[RE-wrenches] Battery cell shorting

[James Surrette]

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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