<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">While I think that any system with more than three parallel battery stings is a FUBAR waiting to happen, I agree with OC devices on all the strings and using the bussbar technique. I would certainly go with Class T fuses rather than CBs as the Class T is current-limiting and boy do we have current in a battery short!<div>cheers, bob-O</div><div><br><div><div>On Apr 20, 2011, at 11:16 AM, R Ray Walters wrote:</div><br class="Apple-interchange-newline"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Tom;<div><br></div><div>That's exactly what Daryl and I were suggesting: all strings paralleled to a central combiner box with breakers on each series string.</div><div>The only thing I left out was that each cable set should be the same length ( which Daryl was already suggesting).</div><div>You need to reread what we were talking about. We got this idea from you many years ago, so the record is not broken;</div><div>its been pirated, reposted for Free download on all sorts of unsavory sites, and you aren't getting a royalty check....</div><div>Imitation is the sincerest form of flattery, and this list listens to and appreciates you.</div><div><br></div><div>Thanks,</div><div><div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div>R. Walters</div><div><a href="mailto:ray@solarray.com">ray@solarray.com</a></div><div>Solar Engineer</div><div><br class="khtml-block-placeholder"></div><div><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span>
</div>
<br><div><div>On Apr 19, 2011, at 10:16 PM, Tom Elliot wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="WORD-WRAP: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space" dir="ltr">
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<div style="FONT-FAMILY: 'Arial'; COLOR: #000000; FONT-SIZE: 10pt">
<div>The broken record will now repeat himself yet again. Bussbars are the
way to go, not across battery terminals but individual strings connected to a
central positive and negative buss from which the inverter connection then
runs. This allows fusing of each individual connection and also allows for
smaller positive cables and no need to have identical length parallel cables
since each string is independently connected. It’s what telecom
installations use. The Telecom guys who showed me how to do it literally
laughed when told about paralleling across battery terminals. They then
told me they considered it profoundly stupid and dangerous and since I had just
avoided a meltdown myself by catching a bad cell before complete failure I got
the message pretty quick.</div>
<div> </div>
<div>Really guys, this is amazingly simple and yes, it may mean a bit more
cabling and another component but from a safety standpoint those considerations
are pretty minor and cheap insurance against disaster.</div>
<div> </div>
<div>Tom</div>
<div> </div>
<div> </div>
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<div> </div>
<div style="BACKGROUND: #f5f5f5">
<div style="font-color: black"><b>From:</b> <a title="ray@solarray.com" href="mailto:ray@solarray.com">R Ray Walters</a> </div>
<div><b>Sent:</b> Tuesday, April 19, 2011 6:01 PM</div>
<div><b>To:</b> <a 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] Batteries in parrallel
Failure</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">I
like the fused parallel idea; could save the system, and would make battery
troubleshooting nice.
<div>I would suggest #6 jumpers with 50 to 60 amp breakers, so the system
could be operated on just a few strings if needed.</div>
<div>
<div> </div>
<div><span style="widows: 2; text-transform: none; text-indent: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; border-collapse: separate; font: normal normal normal 12px/normal helvetica; white-space: normal; orphans: 2; letter-spacing: normal; word-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; " class="Apple-style-span">
<div>R. Walters</div>
<div><a href="mailto:ray@solarray.com">ray@solarray.com</a></div>
<div>Solar Engineer</div>
<div> </div>
<div> </div><br class="Apple-interchange-newline"></span></div>
<div> </div>
<div>
<div>On Apr 19, 2011, at 8:29 PM, Darryl Thayer wrote:</div><br class="Apple-interchange-newline">
<blockquote type="cite"><span style="WIDOWS: 2; TEXT-TRANSFORM: none; TEXT-INDENT: 0px; BORDER-COLLAPSE: separate; FONT: medium helvetica; WHITE-SPACE: normal; ORPHANS: 2; LETTER-SPACING: normal; WORD-SPACING: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px" class="Apple-style-span">
<div>
<div style="MARGIN: 0px; FONT-FAMILY: 'times new roman', 'new york', times, serif; FONT-SIZE: 12pt">
<div style="MARGIN: 0px; FONT-FAMILY: 'times new roman', 'new york', times, serif; FONT-SIZE: 12pt">
<div style="MARGIN: 0px">
<div style="MARGIN: 0px; FONT-FAMILY: 'times new roman', 'new york', times, serif; FONT-SIZE: 12pt">Batteries
in parallel, How to protect from catastrophic failure.</div>
<div style="MARGIN: 0px; FONT-FAMILY: 'times new roman', 'new york', times, serif; FONT-SIZE: 12pt">I
just got contacted to commission a solar system off grid not of my
design. Eight battery strings in parallel, AGM batteries, 24 volts
@ 120 AH each string (two 12 volt in series) New system, new batteries,
Silent POwer Inverter. Two kW DC array. generator to charge
through Silent power. (present installer is not sure how to do final set
up and testing) </div>
<div style="MARGIN: 0px; FONT-FAMILY: 'times new roman', 'new york', times, serif; FONT-SIZE: 12pt"> </div>
<div style="MARGIN: 0px; FONT-FAMILY: 'times new roman', 'new york', times, serif; FONT-SIZE: 12pt">I
am most concerned about 8 batteries in parallel, (especially since last week a
set of AGM burned up having 5 in parallel Owner had no way to break the
paralleling of the batteries, she could only stop the chargeing)
What I am proposing for your review is requireing the installtion of two
combiner boxes Midnight solar with a breaker in each battery string, using
about 3' of #10 to connect each battery string to the combiner box. This
way if a battery failed and the paralled strings were to "dump" into the
failed battery it would trip the breaker. I was thinking of using a 30
amp breaker in each string. The main breaker is set at 240 amps. </div>
<div style="MARGIN: 0px; FONT-FAMILY: 'times new roman', 'new york', times, serif; FONT-SIZE: 12pt"> </div>
<div style="MARGIN: 0px; FONT-FAMILY: 'times new roman', 'new york', times, serif; FONT-SIZE: 12pt">Ideas
Please? <span class="Apple-converted-space"> </span><br></div></div>
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