Here is a good reason to spec out 2 volt cells, all of the manufactures have DC input windows that will allow you to remove 2 volts while getting a replacment.Conversly we have also installed 26/50 volt battery banks for hi inrush loads. Remember when you sized BB w/o charge controllers?
-----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters Sent: Tuesday, December 01, 2009 8:20 PM To: RE-wrenches Subject: Re: [RE-wrenches] concord batteries, EQUALIZE Them! Yes, I've had a 48 v system survive a dead cell (Outback inverter), but 24 or 12 v systems are done. So I guess the Sunnyboy can go down to 42 V? R. Walters r...@solarray.com Solar Engineer On Dec 1, 2009, at 3:41 PM, Richard L Ratico wrote: > I believe the Sunny Island 5048 can be configured to remain "online" > with up to three cell failures. (Page 90, Sunny Island Manual). Of > course, it is a 48 volt inverter. > > Dick Ratico > Solarwind Electric > > --- You wrote: > I used to think that one string was optimal; until I had a single cell > failure take out an entire system for weeks. (try operating a 24 v > system at 22v! ) I now think that 2 parallel strings is optimum, 3 is > OK, and 4 is max. At 4 parallel strings, we start spending more time > looking to make sure all connectors are the same exact length etc. to > insure equal operation. But of course how do you account for varying > internal resistance of the batteries......?? I've done 4 parallel > strings at 144 DC of sealed batteries on an electric vehicle, but we > were very careful with our resistances, I even switched to smaller > wire, on closer strings, and calculated out the exact resistance, so > all strings were theoretically equal. This set actually just died, but > achieved its manufacturer's predicted cycle life. (B&B battery, 350 > cycles to 80% DOD) So if you're careful, 4 strings can work well. > Worst I've seen was 20 golf carts paralleled in a 12 v system, (10 > strings) and they didn't pull the main connections from across the > set, just connected to one end. The results were very predictable, > with the furthest batteries being chronically under charged, and the > closest ones being over cycled to a premature death. > > Ray Walters > --- end of quote --- _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@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@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@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
