big discharge currents where Calbs have better results, the only parameter that I consider is the life of the cells...
What you think about this ?

Unfortunately i just dont think theres enough history to show any clear winner. Much of it will depend on freight and  finding a dealer you are happy with. These guys seem to have reasonable prices and frieght for mainland US.

http://www.balqon.com/store-2/#!/200-Ahr-Battery-Lithium-Iron-Phosphate-6-Week-Lead-Time/p/11906020/category=2736691

I'm from Europe, and here by far the best price and availability have this guys: http://www.ev-power.eu . The problem is that they have both manufacturers at about the same price for the cells and is difficult to choose... I think i will go with Winstons, for start: 16 x 100 Ah battery bank...
Now the BMS, any recomandations ?
I found this: http://www.ev-power.eu/BMS123-System/BMS123-BMS-Main-Controller.html ,the complete system is about 1000 $
Is enough to program the charger and the inverter's limits or I need to search for a BMS that have the output relays to connect or disconnect them, like this model: http://www.ev-power.eu/BMS123-System/BMS123-OFFGRID-BMS-Main-Controller.html

Quote from: lestef on October 29, 2014, 04:46:49 PM
I'm from Europe, and here by far the best price and availability have this guys: http://www.ev-power.eu . The problem is that they have both manufacturers at about the same price for the cells and is difficult to choose... I think i will go with Winstons, for start: 16 x 100 Ah battery bank...
Now the BMS, any recomandations ?
I found this: http://www.ev-power.eu/BMS123-System/BMS123-BMS-Main-Controller.html ,the complete system is about 1000 $
Is enough to program the charger and the inverter's limits or I need to search for a BMS that have the output relays to connect or disconnect them, like this model: http://www.ev-power.eu/BMS123-System/BMS123-OFFGRID-BMS-Main-Controller.html

I know very little knowledge of lithium batteries, but I would suggest you head over to the NAWS forum and search for member "pnjunction'.  He has written a lot about LiFePO4 batteries in RE systems.  One of the things I learn from his posts is that a RE system is very different from an EV system in terms of the need for a BMS.  In a RE system you are not handling the extreme high currents that occur in a EV battery.  Also, if you get balanced, large prismatic cells, and stay within the "knees" of the charge curve, you do not need a BMS.

--vtMaps

think he is right, you would probably only need a cell protection circuit . just in case .

Quote from: offgridQLD on January 01, 2013, 12:54:07 AM
Given lithium battery's are now a viable cost effective option. Also now a practical option due to large cells format with equivalent capacity to the led acid cells on offer.

Are there any future plans for the classic range to offer a charge profile for lithium battery's?

I have had a very possessive experience for many years using lithium battery's to power my electric bikes, camper van and many other devices that were previously led acid. When my led acid battery's that power my off grid home are dead there is no question about them being replaced with lithium.

As it stands now before using my classic to charge by house battery's. I  experimented with it for a few days charging a small 40ah 12v lithium pack with a small 120w PV and its possible to tweak the led acid profiles to work with the lithium though a dedicated lithium profile would be much better.

Kurt.

Hi,
Before reading this post i was really not aware to all this. you really give us a brilliant information... great post

Link removed as it resembled advertising

Here is some not so good news about a 'memory effect' in LiFePo4 batteries, especially in partial state of charge situations.

from 2013...

http://phys.org/news/2013-04-memory-effect-lithium-ion-batteries.html

Add: Bold text

Quote from: boB on January 14, 2013, 05:27:23 PM


The Classic does not need a separate LiFePo charging profile.   Batteries with the BMS (which is necessary anyway) mean that it already works for these.  You will have to change the Absorb time or maybe use the Aux 2 input force to stop charging function from certain BMS's.

boB

Is it possible to use the HVD trigger from a BMS to force the Midnite Classic into Float (ie at a lower voltage) rather than stop charging? IMO that would be a better option.

North of 56, what is it you want to do/achieve from Float charging?

It is important to achieve the  float stage but not so much the charge that happens after getting to float, over a long time period, and not much is gained from what I have read in an RE setup... very similar to FLA Float stage ie 95 to 100%

Quote from: Westbranch on February 10, 2015, 07:03:58 PM
North of 56, what is it you want to do/achieve from Float charging?

It is important to achieve the  float stage but not so much the charge that happens after getting to float, over a long time period, and not much is gained from what I have read in an RE setup... very similar to FLA Float stage ie 95 to 100%

I did mention to drop down to a float charge, and one that is similar to the resting voltage of the pack. That way, if your LFP batteries are charged up to your desired level, say 85 or 90% state of charge, you won't discharge the battery pack with any further loads (they will instead come from the excess power from your solar, etc..)

The current option is to have the BMS signal (using the HVD if triggered) will shut down the charging function. This will likely have the charging function alternating between off and on as the HVD gets triggered every time the charging function brings up the voltage of the cell. This would have it hovering around the HVD trigger point. I have read that once an LiFePo4 cell is charged, it's best to drop down the voltage to a "float voltage", which will help prevent cell degradation over time.

Another option using the HVD signal and AUX2 line, would be to latch it off, until it's reset again, but that could mean that your battery pack may be discharged significantly, it there isn't someone around at the time.

I realize that an HVD trigger event should be rare if you design your system with safeguards in place, but it could still happen. Particularly if cells are or become out of balance, in combination with various charging currents as well.

I think I follow your idea,

Quoteyou won't discharge the battery pack with any further loads (they will instead come from the excess power from your solar, etc..)

That will work for light loads ie radio, internet etc... I call it 'The Dance of Opportunity Power', just enough , not too little, not too much...

But what happens when your PV can NOT support the load, eg a fridge startup?  the battery has to/will supply the demand not met by the PV, especially the amps needed, putting your Classic back into Absorb or maybe even Bulk.. No?
As I see it, Setting the Float V (too) Low will cause you to draw more power out of the battery and thus cause unintended results...

Quote from: Westbranch on February 10, 2015, 07:44:10 PM
I think I follow your idea,

Quoteyou won't discharge the battery pack with any further loads (they will instead come from the excess power from your solar, etc..)

That will work for light loads ie radio, internet etc... I call it 'The Dance of Opportunity Power', just enough , not too little, not too much...

But what happens when your PV can NOT support the load, eg a fridge startup?  the battery has to/will supply the demand not met by the PV, especially the amps needed, putting your Classic back into Absorb or maybe even Bulk.. No?
As I see it, Setting the Float V (too) Low will cause you to draw more power out of the battery and thus cause unintended results...

With LiFeP04 batteries, the voltage after charging will drop down to a resting voltage, and that is what I was referring to. You won't see much voltage sag with LFP, plus you can set the rebulk voltage  point with the Classic.

Actually, what I was getting at was a proper way to handle a HVD from an LiFePo4 battery bms. Turning off the charging function of the Classic, IMO, is not the best way to handle this. Would it not work better if one could force the Classic into float? Is that possible?

I see what you are want to do but I don't think I would call it, ''forcing'' , it only does what you tell it to at any given time or parameter met... eg a min Absorb of 5 minutes and a max of 1 hour or an End Amps setting. It's sort of like,  "Float" is a state of mind...

QuoteWould it not work better if one could force the Classic into float? Is that possible?

So, if you have a WBjr and set the end amps appropriately,  not sure of what number you would need/use for LiFe, wouldn't that achieve what you want? 
Reason I ask  this is that the discharge curve here looks quite flat. See page 5, http://www.balqon.com/wp-content/uploads/2013/07/35_35balqon_battery_2013.pdf and the table above it indicates the max charging rate , like <3C for cells up to 1000Ah so do you say 2C to stop??

Quote from: Westbranch on February 10, 2015, 08:47:31 PM
I see what you are want to do but I don't think I would call it, ''forcing'' , it only does what you tell it to at any given time or parameter met... eg a min Absorb of 5 minutes and a max of 1 hour or an End Amps setting. It's sort of like,  "Float" is a state of mind...

QuoteWould it not work better if one could force the Classic into float? Is that possible?

So, if you have a WBjr and set the end amps appropriately,  not sure of what number you would need/use for LiFe, wouldn't that achieve what you want? 
Reason I ask  this is that the discharge curve here looks quite flat. See page 5, http://www.balqon.com/wp-content/uploads/2013/07/35_35balqon_battery_2013.pdf and the table above it indicates the max charging rate , like <3C for cells up to 1000Ah so do you say 2C to stop??

This has more to do with protecting from a cell imbalance where one (or more) cells are about to be overcharged. The BMS is there to signal an alarm of a HVD in order to shut down the charging source, when that cell(s) voltage climbs above a preset level.

If you use the AUX2 input to shut off the charging source, that would work temporarily, but as soon as the cell's voltage drops down again, the HVD signal will disappear (unless latched on) and the charging will resume, bringing the cell back to HVD again. This could continue, keeping the cell at the threshold of HVD for quite some time?

Alternatively, one could latch on the HVD signal, but then you would lose the charging from solar, and thus the battery pack will begin to be depleted, until the HVD is manually reset. You could have it automatically reset at a preset lower voltage. The best solution though, would be to "force", ie signal, the Classic into float mode. In float mode, the charge controller will keep the battery pack at it's lower resting voltage, and the charger will still work to supply solar power to any loads that come on. Is it clearer now?

Not at all.... I must be heavy headed today... here are some specs from a Balqon 18KwH battery
http://www.balqon.com/online-store/#!/Lithium-Battery-Storage-18-kwhr-1-week-Lead-Time/p/34642671/category=2860254

Charge Voltage: 28.0 Vdc Bulk Charge | 28.8 Vdc Absorption Charge | 26.5 Vdc Float Charge
Discharge Voltage: 24 Vdc Max

which uses 8 cells @  700Ah cell  @ 3.25V/cell
= / cell

Charge Voltage: 3.5 Vdc Bulk Charge | 3.6 Vdc Absorption Charge | 3.3125 Vdc Float Charge. Discharge Voltage: 3 Vdc Max

So using these real life numbers, what values would you expect to use in a charge regime?

Quote from: Westbranch on February 10, 2015, 11:59:46 PM
Not at all.... I must be heavy headed today... here are some specs from a Balqon 18KwH battery
http://www.balqon.com/online-store/#!/Lithium-Battery-Storage-18-kwhr-1-week-Lead-Time/p/34642671/category=2860254

Charge Voltage: 28.0 Vdc Bulk Charge | 28.8 Vdc Absorption Charge | 26.5 Vdc Float Charge
Discharge Voltage: 24 Vdc Max

which uses 8 cells @  700Ah cell  @ 3.25V/cell
= / cell

Charge Voltage: 3.5 Vdc Bulk Charge | 3.6 Vdc Absorption Charge | 3.3125 Vdc Float Charge. Discharge Voltage: 3 Vdc Max

So using these real life numbers, what values would you expect to use in a charge regime?

A voltage that corresponds roughly to a 90% or slightly more state of charge is one I would use to trigger a HVD, to prevent overcharging a cell. I would not use the BMS that you referenced, as they  would likely bring the state of charge up closer to 100%, which will impact the lifespan of the battery pack. I think that the trigger voltage for HVD will vary somewhat, depending on the rate of charge at the time. Ideally, you would want the pack go to float before an HVD is triggered. Again that voltage may be dependent on the rate of charge, and a charging regime specific to the type of LiFePo4 cell would be ideal.

Quote from: Westbranch on February 10, 2015, 11:59:46 PM
So using these real life numbers, what values would you expect to use in a charge regime?

Westbranch, you may want to check out this link if interested in charging voltages. A member there (karrak in post #9) has posted voltages he uses to manage his Winston cells. Looks like he occasionally goes to 3.45 volts per cell, which he figures corresponds to about a 95% state of charge, and then drops down to float at about 3.32 volts per cell. He rebulks at about 3.27 volts.

http://forum.solar-electric.com/forum/solar-electric-power-wind-power-balance-of-system/off-grid-solar-battery-systems/20447-charge-float-and-cutoff-voltages-for-large-lifepo4-cells?21701-Charge-Float-and-Cutoff-Voltages-for-Large-LiFePO4-Cells=

Hi North of 56, I guess I am back to ''why can't you just set the CC to your safe values'' and let 'er rip with a WhizBang to control the cutoff with float at 3.32V?

As in Karraks example numbers, Charge at 3.45V (or less) and go to Float (3.32V) when Amps into the battery drop below C/20 (5%)

Quote from: Westbranch on February 12, 2015, 04:13:34 PM
Hi North of 56, I guess I am back to ''why can't you just set the CC to your safe values'' and let 'er rip with a WhizBang to control the cutoff with float at 3.32V?

As in Karraks example numbers, Charge at 3.45V (or less) and go to Float (3.32V) when Amps into the battery drop below C/20 (5%)

I guess one could do that, but the BMS is there for a reason, to protect your valuable investment. And the LiFePo4 cells can go out of balance, as you are dealing with gradual cell degradation over time.

The way I see it is, you want to charge the cells to about 90% state of charge on a regular basis, to maximize usage of the storage capacity of the bank. At that charge state, you are right in the neighborhood of cell degradation. If you rely on just pack voltage an even slight cell imbalance could put one or more cells into that 90 to 100% range, even though pack voltage may indicate otherwise. That's where the BMS comes into play. As soon as one cell goes above the 90% level, the charging is triggered to go to a lower float voltage.

The imbalance will grow worse over time if you just base the charging on the pack voltage, and a lower capacity cell, is continually reaching a higher state of charge. THe degradation will be most pronounced with that cell, and it's capacity reduced more than the higher capacity cells over time. That's also why I think it's a good reason to top balance (as opposed to bottom balancing). All the cells will reach the same state of charge and cell degradation will be more or less equal over time. Cell degradation is more prevalent at a higher state of charge, than at a lower one. Of course, you don't want to go too low either. Does that make sense?

Yes and to make sure you don't go over the top so to speak, I agree that a BMS is essential otherwise you end up like WRT with a .... dead , verrrry dead LiFePo4...

battery.http://midniteforum.com/index.php?topic=2270.0

so you use the CC to keep your Volts low and the BMS is the safety valve just in case ...

Quote from: Westbranch on February 12, 2015, 07:28:32 PM
Yes and to make sure you don't go over the top so to speak, I agree that a BMS is essential otherwise you end up like WRT with a .... dead , verrrry dead LiFePo4...

battery.http://midniteforum.com/index.php?topic=2270.0

so you use the CC to keep your Volts low and the BMS is the safety valve just in case ...

Thanks for the link Westbranch. That was an interesting read and unfortunate for the OP to lose his battery pack. Looks like having an extra back up just in case, would not be a bad idea!

About keeping the volts low with CC, I still think that you want to maximize storage, and get up to about a 90% state of charge. The issue I see is that 90 to 100 % state is an area you want to avoid, and reaching that with one or more cells may be a more frequent event than one would hope for. The other question I have is how well can you judge the charge state of each cell, with varying charge currents? I'm thinking that a higher charge current will skew the voltage higher, whereas a very low charge current will allow the charge state to climb higher, perhaps than interpreted?

I just picked up on a missed fact.  see the graph on discharge mentioned above.  Note the NOMINAL VOLTAGE!   = 3.25V
Now think about a FLA battery, its Nominal V is 12 yet we know it is able to take 13.2V to get to 100% charge..  This makes me think there is a lot of head room for topping off a Life battery.  Note the

3.5 Vdc Bulk Charge | 3.6 Vdc Absorption Charge | 3.3125 Vdc Float Charge
28.0 Vdc Bulk Charge | 28.8 Vdc Absorption Charge | 26.5 Vdc Float Charge

very much like my AGMs...

So a question then. Do you think it's possible to fairly accurately predict the charge state of an LiFePo4 cell (or pack) by the voltage, when your charge source is not constant?

I know that with FLA batteries, you may have an idea of the charge state when charging, but you would also look at the amount of current going in at the time. Even then you wouldn't be certain? The voltage can be skewed up or down considerably, depending on the solar production. I know that LiFepo4 voltage outputs fluctuate to a lesser degree than FLA, but there is still quite a range from resting (ie 0 amps in) to bulk, the posted charge rate.

I'm thinking that getting a bank to a 90% charge state may not be so cut and dried, as you're dealing with varying charge currents with solar power? The voltages you referenced are based on a constant charge rate.

I haven't had any issues with my LiFePo4 (Calb CA) battery bank without BMS management. It has functioned the same since day one of having its bottom balance amongst the 16 cells I have in series. (48v setup)

Frankly. I do not see the need for them. The cells all stay balanced within 15mv of each other. This is using 2 years of Off-Grid, full time household usage of them.

// MODIFIED to reflect 15mv //

Being new to solar and battery systems, I sure appreciate this forum as a source of information and debate as we designed our grid-tie hybrid system.
inMichigan

Hello everyone!

Due to LIFEPO4 chemistry having two different stark contrasting camps regarding as best setups I wanted to add my two cents. It has been slightly over two years now since I installed a battery bank consisting of 16 - 100aH CALB CA series cells. A theoretical bank of just over 5 KWH. The paperwork has it listed that if you only routinely use 80%DOD you are supposed to get a 2000+ cycle-life. 

In my setup, I purchased a couple acres in Colorado in the beautiful Rocky Mountains and have been powering a Travel Trailer/Tiny House. I have 2000 watts worth of Solar coming in and a 200v Midnite Solar C.C to regulate it all. I do not have the Whizbang JR. However, I plan on getting it.

When I first got the cells I opted to bottom balance them. The idea was that even though you purchase a set of 100aH cells from the same batch, it does not mean they all are exactly 100aH. They very well could be broken down as such: 100, 102, 105, 97 etc. I have heard it described as having a bunch of sticks to varying lengths. (Placing one end of them against a surface so you can see the "jagged" variance at the top)

We all know for longevity with any battery chemistry that you get the most cycles from not fully utilizing the battery capacity. IMHO I went with the idea that through bottom balancing I would be able to charge all the cells up to a point where they are all at, say, 90aH with no variance. Removing the runaway at the top. I felt that in a real world situation it is more likely that a bank will be accidentally over-discharged rather than over-charged. Through cells that match you would have very little chance the stronger cells would kill the weaker cells in that condition.

Two years ago I pulled all the cells down to 2.700v and managed to get all the cells balanced within 5mv at that level. I have the CC set to charge them back up to 3.5vpc.

NO Equalize. Absorb = 3hr BULK=3.5vpc FLOAT= 3.34vpc REBULK=2.8vpc ENDAMPS=8

Using a multimeter on each cell when in Absorb mode (And nearing the END AMPS) after two years of daily cycle-real world usage I see them still within 15mv of each other at their upper charge states (where they would start to deviate from each other).

I think so far that is fantastic to see!

As far as ideas concerning whether you should use FLOAT for LIFE cells, I have not had any problems with it. For myself I chose a voltage that closely matches their resting voltage. Something that over the last two years has shown to not slowly increase their voltages when I am not around to monitor. The cells would always have a small load on them to take off a bit of charge. The CC and Inverter.

What about ENDAMPS? According to spec sheets 0.05C is supposed to be where you consider the cell full. In my case of 100aH cells that would be 5 amps. However, because I do not have a Whizbang Jr, I find that if I use 5amps the voltages on the batteries shoot up further than I like. This is because there is always a couple amps worth of background load in the morning before it is fully charged. As the CC cannot tell that by itself it ends up putting in more aH to the bank than I want. To fix that I just up the ENDAMPS and the voltages stay where I want them.

- Cloud

Cloud , How is it you DON't Have a WB-jr , but all that $ in storage . You can have one , but leave it unhooked & / or set it off .
You do need the shunt also ..
Im not getting this thinking . I think there 50pluks and really programmable , but them new style potatoes with nails are WAY more Pluks !?
VT

Haha @ CDN-VT :

I can easily see your point! I have $2500 USD in 5 kwh worth of storage, but no $80 USD WB-JR? The WB came out after I got everything setup. Everything has been running smoothly that I guess I sort of figured out about where I should take the pack down to voltage wise. I typically only use 2 KWH a day unless I make a point to use a space heater. 

I WILL get one shortly though as the idea of knowing a much more precise number of watts going in and out makes for being able to fully utilize what I purchased. The other main idea about having one is to be able to set the ENDAMPs to 5 rather than 8.

I'll get right on that!  ;D

I see the new Morningstar controller is advertising it charges lithium batteries but I could not find one mention of anything lithium in the owners manual. It does no more than the Midnite controllers do and seems to be just their version of the Kid .
http://www.morningstarcorp.com/products/prostar-mppt/

Larry

From reading the email I got it looks like it is a KID minus ~5 amps, ....didn't dig too far...

What features do you think would have to be added to the Classic to make it the perfect lithium battery charger ? 
I know for my LiFePo4 ebike battery the critical features are that it go to top voltage but at that point it needs to be able to turn on and off in order for the BMS to do it's thing for balancing. So I guess that means it goes from constant current to constant voltage at certain point.

Larry

Quote from: ClassicCrazy on October 23, 2015, 01:00:46 PM
What features do you think would have to be added to the Classic to make it the perfect lithium battery charger ? 
So I guess that means it goes from constant current to constant voltage at certain point.

That sounds like the transition point from BULK to ABSORB to me........??

Quote from: Westbranch on October 23, 2015, 01:30:32 PM

Quote from: ClassicCrazy on October 23, 2015, 01:00:46 PM
...   So I guess that means it goes from constant current to constant voltage at certain point.[/b]

That sounds like the transition point from BULK to ABSORB to me........??

BUT,  Bulk is not Constant Current,  it (to me) is;  Maximum Available Current,  until the Absorb set-point is reached,  then,  it is Constant Voltage ...  IMO.

Vic

Quote from: Vic on October 23, 2015, 01:46:26 PM

Quote from: Westbranch on October 23, 2015, 01:30:32 PM

Quote from: ClassicCrazy on October 23, 2015, 01:00:46 PM
...   So I guess that means it goes from constant current to constant voltage at certain point.[/b]

That sounds like the transition point from BULK to ABSORB to me........??

BUT,  Bulk is not Constant Current,  it (to me) is;  Maximum Available Current,  until the Absorb set-point is reached,  then,  it is Constant Voltage ...  IMO.

Vic

And if you were to limit the input or output on Classic  then the power would not be available to loads. Someone asked on another thread recently about a feature that would limit what goes to the battery only - that might do it - so if you set certain number of  amps to battery then it could never exceed that but full array potential could be available for loads.

Larry

I purchased the Midnite Solar 200v Classic specifically because I went the Lithium route. Really any controller that allows you to specifically change the voltage set points will be able to work with lithiums.

Lithiums (LiFePo4 in my case) will readily take the amps. I have my charge controller setup to BULK everything into it until it reaches 3.5v per cell (I have 16 cells so once it hits 55v it switches to ABSORD mode) Absorb mode holds it at a constant voltage of 3.5v per cell/ 55v until the current drops to 0.05C or 5amps in my case (100aH cells) which triggers it to go into FLOAT. I have my Float set to maintain them at 3.34v per cell.

Note: Due to not having a WHizbang JR to more accurately have the CC switch from Absorb to Float when it reaches 0.05C due to possibly high background loads I simply program the CC to use 7amps as the ENDING AMPS.

My Off-grid system has been working out perfectly for 2.5 years this way. The cells still remain within 15mV of each other.

Thanks for the info on how you setup your Classic for your lifepo4 batteries .

No problem, Larry.  8)

With your 100 AH pack - how many AH will you take out before you hit the voltage cutout that you don't want to go below ? No problems running your inverter ?

Larry

Without a Whizbang JR for more precise readings of aH in/out I simply guestimate. Rarely do I have the bank fall to 52v before i got to bed and wake up to the sun charging it back up. With the 5120 Watt-hours nominal in the bank, I make a point to use no more than 4 kwH average or 80% for cycle life longevity.

The inverter hasn't any problems. It is an Outback VFX3648. It cuts out 48v. I've only had it shut the system down once in the very beginning. 48v = 3v cells = 100% DOD. Not something you want to do a lot, but they recharged without incident.

I need to purchase or borrow an outback mate in order to change the voltage set points. I would move them to reflect a 90%DOD for system shutdown as that would be a rare occurence but still give you a safe margin. Side note: Also need to find a mate in order to change the charging set points to work with a lithium profile should I ever decide to purchase a backup generator. In the 2.5 years I have managed to not need one. :)

You have me looking at the Calb 100 AH batteries now. I have been thinking of lithium. For now my battery location would get cold in the winter so not sure if that would be too good a thing for lithium or if they need to have temperature compensation setpoints like lead acid do.  Probably better to keep all the cells in series - though I have 24v system and inverter now.
I have an electric bicycle with 48v 10 AH lifepo4 battery on it that has been working great for more than 5 years even though it has been abused in many ways. I have always just relied on the battery charger and bms that came with it to keep it happy. I had problems with cell balance when the charger failed and I was trying to use different charger to do a few cells at a time - bad idea but I learned a lot.  I guess I have about 10,000 miles on that battery pack now though I swapped out a few cells. It is about 60 to 70% original capacity I am guessing.
I really would like to move the solar up to lithium .

I'm happy with Lithiums and the CALB grey cells. As far as I know the Calbs do not suffer from capacity loss as much as Pb cells do in colder temps although there still is an effect. The only thing to note is that they make a point of saying you should not charge up cells if they are below freezing (As it can create internal shorts?).

I have our bank sitting indoors below the CC. They do not off-gas thus no longer need to be relegated to a cold "outdoorish" setting. Plus with The smaller form-factor it is fairly easy to hide them inside. The entire dimensions of a 5 kwh bank of 16 cells is 11"x21"x8" @ 150lbs

I found some good discussion on bottom balancing lithium batteries here - and some reasons why BMS is not needed.

https://www.solarpaneltalk.com/forum/off-grid-solar/batteries-energy-storage/18809-lithium-top-or-bottom-balance/page2

Larry

"Depending on the BMS type used, I would think you should still be able to use diversion to use that extra energy.

The thing that would change would be the diversion voltage set point.  For instance, if the BMS doesn't
care what you give it after the battery is full, divert at Absorb.

Or, maybe divert at just slightly over the battery open circuit voltage.

As soon as you start diverting at lower than the battery's resting voltage, it won't be full anymore.

boB"


After reading this thread and specifically this post i would would like to conclude that this setting is ideal for solar/wind/hydro :

"As soon as you start diverting at lower than the battery's resting voltage, it won't be full anymore.

boB"

My reason is because from reading i have come to the understanding that it is not good for lithium to be at  100% they prefer 80-95% approximately.

My question however is what is the most ideal voltage setting for a Midnite classic in relation to the specific lithium.

Am I correct?Please correct me if i am wrong.

Also i understand the once your Midnite Classic has the latest firmware the Aux 2 can be utilized to stop charging lithium which function is this please list by name.

I am also optimistic about lithium since i have a failed cell in my bank and have to think of getting a new bank.It is practically the same cost for me at my location of residence compared to lead acid technology.
Thanks in advance.

Aux 2 used with the Whizbang can control the battery to stop charging   with the End Amps setting - when End Amps is setup it will go from Absorb to Float at whatever is in End Amps .

Larry

point taken i do have a whiz bang.

is it then logical to make use of this to not achieve 100% soc

Quote from: mahendra on January 03, 2016, 06:24:46 PM
is it then logical to make use of this to not achieve 100% soc

You might actually be able to use the WB Jr. and Aux 1 SOC% function to operate
a relay or SSR or something when the SOC reaches 95% or whatever ?

boB

can you elaborate a bit more boB?

From the Classic Manual

AUX 1 - Control Settings (12V @ 200Ma or Dry 1A Contact)
SOC % Low
This mode will set AUX1 to 0.0V according to the LOW % and HIGH % settings. HOLD (LOW) and
DELAY (HIGH) activation TIMES can be set in seconds. SOC %=HIGH=0V SOC %=LOW=12V
SOC % High
This Mode will set AUX1 to +12V according to the LOW % and HIGH % settings. HOLD (LOW) and
DELAY (HIGH) activation TIMES can be set in seconds. SOC %=HIGH=12V SOC %=LOW=0.0V
If the classic is set to do an auto-restart at 23:59 (midnight), the state of the AUX1 will be remembered
so it will return to the last state (+12V or OFF) after it resets and comes alive again.

So you can hook up a relay to AUX 1 to control whatever according to what the SOC is .

I'm not sure it is inherently bad that Lithiums are at 100%SOC. Rather I feel it is more of a condition where you are dealing with the sharp jump in voltages due to the steep charge curve on the top and lower ends. Plus, not all cells will be the same capacity regardless of manufacturing dates/batches. Thus you find yourself dealing with over-charging some cells in the hopes of getting the others to 100%SOC.

LFP cells work quite well simply using the ENDAMP function. It brings them to what they consider to be fully charged without getting into dangerous sections of the charge curve.  LFP cells use 0.05C for their ENDAMPS. 100aH = 5a or 180aH = 9a (180*0.05=9)

For FLOAT (With the idea of having a full battery when the sun goes down) you need to use a voltage slightly above their resting voltage. In LFP cells that works out to 3.34v (resting). I chose to use 3.375v as it keeps them full while not being enough to slowly overcharge a cell throughout the day.

Whatever you do, stay away from EQUALIZE. No need to cook your cells.

Added: I wouldn't trust the ENDAMP function (at face value) unless you are using a WBjr. The WBjr sees exactly what goes into the bank (Already calculating for background loads) so you get an accurate ENDAMP. Without it, as I had lived for a couple years without one, you have to add a few amps to the ENDAMP number to get a rough estimate. I figure that when everything is idle in the house it still consumes 2-3a, so I setup the ENDAMPS to be 8 rather than 5. Since purchasing the WBjr it is safe to bring it back to 5.

I also like having the WBjr because it allows you to fully use your system as soon as you wake up because you do not need to compensate for heavy background loads (possibly over-charging your LFP pack) as it knows what is going in/out of the bank.

In other words.... ME = Happy camper!

Hello, sorry to kick this one off again. 
But are there any specific charge profiles to set the classic 200 for a 400ah lifepo4 battery bank?   Has anything changed in the past year in regards to how someone using lifep04 batteries has set their classic?
I nearly have my wiring all done, bar picking up my 16x100ah cells in the city next week (swapping them with 4 x 400ah cells i haven't used yet) and wiring them in. 

Thanks.

Quote from: aussiejohnny on January 11, 2017, 11:06:36 AM
Hello, sorry to kick this one off again. 
But are there any specific charge profiles to set the classic 200 for a 400ah lifepo4 battery bank?   Has anything changed in the past year in regards to how someone using lifep04 batteries has set their classic?
I nearly have my wiring all done, bar picking up my 16x100ah cells in the city next week (swapping them with 4 x 400ah cells i haven't used yet) and wiring them in. 

Thanks.

Are you planning on using bottom balancing ?
Are you going to have any kind of BMS protection ?
I would make sure you have something independent of the Classic to disconnect if voltage goes too low.

Larry

Hi Larry. 
No i top balanced my cells. 
Will not be using a BMS. 
Will be getting a control box fitted that automatically deals with lvc and hvc.

System has been running 3 days now, We are completely running off the battery bank.  Very impressed in these lifepo4!  Running my 6kw ac for 3 hours was easy for them.

Still learning the classic 200 though for fine tuning.

Thanks for your reply.

Quote from: aussiejohnny on January 11, 2017, 11:06:36 AM
picking up my 16x100ah cells in the city next week

Quote from: aussiejohnny on January 25, 2017, 07:40:14 PM
Very impressed in these lifepo4!  Running my 6kw ac for 3 hours was easy for them.

I'm obviously missing something here.
3.2V/cell * 100 AH = 320 watt-hours per cell * 16 = 5,120 watt-hours or 5.12kWh
6kW AC, even without inverter losses or cables (assuming the compressor was running!) would use 100% of your batteries capacity in 51 minutes.

For it to have run for 3 hours and have anything left in the tank, your draw has to have been under 1.7 KW average, and probably closer to 1KW? Guessing it was the fan only for 75% of the time and compressor running only about 15 minutes in the hour??

(Been running my 300AH/48V LFP bank for 3 years and also love it to bits. Will be adding 600AH to it for this winter)

on the main unit outside it states max draw for cooling is 1590 watts.  so far according to my victron bvm i have seen a max of 900 watts draw.  and since putting the ac in economy mode even less while it cycles.
it's a fujitsu system, cooling has 6kw output with 1.59kw input. 

today it's been running for 2 3/4 hours and my battery is still gaining in charge from the panels.

Most small split systems 2.5kw or so have energy coaficiany of 4 to 6 so you get 400 600% more heating or cooling  power out of them than you feed in to them.

As they get larger 5kw and up his typically drops off to more like 300 400%. Usually just because of scale phisical size of the condensor and evaporator needed to keep the same eficiancy as the smaller units wouldn't be astheticaly acceptable in a demestic setting. As in a 5kw unit isn't double the size of a 2.5kw

Part of the reason why I went for several small units than one big one.

today was a stinker and i have had the ac on since 10am. my battery has been accepting charge from the solar and gone from 64.4% at 7.30 this morning to 95.6% at 1.02pm. (i think i have the victron bvm set up right, without large load the cell voltages from the cellog8 match well with what soc % the bvm shows.

8 1/4 hours total the split system ran for today. i turned the a/c off where the sun was on a fair angle and i was down to 128 watts input but still had 92.9% charge.

getting about 5-11mv difference between the highest and lowest cell according to the celllog8. i think i have set it up right, still a bit to learn in the fine tuning of the classic 200.

I recently took in a very informative seminar in Arizona regarding the RE-LION Lithium Batteries. Has anyone had any
experience with these?  They boast a full 5 year unconditional replacement warranty.  Also pricing seems to be coming down
to a point that is within reach of the average individual.

I've included a PDF file here for your perusal...

Quote from: Solar trucker on January 28, 2017, 10:51:54 AM
I recently took in a very informative seminar in Arizona regarding the RE-LION Lithium Batteries. Has anyone had any
experience with these?  They boast a full 5 year unconditional replacement warranty.  Also pricing seems to be coming down
to a point that is within reach of the average individual.

I've included a PDF file here for your perusal...

Might be okay if they will be around to back up the warranty . But reading their warranty they have a lot of discretion to deny it . The warranty on their website did not say 5 years free replacement.   It looks like they are LiFePo4 which is a good lithium technology and looks like they have some kind of under and over voltage protection built in. Not sure what they have for a BMS to ensure cell balancing or if you have to add that on ?   You can compare to prices with Calb but those you don't have any BMS protections built in but cost less - so you can add that stuff on and compare.  Also you have to take shipping into account .  Look at Calb cells here http://www.electriccarpartscompany.com/

Quote from: ClassicCrazy on January 29, 2017, 01:11:28 AM
Look at Calb cells here http://www.*********/

Your experience may be different.
My one and only dealing with them left me completely unimpressed with their lack of professionalism, their lies and misrepresentations, and ultimately an "oops" email sent by one of their staff to another that accidently included me.

I'd go so far as to say "dishonest", and I have gone out of my way to find stuff that never touches their grubby paws.

Strong words, but I've got the email trail to back it up.

To bring it back on track... under and over voltage "protection" is a failure device I chose to do without.
My inverter and charge controllers prevent over-voltage, and a backup monitoring-only system would alert me anyway. Under-voltage isn't likely to happen, since my inverter will call for a generator run if SoC gets low, OR voltage gets low, and even if the generator didn't kick in, the inverter low-voltage cutout is above the batteries minimum safe voltage.

I do however monitor individual cell voltages, which I find far more useful anyway.

i'll be getting a lvc and hvc for my system as a last defence setup.  solar controller is set to max volts so shouldn't overcharge them anyway, but just in case.  the low voltage cut on my inverter is too low, so a lvc will be installed.
my system will be left at stage for long periods of time, so alarms and whistles wont be of use when no one is there to hear them. 
i do not use a bms and will not as i deem it not needed with my system.  i do use a junsi cellog8s for monitoring the cells.

very happy with it all so far anyways. just need to do a little finishing touches, tidy up wires to monitor board etc.

Quote from: RossW on January 29, 2017, 06:34:51 AM

Quote from: ClassicCrazy on January 29, 2017, 01:11:28 AM
Look at Calb cells here http://www.*********/

Your experience may be different.
My one and only dealing with them left me completely unimpressed with their lack of professionalism, their lies and misrepresentations, and ultimately an "oops" email sent by one of their staff to another that accidently included me.

I'd go so far as to say "dishonest", and I have gone out of my way to find stuff that never touches their grubby paws.

Strong words, but I've got the email trail to back it up.

To bring it back on track... under and over voltage "protection" is a failure device I chose to do without.
My inverter and charge controllers prevent over-voltage, and a backup monitoring-only system would alert me anyway. Under-voltage isn't likely to happen, since my inverter will call for a generator run if SoC gets low, OR voltage gets low, and even if the generator didn't kick in, the inverter low-voltage cutout is above the batteries minimum safe voltage.

I do however monitor individual cell voltages, which I find far more useful anyway.

Good to know about that experience you had Ross.  I ordered the batteries from them and they came as expected.  There are other Calb dealers - they all sell them and ship out of same place in California it seems. 

In regards to low voltage protection - yes the inverter will not run , but I had bad experience where the Classic itself ran them down below the safe point. My experience with the Calbs is that if you are doing bottom balancing like I am doing  gotta be real careful ! The voltage will take a dive and crash really fast. First mistake I made was I forgot  to derate my capacity to 80 from 100 SOC since I was bottom balancing and thought I had more in them than there was. And I think my inverter did not shut off like it was supposed to.  At the very least there should be an alarm when the voltage goes below a certain point. I think the problem with my Classic running them down when there were no other loads was because they were cold and capacity was decreased quite  bit. I didn't have the solar on since can't charge them below freezing. Lead acid is a much better choice if batteries are going to be very cold.

I just have small lithium setup so I could get the hang of them !

Larry

This is a very helpful thread, and seems to be the big-daddy of Lithium-ion battery threads here. ? So I hope it's ok to wake it up from it's slumber.

I am looking for a latching relay for my new LiFePO4 array, and not having much luck. Wondering if any of you have located a suitable latching relay for either Low Voltage Disconnect (LVD) or High Voltage Disconnect (HVD) to protect your Lithium battery array.

Specifically, I'm looking for a NORMALLY CLOSED, LATCH ON OPEN contactor. 12vdc is ideal. When energized the contacts open, disconnecting the load, and stay open even if the 12v battery powering the relay dies.

Ever run across such an animal?

Gigavac has some
http://www.gigavac.com/catalog/power-products/gx-series

Larry

@cniemand, believe it or not I have just read every one of your posts in this thread. Probably twice. Mainly because you seem to have had your LFPs for some time now, and you have posted lots of [helpful] details. Looks like it has been a year and a half since you last posted to this thread. Just wondering how your batteries are holding up. Capacity still about the same?

jim

Still subscribed.

Larry : Are you still 'derating' your pack? Curious. I have never had that issue. When i first got them, i used a much lower charge voltage and inadvertently discharged them to the point the inverter shut it all down. After re-bottom balancing them and changing the voltage set points, no more worries. I found that it isnt a huge concern if you bottom balance them closely as when nearly empty, they aren't so far off to kill one another. My issues always were that the differences in capacity.... If i tried to use everything in them by fully charging them at higher voltages, a cell or two would really shoot up before others. Calbs tend to all be over 100ah regardless of buying '100ah' cells.

Ross : 3.5 years is awesome! Good stuff.

Five/Jim : Last month marked my 4th year running a full time offgrid LFP setup. Surprisingly I havent had any issues and have gone all this time without owning a generator. My stance is still the same of voltage setpoints and bottom balancing. Through both of those, the system has remained hands off (aside occasionally taking a multimeter to the bank for verification) With that, I am not 100% certain what my battery capacity is relative to day one. One of these upcoming sunny days I need to fully discharge the bank from 100% to ~0% and then back to Float with the house inverter off to get a more accurate measurement of what went into the bank minus charging losses. From an anecdotal perspective, I do not notice any difference in capacity. That is, my regular routine doesn't bring the SOC any lower. Typically I do not use more than 50-60% DOD. My usage could be considered mild to moderate. If we are to take Calb paperwork concerning cycle life, mine would mimic closer to 5000 cycle life. My lifetime Amp-hours currently is 104,356. Take that into my 100aH bank, I am sitting at 1000 cycles. Still running well without noticeable degradation of capacity.

Cloud

My only issue with the whole system is one : About a month ago, the graphics panel on the Midnite solar 200v CC went funky on me. If i look straight on at it, it looks all black. If i look from an angle or underneath then I can read the screen as if it was normal. I purchased all my components from a dealer in Minnesota 4 years ago, but has since changed to a installer direct only company. I am not sure if I still fall under a warranty or not. I guess I can eventually purchase a new MNGP, but so far, I get by with just looking at it from a 45* angle. Still very happy with midnite solar products and the whizbang is the best invention ever. Surprised I waited a couple years to get one.

inquire via a "TICKET', on the main MidNite.com page , right under the Kid ad under the banner...  have to look for the link...

Thanks, West.   

Quote from: Cniemand on July 21, 2017, 07:19:48 PM
Still subscribed.

Larry : Are you still 'derating' your pack? Curious. I have never had that issue. When i first got them, i used a much lower charge voltage and inadvertently discharged them to the point the inverter shut it all down. After re-bottom balancing them and changing the voltage set points, no more worries. I found that it isnt a huge concern if you bottom balance them closely as when nearly empty, they aren't so far off to kill one another. My issues always were that the differences in capacity.... If i tried to use everything in them by fully charging them at higher voltages, a cell or two would really shoot up before others. Calbs tend to all be over 100ah regardless of buying '100ah' cells.


Cloud

Not sure what caused it last year but most of my cells went way below 2 v . I had shut off the PV and the inverter because it was getting too cold to charge batteries but left the Classic on  and thought that there was a 50%  of capacity left. One day I went to look at Local Status App and the system was not on - so I went out and looked and the Classic was shut off due to low voltage and the cells were too low to run it. I don't think I was able to get the inverter to charge it because it wouldn't turn on either due to low voltage.

Was wondering how I was going to get myself out of that mess cause I only had small RC chargers and it was going to be a pain to try to get all 16 cells up one at a time. Then I thought to use my ebike 6 amp 48v charger and that did the trick and stimulated the cells enough to come up in voltage enough to turn on Classic and Inverter so I could charge them.

I had them off all winter because of below freezing temps and not able to charge them but I watched them to make sure they stayed up in voltage okay. This spring I turned them back on again and just have refrigeration loads on them and everything seems to work just fine - typically they only go down 30 % of their 80 amp stated capacity . Today we had very overcast day with warm temps so not much charging and they are at 40% but holding 52.2 v . Hopefully they will make it okay till sunshine tomorrow morning ! If I am worried before bed I will switch the refrigeration over to the other system.

Anyway - I don't know why the died that one time - that is problem with lithium - the voltage takes a dive very fast and really should have some kind of low voltage protection which I still don't have yet  other than inverter low cutoff.  So that is why I set them up at 80 ah to give me some buffer and not take them too low again. I don't know if the cells got damaged when they went below 2v though I think I caught them fairly quickly .

Larry

 

If I recall correctly, an outback inverter disconnects down around 40v. For you and I with 16 cell systems, that means if the inverter is shutting down the system then each cell is at 2.5v, whereas we should consider 3.0v to be the absolute low 100%DOD.

Larry: Did you see the voltages all remain pretty close of each cell at that SOC? It no doubt does some effect to their capacity long term with bringing them down that low, but I suspect, like my own bank where I had the same occure once that they will all recover nicely.

LFP charge/discharge curves are very linear and the ends are very steep. Quite unique. At the ends it can be seen as a negative, whereas having most of the curve very linear makes for stable voltages.

I agree, Larry. Keeping away from an active BMS solution that could cause overvoltage destruction should one of the boards conk out is my philosophy, however, having a low voltage disconnect is a useful backup. I do not actively try to use the whole capacity of the cells (top end, 100ah came from Calb ~110-115) with my CC setpoints a overvoltage is not likely unless the cc fries. (If it did i suspect more likely no voltage would pass)

It has been a while since reading the Outback inverter manual. Doesn't it have a user defined disconnect voltage? If so, i would push it up to at least 48. Probably safer at 49 or even 50v.

( Somedays I think how nice it would be to have an outback mate to finally program the inverter for a LFP profile... Then i could setup a genny and have the software disconnects. BUT $3-400 bucks when i would use it once. "Set it and forget it" Meh. )

Just looked the manual over. Our VFX3648 inverters have a voltage range of 42-68vdc. They cut out far too low for LFP chemistry.
The colored LEDs for battery status are as follows :

GREEN = 50v+ (The entire useful voltages of LFP would fall here)
YELLOW = 46-49.6v (At this point you are already beyond recommended 100%DOD or 3.0v per cell)
RED = 42v (2.625v per cell. Eeks)

Having a LVD at around 50v would keep all the cell voltages above where they start to crash.

Quote from: Cniemand on July 22, 2017, 04:53:07 PM
If I recall correctly, an outback inverter disconnects down around 40v. For you and I with 16 cell systems, that means if the inverter is shutting down the system then each cell is at 2.5v, whereas we should consider 3.0v to be the absolute low 100%DOD.

Larry: Did you see the voltages all remain pretty close of each cell at that SOC? It no doubt does some effect to their capacity long term with bringing them down that low, but I suspect, like my own bank where I had the same occure once that they will all recover nicely.

( Somedays I think how nice it would be to have an outback mate to finally program the inverter for a LFP profile... Then i could setup a genny and have the software disconnects. BUT $3-400 bucks when i would use it once. "Set it and forget it" Meh. )

I borrow an Outback Mate from a friend so was able to set it up - don't remember what I put the low voltage cutoff on the inverter at.
You can get the older model Mate for around $100  if you dig around on ebay . It might be a knockoff because there was a Chinese company that copied Outback Controllers and sell them for half the price.

I havent checked voltages on my cells for awhile. Last night I was -60 amps out of them and voltage was holding steady at 52.2 v so that is good enough for me - though I would like to run them all the way down sometime when I can watch them just to see how much capacity is in them. It could be that I can get more capacity  out of them at smaller loads than large loads.

Larry

In an older pm I reread, you mention setting the lvd at 2.5v

Quote from: Cniemand on July 22, 2017, 05:48:47 PM
In an older pm I reread, you mention setting the lvd at 2.5v

I will turn it up to 48v v if I don't have it there already .

Larry

Quote from: ClassicCrazy on July 22, 2017, 12:47:50 AM
Anyway - I don't know why the died that one time - that is problem with lithium - the voltage takes a dive very fast and really should have some kind of low voltage protection which I still don't have yet  other than inverter low cutoff.  So that is why I set them up at 80 ah to give me some buffer and not take them too low again. I don't know if the cells got damaged when they went below 2v though I think I caught them fairly quickly .

Very educational. Glad they came back for you. I just iterated through a low voltage cutoff thread over at the Arizona Wind and Sun forum to come up with a solution for my rig. Lots of good ideas for LVD were flushed out. Might be of interest...

http://forum.solar-electric.com/discussion/352277/desperately-seeking-normally-closed-latching-contactor-but-not-that-desperate

Quote from: Cniemand on July 21, 2017, 07:19:48 PM
Five/Jim : Last month marked my 4th year running a full time offgrid LFP setup. Surprisingly I havent had any issues and have gone all this time without owning a generator. My stance is still the same of voltage setpoints and bottom balancing. Through both of those, the system has remained hands off (aside occasionally taking a multimeter to the bank for verification) With that, I am not 100% certain what my battery capacity is relative to day one. One of these upcoming sunny days I need to fully discharge the bank from 100% to ~0% and then back to Float with the house inverter off to get a more accurate measurement of what went into the bank minus charging losses. From an anecdotal perspective, I do not notice any difference in capacity. That is, my regular routine doesn't bring the SOC any lower. Typically I do not use more than 50-60% DOD. My usage could be considered mild to moderate. If we are to take Calb paperwork concerning cycle life, mine would mimic closer to 5000 cycle life. My lifetime Amp-hours currently is 104,356. Take that into my 100aH bank, I am sitting at 1000 cycles. Still running well without noticeable degradation of capacity.

Thanx for the update. Happy to hear your system is doing so well. So, still the same charging strategy. The main thing I noticed about your charge profile is that you are setting float close to the array's resting voltage. When I went on my hunt for the best LFP profile for the Classic I got back "set bulk=absorb=float".

When I went to program the classic there is of course no bulk setting per sey. And you must set float at least .1v below absorb. Still, I have gone with that strategy so far. And I use a whiz bang to terminate absorb (go to float) when end amps = 1. So specifically, I set absorb to 3.45 (55.2) and float to 55.1.

But your notion of dropping float down to near resting voltage is intriguing. It would be interesting to run some load tests and see how much difference in total capacity there is between the two strategies. If any? I'm assuming that my batteries are still charging to 90% or so at the top end (depending upon which charts one consults).

So, why am I setting end amps to such a low value, you ask? Using that often quoted formula of charging to 0.05C, my 144AH pack should have end amps set to 7.2. However, for now, I'm going by the battery manufacturer's spec sheet, which says to stop charging at 1A (see attached). These are also 3500 cycle rated cells, which is why at the last minute I bought them in lieu of the Calbs. Should I believe the spec sheet? Well it all depends upon whether is was assembled by the engineering department or the marketing department. Who knows?

http://www.electriccarpartscompany.com/New-Energy-72Ah-Aluminum-Encased-Battery

By the way, what setting are you using for 'battery efficiency %'? The default is 94%.

/jim

Each manufacturer is different, I guess. Using the 0.05C on LFP chemistry appears to me to give a good ENDAMP number. I use that and with 5amps it charges them without seeing voltages shoot up from one another. I would be concerned with my own system of CALB 100aH that if I used a lower number they would start to overcharge and fall drastically over balanced. Afterall, the chemistry being different than PB and bottom-balancing vs TOP. PB wanting always to be topped off. I, personally do not care what the capacity and voltages are so long as between 0%SOC and 100%SOC stay within an acceptable mv range/balance. 55v or ~3.4v per cell and 5 ENDAMPS for mr over the years seems to keep them charged up to the point of highest capacity given versus before one or two start to really break away and "over charge" versus the rest. What I am shooting for is that when the bank is nearly spent that they are as tight mv wise as I can get them so no cell has any great potential to drive another beyond recovery. Now, I rarely will discharge the bank beyond 60%DOD for longevity/max cycle life. As i see it, according to data sheets, I should attain 3000 Cycles (at constant 80%DOD usage) and between 5000 cycles (50%DOD). IDK. That is a lot of years. So far, I am at 1004 cycles 4 years in. Not bad for such a small bank (5 KwH nominal) with big screen tvs, vacuums, space heaters to burn excess, hot plates etc. With a largish Array, you are free to use gobs of juice during the days.

Over the first year or so, I found that a float voltage that is just slightly above the battery true resting voltage is perfect. It keeps you from either over voltage (so long as you are constantly bringing the battery down over night, rather than a non attended outpost) and slowly discharging it before the sun goes down, leaving you less than 100%. The "problem" with LFP is the linear voltage curve. If you set your voltage below the resting voltage, then you may end up with a battery that floated all day and left you with 80-90%SOC at night rather than 100% based on the linear voltage curve alone.

That is why my voltage setpoints are all very close eventhough each mode: bulk/absorb/float are all completely different profiles within a cc charge parameter.

To get the fastest charging possible, without overvoltaging/pushing the individual cells out of balance permanently, and holding them sligtly above a true resting voltage to maintain 100%SOC to be used once the sun sets.

I have messed around with Efficiency a bit. Once when I first got the Whizbang Jr and then a year or so later when I had a number of cycles on the battery to see if there was much degradation. Both times I come around 97%. It seems to be a decent number to get the Net aH in versus Net aH out to zero out relative to when my 0.05C Endamps switches the system over to float.

- Cloud

BULK : Really is a voltage number your Battery bank can ramp up to safely that will allow as many amps to come in until it hits that safe high voltage. With LFP you can dump in a lot of amps to fill it up fast until it hits around 80+%SOC. 55v for my 16 cell bank. You could do 56 if you wanted. I leave it the same for absorb.

ABSORB : Once you reach that 80% + point, the voltages start to creep up beyond safe limits so the charge control starts to throttle the amps in to maintain a safe voltage. At 55v ( again for my specific 16 cell battery bank) it gives it just enough voltage headroom to charge the bank fast without overvoltage. Once it throttle back to 5 amps (the endamp setpoint) the individual cells are starting to widen their voltages between each other as they get to the sharp ends of the charge curve. BUT. At that point the endamp setting causes it to go into FLOAT.

FLOAT : Purpose is to keep a full battery bank while you still have access to sunlight. Giving you a full usable battery for the night. Due to LFP having such linear charge curve, if you set it below the resting cell voltage of 3.34v it will slowly drain the battery rather than keeping it full. Using 54v for me or 3.375v keeps the charge up and doesn't add much throughout the day to slowly overvoltage the system because it is always drawn back down on a daily basis ie at night.

Very good. More helpful info.

btw, a few days ago I actually re-configured my charging profile like yours (floating just above resting volts). I don't want to take any chances as I haven't balanced my array yet. Although I did do a "parallel cell balance" when I first received them, which was simply the act of using the bus bars to configure all the cells in parallel and let them sit for a day or two.

I have a specific reason for not balancing yet. Nor have I installed the BMS. I wanted to run the system for a couple of weeks and "get to know" the pack. I'm taking measurements when the cells have discharged in order to spot any "runts" in the litter. Obviously I'm monitoring that no cell falls below 2.7v or rises above about 3.5v.

One reason for this approach to has to do with the cell balancers I bought. I purchased balancers that use a distributed management architecture. There is no central control board, and no connection to the Classic.

Rather, these balancers all daisy-chain together. Instead of one balancer bleeding off voltage to keep a pre-set cap on cell voltage, all cells are talking to each other and are aware of pack voltage.

This seems a unique approach, and I am going to skip bottom and top balancing for now to see how well these devices maintain uniform voltage at all charge points.

http://www.electriccarpartscompany.com/3V-1S-Lithium-Lighted-Battery-Balancers

Thanx Cloud!

 :) NP

Did I mention that we are looking very seriously at making a B17 type of unit that is actually plug in Lion batteries?
Envision this: A B17 on top and two or three more B17 looking units below. That makes for a nice compact system.

Quote from: Robin on July 25, 2017, 12:48:47 AM
Did I mention that we are looking very seriously at making a B17 type of unit that is actually plug in Lion batteries?
Envision this: A B17 on top and two or three more B17 looking units below. That makes for a nice compact system.

How many AH of lithium are you talking about ?

Larry

So, the battery bank wouldn't be separate? More of an all in one easy peasy "tesla" power wall idea? Or did I miss the bus on this one...

Quote from: boB on January 01, 2013, 01:25:45 AM

Large Lithium type batteries pretty much already come with Battery Management System  (BMS) integration which is necessary to
balance all of the cells so that any one battery doesn't get hot or hog a charge.

What I've seen is that with this already in place, the controller simply has to either have the Classics' Absorb time
set to nearly zero OR, the BMS may have a control output that tells the Classic to stop and start its charging
via the Aux 2 terminal which now also acts as an input for this function.

Question if a MNwbjr is on aux2 can this still be used with two signal feed from a bms with the feature

Pretty cool, huh ??

We'll try to post some links for some of these as they pass by.  I have one or two somewhere already.

boB

Would the whiz bang still function if a signal from a bms was placed on the same aux port ? Or would the whiz bang have to be removed?

 whiz bang as I know is the only one to use that port , There is another AUX port in a Classic .

One WBjr per Aux port , but on the shunt , you can have 2 WBjrs & any other unit all piggybacked.

VT