<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Hi Dan,<br>
<br>
No definitive suggestions, but kudos for making it a learning
experience for <u>all</u>. Great analytical technique. Hopefully
you gain more credibility with the kids as a result of your candor.<br>
<pre class="moz-signature" cols="72">Bill Loesch
Solar 1 - Saint Louis Solar
314 631 1094</pre>
<div class="moz-cite-prefix">On 11/22/2015 8:49 AM, Dan Fink wrote:<br>
</div>
<blockquote
cite="mid:CAF+3Lndfw0mrVjeTZRzpur89wdYxPS-Hbg1mHRR978+15x17bw@mail.gmail.com"
type="cite">
<div dir="ltr">Esteemed Wrenches;
<div><br>
<div>I'm looking for input on what could be going on with a
battery bank at the college I teach for. It's a stand-alone
system with 4 Trojan 12v T-1275 in series / parallel for
24v, 660w of PV, running only a drainback solar hot water
system for space heating. So, 3 pumps and 3 DTCs, max load
100 watts and doesn't run all that often, outback CC is
usually in float. The batteries are only 2.5 years old and
are regularly maintained.</div>
<div><br>
</div>
<div>My lab class tested and maintained the battery bank last
week, and on one battery there was one cell, in the middle
of the battery, with a SG so low it wouldn't even register
on our refractometer or midnite hydrometer. That battery
reads about 0.2v lower than the others. All the other cells
in that battery read reasonable SG, with 2 cells on the
downstream side reading SG slightly low, but still in
reasonable range. This was of course all before topping up
the electrolyte with distilled water.</div>
<div><br>
</div>
<div>Our troubleshooting exercise looked at:</div>
<div>~ Measurement error? Nope, I was right there supervising
and 2 different lab classes got the same results with 2
different instruments;</div>
<div>~ Stratification? A suspicion especially since the system
is usually in float. We equalized twice, no change in SG. I
DID hear that likely this was the first time the batteries
had ever been equalized, but no way to know for sure.</div>
<div>~ Spilled electrolyte from tipped battery replaced with
water by a previous instructor's class? Can't see this, all
the other cells would have lost electrolyte too;</div>
<div>~ A student accidentally discharged electrolyte into the
bucket instead of back in the cell, then was replaced by
distilled water when topping up? I can't see that either,
the midnite hydrometer needs only a small sample.</div>
<div><br>
</div>
<div>So, I'm left with "likely we have a cell that is failing
for some reason" and students secretly smug that the
professor is also stumped.</div>
<div><br>
</div>
<div>Any ideas?</div>
<div><br>
</div>
<div><br clear="all">
<div>
<div class="gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div><span
style="font-size:12.8000001907349px">Dan
Fink</span>
<div style="font-size:12.8000001907349px">Adjunct
Professor, Ecotech Institute</div>
<div style="font-size:12.8000001907349px">IREC
Certified Instructor™ for: </div>
<div style="font-size:12.8000001907349px">~
PV Installation Professional</div>
<div style="font-size:12.8000001907349px">~
Small Wind Installer</div>
<div style="font-size:12.8000001907349px">Executive
Director, Buckville Energy</div>
<div style="font-size:12.8000001907349px">NABCEP
Accredited Continuing Education Providers™<br>
<a moz-do-not-send="true"
href="tel:970.672.4342"
value="+19706724342"
style="color:rgb(17,85,204)"
target="_blank">970.672.4342</a></div>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
List sponsored by Redwood Alliance
List Address: <a class="moz-txt-link-abbreviated" href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a>
Change listserver email address & settings:
<a class="moz-txt-link-freetext" href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a>
List-Archive: <a class="moz-txt-link-freetext" href="http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html">http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html</a>
List rules & etiquette:
<a class="moz-txt-link-abbreviated" href="http://www.re-wrenches.org/etiquette.htm">www.re-wrenches.org/etiquette.htm</a>
Check out or update participant bios:
<a class="moz-txt-link-abbreviated" href="http://www.members.re-wrenches.org">www.members.re-wrenches.org</a>
</pre>
</blockquote>
<br>
<br /><br />
<hr style='border:none; color:#909090; background-color:#B0B0B0; height: 1px; width: 99%;' />
<table style='border-collapse:collapse;border:none;'>
<tr>
<td style='border:none;padding:0px 15px 0px 8px'>
<a href="https://www.avast.com/antivirus">
<img border=0 src="http://static.avast.com/emails/avast-mail-stamp.png" alt="Avast logo" />
</a>
</td>
<td>
<p style='color:#3d4d5a; font-family:"Calibri","Verdana","Arial","Helvetica"; font-size:12pt;'>
This email has been checked for viruses by Avast antivirus software.
<br><a href="https://www.avast.com/antivirus">www.avast.com</a>
</p>
</td>
</tr>
</table>
<br />
</body>
</html>