[RE-wrenches] Battery cell shorting
Kirk
kirk at vtsolar.com
Sat Oct 23 17:15:58 PDT 2010
Jamie et al-
Bank is -8- Rolls T12-250, 12 v, 200 ahr @ 20 hr rate. So -4- series
strings in parallel, 800 ahr @ 24 vdc. So C10 charge rate of 80 amps.
SW4024 charger is 120a max, so worst case about C/6.7 rate. Of course
this rate is not at all constant, we all know. I have not yet seen the
bank this time or have access to your battery pics, as I am away.
Kirk Herander
VSE
On Oct 23, 2010, at 2:53 PM, Darryl Thayer <daryl_solar at yahoo.com>
wrote:
> Thanks Jamie I find your input to be most valuable, the photo shows
> how the plate material has been "blown off the positive grid" a sure
> sign of overcharging and overcharge rate
> Daryl
>
> --- On Sat, 10/23/10, James Surrette <james at surrette.com> wrote:
>
> From: James Surrette <james at surrette.com>
> Subject: Re: [RE-wrenches] Battery cell shorting
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>,
> kirk at vtsolar.com
> Cc: "Serge Bourque" <Serge at surrette.com>
> Date: Saturday, October 23, 2010, 10:15 AM
>
> Hi Kirk,
>
> I know our brand is mentioned, so I don't want to sound as though we
> are ducking a failure. However, suspect from your tone, you agree
> 3 sets in 5 years represents a system problem and not battery defects.
>
> In order for these units to fail, I echo earlier statements that
> high charge rates relative to battery size is probably the cause.
> However, this could be compounded by high usage rates relative to
> bank size, i.e, over cycling and overcharging. Once you have a cell
> failure, then the overcharging issue is further exacerbated due to
> the drop in cell voltage - hence the high temp / bulging which will
> destroy any bank.
>
> If you have any tear down pics, I would happily review. Suspect you
> will see something like the attached (right side) on your positive.
> Positive on the left is a "well used" battery. The positive on the
> right has been severely overcharged.
>
> Hope this helps,
>
> Jamie
>
>
>
>
>
>
>
>
> >>> jay peltz <jay at asis.com> 10/23/2010 12:02 PM >>>
> Hi Kirk,
>
> Can you fill us in on how many batteries are in each set that was
> ruined?
>
> thanks,
>
> jay
>
> peltz power
> On Oct 22, 2010, at 12:39 PM, Kirk Herander, VSE wrote:
>
>> Hello,
>>
>> I have an off-grid battery / generator / SW4024 system which has
>> destroyed -3- sets of batteries in the last five years. By
>> destroyed I mean multiple batteries having shorted cells, with
>> electrolyte literally steaming out of them and bulging badly. The
>> last two sets were Rolls T12-250’s. The first set was Trojan
>> T105’s. This system has no solar, and I would not be surprised if
>> the generator ran 10-12 hours a day charging the batteries, for th
>> e residents don’t believe in energy efficiency. I could see the ba
>> tteries cycling to the point of being useless after a couple years
>> , but the scary thing is the condition I’ve witnessed multiple tim
>> es now. Any ideas as to why this has happened repeatedly across di
>> fferent brands of batteries? Thanks.
>>
>> Kirk Herander
>> Vermont Solar Engineering
>> 802.863.1202
>> NABCEP(tm) Certified Solar Installer
>> NYSERDA-eligible Installer
>> VT Solar Incentive Program Partner
>>
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