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 [email protected] 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: [email protected] > > 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: [email protected] 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
