[RE-wrenches] Batteries in parrallel Failure

[R Ray Walters]

I like the fused parallel idea; could save the system, and would make battery troubleshooting nice.
I would suggest #6 jumpers with 50 to 60 amp breakers,  so the system could be operated on just a few strings if needed.

R. Walters
ray at solarray.com
Solar Engineer




On Apr 19, 2011, at 8:29 PM, Darryl Thayer wrote:

> Batteries in parallel, How to protect from catastrophic failure.
> I just got contacted to commission a solar system off grid not of my design.   Eight battery strings in parallel, AGM batteries, 24 volts @ 120 AH each string (two 12 volt in series)  New system, new batteries, Silent POwer Inverter.  Two kW DC array.  generator to charge through Silent power.  (present installer is not sure how to do final set up and testing) 
>  
> I am most concerned about 8 batteries in parallel, (especially since last week a set of AGM burned up having 5 in parallel Owner had no way to break the paralleling of the batteries, she could only stop the chargeing)   What I am proposing for your review is requireing the installtion of  two combiner boxes Midnight solar with a breaker in each battery string, using about 3' of #10 to connect each battery string to the combiner box.  This way if a battery failed and the paralled strings were to "dump" into the failed battery it would trip the breaker.  I was thinking of using a 30 amp breaker in each string. The main breaker is set at 240 amps. 
>  
> Ideas Please?  
> 
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