[RE-wrenches] Batteries in parrallel Failure

[Tom Elliot]

The broken record will now repeat himself yet again.  Bussbars are the way to go, not across battery terminals but individual strings connected to a central positive and negative buss from which the inverter connection then runs.  This allows fusing of each individual connection and also allows for smaller positive cables and no need to have identical length parallel cables since each string is independently connected.  It’s what telecom installations use.  The Telecom guys who showed me how to do it literally laughed when told about paralleling across battery terminals.  They then told me they considered it profoundly stupid and dangerous and since I had just avoided a meltdown myself by catching a bad cell before complete failure I got the message pretty quick.

Really guys, this is amazingly simple and yes, it may mean a bit more cabling and another component but from a safety standpoint those considerations are pretty minor and cheap insurance against disaster.

Tom



From: R Ray Walters 
Sent: Tuesday, April 19, 2011 6:01 PM
To: RE-wrenches 
Subject: Re: [RE-wrenches] Batteries in parrallel Failure

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?  



------------------------------------------------------------------------------

  _______________________________________________
  List sponsored by Home Power magazine

  List Address: RE-wrenches at lists.re-wrenches.org

  Options & settings:
  http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

  List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

  List rules & etiquette:
  www.re-wrenches.org/etiquette.htm

  Check out participant bios:
  www.members.re-wrenches.org





--------------------------------------------------------------------------------
_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org




--------------------------------------------------------------------------------

No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1321 / Virus Database: 1500/3584 - Release Date: 04/19/11
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20110419/03d5f7a7/attachment-0003.html>