[RE-wrenches] Five L16s in a 24V string?

[Jerry Shafer]

I have18 on a 48 volt outback system just set the CC and chargrr up a
little. My concern about 5 on a 24 volt is how deep the batteries really
get charged,  7.5 v a battery is 37.5 and thats above the inverter
operating range same issue with nickle iron. There may not be good spec
gravity for long life and capasity.
Jerry
On Sep 30, 2015 7:44 PM, "Allan Sindelar" <allan at sindelarsolar.com> wrote:

> Wrenches, especially the grizzled ones,
> I was referred to a couple for off grid service about 75 miles from here.
> They have an older homeowner-built 24V system (that I haven't seen yet) and
> have lived with it for decades. They have ten L16s in two parallel strings.
> I questioned this when I first heard it, but the owner told me that the
> most positive cell is the one that always fails first, and he hates the
> effort of periodically rotating his batteries, so the battery nearest the
> positive cable has another L16 in parallel with only this battery. He
> explained that he has lived this way for thirty years. I don't yet know
> what life they have gotten from their battery sets, but until recently they
> lived on 750W of PV, and now have around 1kW - not a large array.
>
> I respectfully replied that in nearly thirty years in the field, this is
> the first time I had heard of this approach. My own experience is that
> while sometimes I had sometimes seen marginally more water consumption in
> the lead positive cells as they aged, when I had tested for failed cells in
> old strings, the failed cells tended to be randomly located, and not
> frequently enough at the positive end to suggest a pattern. I had also long
> ago read (Surrette's manual?) that rotating the lead cell is good practice,
> but unless a system has a single series string, wired to make this
> possible, nobody ever did this rotation, and it didn't appear to make a
> noticeable difference in long-term performance.
>
> Has anyone else heard of this approach? Is there validity to the logic?
> What can I learn here that I didn't know?
> Thank you,
> Allan
> --
>
> *Allan Sindelar*
> allan at sindelarsolar.com
> 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: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive:
> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20150930/aeddaca1/attachment-0002.html>