Wrenches Mixing of batteries of the same sise and brand, older vs new maybe bepending on age and or abuse. Mixing of type or size of batteries, sorry i dont really care if the manufacture says its ok, Its not for me. I have tested batteries and BMS and even with everything right there can be an issue with them so why sdd to the possible issues. Jerry On Nov 20, 2015 2:07 PM, "Starlight Solar Power Systems" < [email protected]> wrote:
> Hi Allan, > > Yep…At first my thought was with the batteries in parallel, they > contribute equally to the load. Upon further thinking, this could not be > true because the voltage must stay the same across all terminals during > discharge. That can only mean the larger battery provides more AH than the > smaller at any depth of discharge. It must also be true that DoD percentage > of each battery is identical at any point in cycle. > > On charging, the reverse must be true again because of terminal voltage. > It’s obvious that this should never be done in series strings. So….why have > I always believed, preached and insisted “never mix battery sizes in the > same bank”? > > Battery wrenches, has anyone ever done or seen this done? (Allan, I’m not > even going to ask about your customer with five 6 volt batteries in a 24 > volt bank) > > Larry Crutcher > Starlight Solar Power Systems > > > On Nov 20, 2015, at 4:19 PM, Allan Sindelar <[email protected]> > wrote: > > Larry, > Nobody has responded to your question: "How can this possibly be OK for > the 75AH battery? And why would a battery manufacturer say this?" and like > you, it goes against everything that I have assumed. But to answer that > first question: when I look at, I wonder why it wouldn't work. With AGM > batteries you can tolerate both high and low charging C/ rates and long > absorption times. So it makes sense that as long as the voltage remains the > limiting factor and the array is large enough to allow routine long > absorption periods, it oughtta work just fine. > > Your thoughts? > 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 11/18/2015 5:09 PM, Starlight Solar Power Systems wrote: > > Just when I thought I was becoming a battery guru, this came up: A customer > asked me if he could purchase two different size 12 volt Lifeline (Concorde) > AGM batteries and connect them in parallel. Of course I told him this was a > bad idea and all his parallel batteries should be same make, age, size. A few > days later he called me back and said he talked to Lifeline battery and they > told him it was fine to mix any size of their batteries together. Knowing > that people sometimes hear wrong, I called Lifeline to inquire. The answer, > "yes, you can mix any of our batteries in parallel. We have tested that and > Concorde tested it and it’s no problem”. > > Stunned, I asked him if this was in writing anywhere and he said no but I > could test this myself. So battery wrenches, what will happen if I have an 8D > at 255AH paralleled to a group 24 at 75 AH and discharge this to 80% DoD? How > can this possibly be OK for the 75AH battery? And why would a battery > manufacturer say this? > > Larry > > > > _______________________________________________ > 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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