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A) With a 13th battery and only one string, if there were a failure in one of the cells, the system would most likely demonstrate the failure rather quickly and allow for the faulty battery to be removed while still maintaining adequate voltage to operate the 24V system. <br><br> B) On the other hand, Tom presents the exact reason behind the idea of the 3 - string design.<br><br>This is an off grid system.<br><br>I know this may open up a can of (philosophically varied) worms. But, this is the reasoning behind the two designs.<br><br>PS. Buss bars (if 3 strings) and 4/0 CU would be used. <br><br><br><br><font style="" color="#76923c">Wayne Irwin</font><font style="" color="#76923c">, EE<br>Director of Engineering<br></font><font style="" color="#76923c">
Pure Energy Solar International Inc. </font><font style="" color="#76923c"><br></font><font style="" color="#76923c"></font><font style="" color="#76923c">State Licensed Solar Contractor</font><font style="" color="#76923c"><br></font><font style="" color="#76923c">
License # CVC56695 </font><br>
<a href="mailto:PureEnergySolar@hotmail.com">Wayne@PureEnergySolar.com</a>
<br>
<a href="http://pureenergysolar.net/" target="_blank">http://pureenergysolar.com</a>
<br>
<font style="" color="#76923c">352 377-6527 Office</font><font style="" color="#76923c"><br></font><font style="" color="#76923c">352 336-3299
Fax</font><font style="" color="#76923c"><br></font><font style="" color="#76923c">352 316-1637 Cell</font><br><p class="ecxecxecxEC_EC_EC_EC_EC_MsoNormal"><font style="" color="#76923c"><span style="font-size:10pt;font-family:'Arial','sans-serif'">The
content of this message is Pure Energy Solar Confidential. If you are
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recipient and have received this message in error, any use or
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prohibited. Please notify me immediately by reply e-mail and delete this
message from your computer system. Thank you.</span></font></p><br><br><br><br><hr id="stopSpelling">From: tom@wagonmaker.com<br>To: re-wrenches@lists.re-wrenches.org<br>Date: Tue, 31 May 2011 13:36:16 -1000<br>Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison<br><br>
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<div>From a reliability standpoint I would never want to bet the farm on one
string. All it takes is the failure of one cell and the system is useless
until it is replaced. Three strings means a cell failure only reduces
capacity by 33% not 100%. I’ve always thought in off-grid systems it is a
good idea to build in as much redundancy as possible whenever possible.
Oh, and always use a buss bar system with multiple strings, it makes for a far
more stable system with less stress on the batteries.</div>
<div> </div>
<div>Tom</div>
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<div style="font-color:black"><b>From:</b> <a title="wayne@pureenergysolar.com" href="mailto:wayne@pureenergysolar.com">Wayne Irwin</a> </div>
<div><b>Sent:</b> Tuesday, May 31, 2011 11:49 AM</div>
<div><b>To:</b> <a title="re-wrenches@lists.re-wrenches.org" href="mailto:re-wrenches@lists.re-wrenches.org">Wrenches</a> </div>
<div><b>Subject:</b> [RE-wrenches] 24 volt Battery Bank
comparison</div></div></div>
<div> </div></div>
<div style="font-style:normal;display:inline;font-family:'Calibri';color:#000000;font-size:small;font-weight:normal;text-decoration:none">Hello
Esteemed Battery Gurus,<br><br>Which of the following do you believe is the
better 24 V battery bank?<br><br>A) 13 - Rolls 2-YS-31 2430 AH @ 20 HR (one
string) <br><br>or <br><br>B) 9 - Rolls 8-CS-25P 820 AH @ 20 HR (3 strings
of 3)<br><br>Thank you in advance for your input!<br><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"></font><font color="#76923c">State Licensed Solar Contractor</font><font color="#76923c"><br></font><font color="#76923c">License # CVC56695 </font><br><a href="mailto:PureEnergySolar@hotmail.com">mailto:PureEnergySolar@hotmail.com</a>
<br><a href="http://pureenergysolar.net/" target="_blank">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><br>
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