[RE-wrenches] How Best to Load Test 2 V Cells

[Jeff Clearwater]

Thanks Dave - yes I've done whole pack load testing.  The deal with this 
pack though is that it is so remote and the expense of "just replace the 
pack" in terms of shipping and labor is extreme - (tiny Bahaman island 
with only regular small boat access}

And if it was toward the end of the pack's life anyway I'd not mess 
around - but with only 600 well documented cylces on a $25K pack - and 
with probably half that again in shipping and labor to replace - I'm 
needing to carefully document the lagging cells for either a warranty 
claim or at least to make good decisions going forward.

It's easy to access the cells as this is an EnergyCell AGM stack with 
easily accessible terminals and removable terminal bars.

If we replace we'd go LFP - on the order of 100 KWHrs.  So no small 
decision for the customer - so worth the testing.

Thanks!

Jeff Clearwater
Village Power Design
www.villagepowerdesign.com <http://www.villagepowerdesign.com>



> Dave Angelini Offgrid Solar <mailto:offgridsolar at sti.net>
> July 14, 2021 at 10:32 AM
>
> I can ask my battery guy! He is the best with AGM and a dealer for 
> full river and concord. He does this alot! Saves a bunch. He always 
> says that most of the warranty is just a full/corrective charge and 
> 80% are good. Undercharging is the problem. Very very few are 
> overcharged. His words! I just replace the bank, no time to play with 
> this stuff.
>
> However, I just do the same thing I do with any bank of individual 
> batteries. I put a large load on the bank with the inverter and look 
> at each cells voltage. You may have done this...
>
> The hard part is, depending on the make, is pulling the cell and doing 
> a full charge and EQ if it is the make that allows it.
>
> The other hard part is just getting batteries these days. I just heard 
> Trojan is 8+ months out. You know what Steve from RollsSurrette has 
> said. 8 weeks I think.
>
> The easy part, what make is your cell?
>
> *Dave Angelini Offgrid Solar
> "we go where powerlines don't"
> http://members.sti.net/offgridsolar/
> e-mail offgridsolar at sti.net <mailto:offgridsolar at sti.net>
> text 209 813 0060*
>
> On Wed, 14 Jul 2021 10:16:31 -0700, Jeff Clearwater 
> <jeffc at villagepowerdesign.com> wrote:
>
> Jeff Clearwater <mailto:jeffc at villagepowerdesign.com>
> July 14, 2021 at 10:16 AM
> Hey Good Folks,
>
> I've got a 2300 AH AGM pack of 2 Volt cells that is showing signs of 
> premature aging (only 600 cycles) and I need to test the AH capacity 
> of each cell to help the customer make decisions going forward of 
> whether to replace individual lagging cells or the whole pack.
>
> What equipment have folks used to do AHour tests on 2 Volt 2300 AH 
> cells?  I've done plenty of load testing on 6, 12, 24 and 48 volt 
> packs as a whole but am not sure what's my best approach is for 2 volt 
> individual tests.
>
> I know I could put a  resistance load and then use an AHour integrator 
> unit - but does anyone know of what unit and what resistive load I'd 
> use at 2 volts?  That would be a large device at that voltage to get 
> any appreciative wattage! - I'd like to do a 10 hour test at most.
>
> I see 2 V test units on the web but they only appear to be hooked up 
> for a small amount of time - so they can't be testing full to empty 
> discharge AHours.
>
> Thanks!
>
> Jeff Clearwater
> Village Power Design
> www.villagepowerdesign.com <http://www.villagepowerdesign.com>
>
>
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