[RE-wrenches] Battery cell shorting

Sat Oct 23 22:36:37 PDT 2010

I have a client right now doing a last ditch heavy equalizing cycle to try to save his 5 year old, 24 volt bank of 8 L-16's. One of the two series strings has a weak cell... so the other string is boiling away. He is charging for 2 hours with 2 hours rest to not overheat the charged cells. Too bad that last low cell cannot be charged alone. 

Is it hard on the charged cells to continue to charge at ~C15 rate Like this during a eq cycle?

Todd

On Saturday, October 23, 2010 11:53am, "Darryl Thayer" <daryl_solar at yahoo.com> said:

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 the residents don’t believe in energy efficiency. I could see the batteries cycling to the point of being useless after a couple years, but the scary thing is the condition I’ve witnessed multiple times now. Any ideas as to why this has happened repeatedly across different 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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