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On 5/31/2011 11:25 PM, Tom Elliot wrote:
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<div>Bob,</div>
<div> </div>
<div>I totally understand the concern about multiple strings
*if the strings are connected across the battery bank* as
had always been the tradition in off-grid installations. My
own experience with such a bank in my system showed why
when I had a single cell get to near meltdown. I was lucky
to find it. <br>
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<br>
<br>
This might be a good reason for an installer to have one of those
FLIR (or similar) thermal imager cameras. They're a bit on the
expensive side, but could<br>
really be helpful for so many things. Even just to know if you
have left a nut loose (under load of course)<br>
<br>
boB<br>
<br>
<br>
<br>
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<div> Maintenance is another reason, such banks are far more
difficult to maintain. But I think those concerns are
ameliorated a great deal with a buss bar installation and
once I did that I never had another problem and found the
battery bank much easier to maintain because the strings no
longer had to be right next to each other. Heck, it would
be possible to put each series string in its own box for
that matter. And with the inclusion of string fuses that
reduces problems even further. </div>
<div> </div>
<div>When living with an off-grid system my biggest concern
was system reliability and redundancy and the idea of a
single string failure was a big worry which is why I never
would consider it.</div>
<div> </div>
<div>Tom</div>
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<div style=""><b>From:</b> <a moz-do-not-send="true"
title="boB@midnitesolar.com"
href="mailto:boB@midnitesolar.com">boB Gudgel</a> </div>
<div><b>Sent:</b> Tuesday, May 31, 2011 8:16 PM</div>
<div><b>To:</b> <a moz-do-not-send="true"
title="re-wrenches@lists.re-wrenches.org"
href="mailto:re-wrenches@lists.re-wrenches.org">RE-wrenches</a>
</div>
<div><b>Subject:</b> Re: [RE-wrenches] 24 volt Battery
Bank comparison</div>
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<br>
OK, I've been hearing for years now that one battery string
is best and maybe two but no more should be used.<br>
<br>
What is the reason for this fear ??? What is the
experience with multiple strings in parallel ??<br>
<br>
If it is because of current sharing of the strings, that
shouldn't be an insurmountable problem if the wiring is done
right.<br>
<br>
If it has to do with the possibility of fire, which Darryl
mentioned, seems that series string fuses could mitigate the
possibility of that issue, if because of shorted cells, just
like PV combiners.<br>
<br>
Or maybe it has to do with the trouble of getting into the
middle of a pile of batteries ? Use battery boxes ?<br>
<br>
The strings are in parallel and so they all get the same
voltage, theoretically anyway if the connections are good.<br>
<br>
I would think that the more strings, the LESS stress on
individual batteries, not more. The current in each battery
should be less than it would be I would think.<br>
<br>
So what is the real experience ?? <br>
<br>
Is a battery balancer the answer ??<br>
<br>
Thanks,<br>
boB<br>
<br>
<br>
<br>
<br>
<br>
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cite="mid:C956D9BB-02FF-4821-9909-AF40789AFBF1@fafcosolar.com"
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<div><br>
On May 31, 2011, at 8:23 PM, "Wayne Irwin" <<a
href="mailto:wayne@pureenergysolar.com"
moz-do-not-send="true">wayne@pureenergysolar.com</a>>
wrote:<br>
<br>
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<blockquote type="cite">
<div>I think the verdict is<b> 12</b> - Rolls 2-YS-31
2430 AH @ 20 HR (one string) and one dry spare in
storage is the best case scenario!<br>
<br>
<font color="#76923c">Wayne Irwin</font><font
color="#76923c">, EE<br>
Director of Engineering<br>
</font><font color="#76923c">Pure Energy Solar
International Inc. </font><font color="#76923c"><br>
</font><font color="#76923c">State Licensed Solar
Contractor</font><font color="#76923c"><br>
</font><font color="#76923c">License # CVC56695 </font><br>
<a href="mailto:Wayne@PureEnergySolar.com"
moz-do-not-send="true">Wayne@PureEnergySolar.com</a>
<br>
<a href="http://pureenergysolar.com"
moz-do-not-send="true">http://pureenergysolar.com</a>
<br>
<font color="#76923c">352 377-6527 Office</font><font
color="#76923c"><br>
</font><font color="#76923c">352 336-3299 Fax</font><font
color="#76923c"><br>
</font><font color="#76923c">352 316-1637 Cell</font></div>
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