Lithium battery charge profiles

[offgridQLD]

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.

[boB]

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

[dgd]

.. 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

[boB]

.. 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

[mtdoc]

A Mk2 Classic optimised for use with LiFePO4 batteries ?

No,  just a firmware update!

[dgd]

A Mk2 Classic optimised for use with LiFePO4 batteries ?

No,  just a firmware update!

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 

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

[cpm]

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.

[boB]

The firmware has the vid/kb drivers built in.

Video/Keyboard drivers ?  Where is this ?

boB

[mtdoc]

A Mk2 Classic optimised for use with LiFePO4 batteries ?

No,  just a firmware update!

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 

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!

[boB]

A Mk2 Classic optimised for use with LiFePO4 batteries ?

No,  just a firmware update!

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 

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

[cpm]

but but but,

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

[boB]

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

[dgd]

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

[mtdoc]

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....

[dgd]

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