Author Topic: Battery System For High End Customer?  (Read 239 times)

Ron Swanson

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Battery System For High End Customer?
« on: December 07, 2017, 01:13:13 PM »
Greetings folks.

I have been looking for a forum like this a long time, and just now found it.

Small off grid company here.  Mostly servicing small customers with one or two FX inverters and a variety of charging and if anybody will listen, it is always a Solar One FLA bank of appropriate size.

PoCo hookup costs are extremely high these days.  We see more and more high end customers coming around wanting a system they can just run and not have to mess with themselves and can operate more or less like a grid tied system.  I believe we have the inverter, generator, panel, charge controller portion of this more or less settled.  (The B17 looks like a great addition to this, though)

But batteries are a sticking point.  What do we do for the customer who can afford to get what is best in the long term.  Let me lay out the different ideas as I see them.

1. Solar One (or FLA industrial type)
advantages:
-long life
-low cost (relatively)
-proven
-robust to accidental abuse
disadvantages:
-watering
-acid mist

2. C&D Lead Calcium or equivalent
advantages
-advantages of flooded without the acid spray, etc.
disadvantages
-high cost
-still need watering

2. AGM or other sealed lead acid
advantages:
-zero maintenance
disadvantages
-we have seen more than one temperature comp. device go bad and wreck them-solutions for this?
-"brittle" - abuse of any kind seems to wreck them

3. LiFePO (brands please?)
advantages
-people seem to say they are great
-BMS prevents breakage as complained above
-no maint.
disadvantages
-we have never seen one nor know of anybody who has one
-assume cost is a disadvantage but don't really have a handle on costs due to lack of experience
-general lack of experience on non-experimental systems

Keep in mind the financial calculation of paying us or somebody to come out and water batteries once a month is a perfectly good option as well, gets us on site to hopefully catch problems before they go out of control.

Hopefully this post was formulated well enough to describe what we are after.

Robin

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Re: Battery System For High End Customer?
« Reply #1 on: December 07, 2017, 05:15:28 PM »
Ron, you didn't say what the intent is? Do you intend to take a normal house off-grid? That is tough. That is expensive and normally peoples expectations are unreasonable. Once everything is tallied up, they decide to stay on-grid.

Flooded batteries are still the biggest bang for the buck. They are also very forgiving.
Lead Calcium are telephone batteries meant to be floated all the time. They are not suitable for deep cycling.

AGM's are fine. Charging sources these days are good enough to not ruin them. Some charge controllers can be set such that even if there is a problem with a battery temp sensor, the batteries will not be over charged. The Classic has those features. I am not sure about the others?

Lithium can actually be on a par with flooded batteries if they last through their expected life, but they are still very new and we do hear of horror stories.

My experience tells me that grid connected homes will never water their own batteries. It just doesn't happen. Heck, I am grid connected. That is why I have AGM's. I did check my golf cart battery water a year ago, or was it two? See what I mean, and I know better.
Robin Gudgel

Ron Swanson

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Re: Battery System For High End Customer?
« Reply #2 on: December 07, 2017, 08:03:32 PM »
Thank you, Robin.

We cater to off grid people only.  We try to talk them into grid-tied if possible.  This is for the semi-mansion that some people want to build out in the middle of the woods far from anywhere.  Not a specific project.  Just gathering info so we can have it when they call, someday.

I am just fishing around right now for what the best battery solution is for somebody who has, for instance, 3 Radians powering the house.

I like the idea of AGMs.  It is just that all the AGMs I have seen in my travels are now in the scrap heap having been replaced by flooded.  Since something or other wrecked them.

Tell me more about temp sensor protection.  Suppose we had 2 Radians and 3 Classics.  How would that happen if one of the sensors failed?

CDN-VT

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Re: Battery System For High End Customer?
« Reply #3 on: December 07, 2017, 08:09:01 PM »
Welcome Ron

& too funny , but True Robin
Canadian Solar 350W 37.6 VOC  30.6 VMP 8.22 ISC 7.87 IMP ,-15 c +30c max  4 strings in 2 in Series for 24v Classic 150 -1020 Ah  Freezers & fridges ~~~ Second Array same panels of 3sx3 parallel for 24 V Classic 150 -440 Ah Outback Barns & out blds.
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Westbranch

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« Reply #4 on: December 07, 2017, 09:54:39 PM »
Look into C&D AGMs,

mine have been  unintentionally abused (long winter, left Classic CC hooked up and a lot of snow) down to 8V in a 24V pack but cold temps,  been 2 full years so far since low V met the charger and PV's sans snow... no sign of any significant loss of capacity so far.

I would go that way again but I am waiting for LiFePo4 to prove itself in a all in one pack ~ 10kW X 2
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub Hughes 1100 Sat. Modem
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Matrix

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Re: Battery System For High End Customer?
« Reply #5 on: December 07, 2017, 11:12:12 PM »
@Westbranch ; where were you able to get C&D AGMs?  I am having a hard time locating a retailer.   Guessing they are more of an industrial battery?
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REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter latest firmware / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 10' of 4/0 cable / 24 volt system / Grid-Assist Off-Grid / Need 3200Whs Daily

Ron Swanson

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Re: Battery System For High End Customer?
« Reply #6 on: December 08, 2017, 12:53:31 AM »
I am sure there are a number of sealed products that would work but I am most concerned about how to protect them when something goes awry with the charging.

Basically with programming and such we are trying to make all our inverters and charge controllers interact smoothly to build our own BMS.

I would much rather have even a simple lead acid battery have its own BMS which is there solely to protect and manage the battery.  The dollars involved scares me too much.

dgd

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Re: Battery System For High End Customer?
« Reply #7 on: December 08, 2017, 04:31:09 PM »
What is a high end customer?
Why would the battery type they need differ from the needs of any other customer?
dgd
Classic 250, 150,  20 140w, 6 250w PVs, 2Kw turbine, MN ac Clipper, Epanel/MNdc, Trace SW3024E (1997), Century 1050Ah 24V FLA (1999). Arduino power monitoring and web server.  Off grid since 4/2000
West Auckland, New Zealand

Ron Swanson

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Re: Battery System For High End Customer?
« Reply #8 on: December 08, 2017, 04:40:54 PM »
What is a high end customer?
Why would the battery type they need differ from the needs of any other customer?
dgd

Because most mom and pop customers with a 900 square foot cabin and a single FX take care of their own batteries.  They don't mind going out and shining flashlights and adding water to a flooded bank, and gathering a party of neighbors when it is time to move heavy objects.

What I am talking about is usually a house worth $1MM+, sometimes a lot of +, and the owner does not want, nor should he need, to do anything.

Having us come out monthly and water a FLA bank is a perfectly viable option if it makes economic sense.  But there are a lot of variables that go into the financial calculation.

Along with practical consideration which is why I am asking this question.

See this post: http://midniteftp.com/forum/index.php?topic=3640.0 post #5

What is the battery bank shown there?

Also one other idea I neglected, what about Absolyte?  So far all we have seen of them has been wrecked banks too.  But they may have been salvage.

Matrix

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Re: Battery System For High End Customer?
« Reply #9 on: December 09, 2017, 04:33:26 PM »
That is one Hi Powered battery bank in that pic  :o
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REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter latest firmware / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 10' of 4/0 cable / 24 volt system / Grid-Assist Off-Grid / Need 3200Whs Daily

RossW

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Re: Battery System For High End Customer?
« Reply #10 on: December 09, 2017, 06:50:48 PM »
Hey, that's MY battery bank!!!

That is also my old bank, and honestly guys - given my time over, I would not do it that way again.
Those are 500AH 2V AGM cells, configured as three 500AH/48V packs. The cells weigh 33kg each near enough.

They were pre-owned cells, but they really didn't like the fairly deep cycles they were getting, and the fact that I didn't have sufficient monitoring. Hint: anyone who thinks merely monitoring the terminal voltage of the pack is good enough, is fooling themselves.

Once a few cells start to go, they rapidly self-destruct. I lost a couple of cells and had to decommission one of the 3 packs to get "spare" cells to prop up the other two strings. It didn't take very long for the (now) disconnected remaining "spare" cells to bulge and deteoriate to the point they became merely scrap lead. I was then back to no spares, and the next cell that failed meant I was down to one bank. Of course, it was working even harder now because of the reduced capacity.

I bought 16 x 300AH LFP and transitioned from the one 500AH AGM pack to the LFP as primary and AGM as "backup". After 6 months, the old AGMs went as scrap. A single 300AH LFP outperformed even two banks of AGM in every regard I cared to consider. They were stiffer, they took charge better, the inverter was happier with them, they were 1/8 the volume and 1/10 the weight. They are more efficient too.

I tried to get another bank of the same cells due to additional equipment here which needed more overnight power storage, but the company had disappeared. I purchased another 600AH of a different brand. The two banks are now paralleled giving me basically 900AH of LFP, and they very rarely go below 53.0V and never above 55.5V. I can use more power, and survive much longer periods of bad weather than I ever could with the AGMs.



Edit: there was a pic of part of my new (600AH) pack here: http://midniteftp.com/forum/index.php?topic=3640.msg35713#msg35713
They are 16 series groups of 3 x 200AH cells in parallel.
« Last Edit: December 09, 2017, 06:58:24 PM by RossW »
3600W on 6 tracking arrays.
7200W on 2 fixed array.
Midnite Classic 150
Outback Flexmax FM80
16 x LiFePO4 600AH cells
16 x LiFePO4 300AH cells
Selectronics SP-PRO 481 5kW inverter
Fronius 6kW AC coupled inverter
Home-brew 4-cyl propane powered 14kVa genset
2kW wind turbine

Ron Swanson

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Re: Battery System For High End Customer?
« Reply #11 on: December 09, 2017, 07:42:44 PM »
Robin said "Lithium can actually be on a par with flooded batteries if they last through their expected life, but they are still very new and we do hear of horror stories."

So we are still leery to install them for a paying customer, lest something terrible happen and we be left holding the bag.

I suppose a lithium vendor would have only their own BMS to blame, though, since they come as a package deal, correct?

As for AGMs, I forgot to include Outback.  Only seen one so far, very small, little old lady who I would be shocked if went over 15% DoD at any time.

We may also be able to get good deals on Deka Unigy.  Never seen them in the field yet.

Thoughts?

Westbranch

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Re: Battery System For High End Customer?
« Reply #12 on: December 09, 2017, 08:31:59 PM »
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub Hughes 1100 Sat. Modem
Cotek ST1500 Inv  want a 24V  ROSIE Inverter
OmniCharge3024  Eu1/2/3000iGens
West Chilcotin 1680+W to come

mike90045

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Re: Battery System For High End Customer?
« Reply #13 on: December 09, 2017, 10:58:56 PM »
Li batteries with their own BMS, generally want the BMS to interact with the charger, so as individual cells fill up, and the Bleeders kick in, the Charger will throttle back and not BBQ the bleeders or their cells.

Tossing a generic BMS & 2Amp Bleeders onto a pack being charged with 20 amps, simply means when the BMS sees a full cell, and turns on the 2A bleeder, that cell is still getting 18A pumped into it.   All the parts have to be able to work with each other.
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RossW

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Re: Battery System For High End Customer?
« Reply #14 on: December 10, 2017, 07:33:41 AM »
Li batteries with their own BMS, generally want the BMS to interact with the charger, so as individual cells fill up, and the Bleeders kick in, the Charger will throttle back and not BBQ the bleeders or their cells.

Bleeders and "backing off". Ughh! It seems to me oh so familiar, like the "equalize until they're thoroughly cooked" mentality of FLA. Probably works for those who are significantly over-paneled or grid-tied, but in many solar installs, this really isn't ideal. Cells get charged, but perhaps not far enough for them to all get fully charged, then discharged again, then recharged but again falling short - and you end up with the lowest cells never getting full and early failure.

I went with charge balancers - a common AC bus, and each cell having a small bidirectional inverter. Any cell that's below the average will take a little charge from all the others. Any cell that's a little above the average will contribute a little more to everyone else. Cells are balancing continuously - while charging, while discharging and while just sitting. They're all kept to within a few millivolts. (Specs say 10mV, my measurements over the last 3 years seem to suggest about 2mV in practice)

3600W on 6 tracking arrays.
7200W on 2 fixed array.
Midnite Classic 150
Outback Flexmax FM80
16 x LiFePO4 600AH cells
16 x LiFePO4 300AH cells
Selectronics SP-PRO 481 5kW inverter
Fronius 6kW AC coupled inverter
Home-brew 4-cyl propane powered 14kVa genset
2kW wind turbine