First time I've heard of something like this since starting in the off-grid business in 1994. Closest I've done to 'rotating' batteries is switching which corners of a series/parallel bank are the main DC connectors. I have noticed, on some occasions, the end cells may use a bit more water. As for cell failures on strings, ends, middles, no particular pattern here with my installations. I *would* say those main end connections are the most important to keep super clean and maintain really good,low resistance connections as in series/parallel setups these connections have the most heating/cooling from higher amperage. At least your client has a couple easily deployable extra batteries if another somewhere in the bank fails! Especially with an aging battery bank.
As for the initial confusion on how these extras were wired in, thanks for the diagram. Slightly off topic, I have been running my home/office on NiFe cells for 5 months now and I feel pretty confident about working around their idiosyncrasies. My Outback and Midnite charge controllers couldn't care less what the output voltage is, but the Magnum inverter goes into panic mode when asked to reach the sweet spot of 1.65v per cell off of the backup generator, it assumes the world is ending at 1.6v per cell. Hopefully a Magnum firmware upgrade in the future can fix that. Best regards; Dan Fink Adjunct Professor, Ecotech Institute IREC Certified Instructor™ for: ~ PV Installation Professional ~ Small Wind Installer Executive Director, Buckville Energy NABCEP / IREC / ISPQ Accredited Continuing Education Providers™ 970.672.4342 On Thu, Oct 1, 2015 at 1:22 PM, Allan Sindelar <[email protected]> wrote: > Larry, > I don't know the answers to these questions, as I haven't yet been to the > site. This is a new customer, referred to me by another company that > doesn't do off grid - at least, not off grid that works. When he told me > how they were set up on the phone, my gut response was "this sounds dumb, > or I would have heard about it before", but I kept quiet and only gently > said what I wrote in my post. I posted this question in order to have the > Wrenches support for any position I offer when I go there next week. > > Also, the batteries weren't an issue in asking me to do a service call. I > don't yet even know what the issues are, other than their mention of > wanting a backup generator and wanting me to check configuration on an > XW4024 that they recently added. I had been told that they had "ten fork > lift batteries", which isn't possible with 24V, so I asked questions about > that and that led to this thread. > > If I can get any useful information about the batteries I'll post it here. > I'll try to check SG's and maybe even some sort of load test, but likely > off the clock, as battery trouble wasn't a presenting issue when they asked > for a service call. > > Larry, nice drawing below. What did you use, as I need to learn it too? > Allan > > *Allan Sindelar* > <[email protected]>[email protected] > NABCEP Certified PV Installation Professional > NABCEP Certified Technical Sales Professional > New Mexico EE98J Journeyman Electrician > Founder (Retired), Positive Energy, Inc. > *505 780-2738 <505%20780-2738> cell* > > > On 10/1/2015 1:04 PM, Starlight Solar Power Systems wrote: > > Since multiple batteries failed ("the one that always fails"), did he buy > one new battery each time and tie it to the old failing one? Or, did he > start with a new bank and create the parallel at that time? Since he’s an > “old timer” he may be mixing different age batteries in the bank. I see > this often in Mexico. If that’s the case, it will be difficult to find any > cause of failure. > > > On Oct 1, 2015, at 10:26 AM, Allan Sindelar < <[email protected]> > [email protected]> wrote: > > Jerry, > The five batteries aren't in series. I thought I made that clear, but > maybe not. Two are in parallel at 6V at the positive end, and then that > pair are in series with the remaining three. > Allan > > *Allan Sindelar* > <[email protected]>[email protected] > NABCEP Certified PV Installation Professional > NABCEP Certified Technical Sales Professional > New Mexico EE98J Journeyman Electrician > Founder (Retired), Positive Energy, Inc. > *505 780-2738 <505%20780-2738> cell* > > > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & > settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/[email protected]/maillist.html > > List rules & etiquette:www.re-wrenches.org/etiquette.htm > > Check out or update participant bios:www.members.re-wrenches.org > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/[email protected]/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > >
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