<html><body><span style="font-family:Verdana; color:#000000; font-size:10pt;"><div>I had one whole pallet of "famous brand" that were charged backwards. </div>
<div>The positive post (as charged) WAS painted red, but the plastic case "+" and "-" markings were by the wrong posts.</div>
<div> </div>
<div>Before I realized the error, I installed 8 of these at a customer, going by the red painted post, not noticing the case marking swap. These failed within a month or two. They did allow us credit toward the next larger model of battery.</div>
<div> </div>
<div>It wasn't until a customer installed a pair himself and went by the errant case markings that I learned of the case marking error. It blew a fuse for him but he got lucky and the inverter survived.</div>
<div> </div>
<div>Mark</div>
<BLOCKQUOTE style="BORDER-LEFT: blue 2px solid; PADDING-LEFT: 8px; FONT-FAMILY: verdana; COLOR: black; MARGIN-LEFT: 8px; FONT-SIZE: 10pt" id=replyBlockquote webmail="1">
<DIV id=wmQuoteWrapper>-------- Original Message --------<BR>Subject: [RE-wrenches] weak voltage<BR>From: Mick Abraham <<a href="mailto:mick@abrahamsolar.com">mick@abrahamsolar.com</a>><BR>Date: Mon, October 15, 2012 9:24 am<BR>To: RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><BR><BR>Hello, Wrenchies~<BR><BR>Mac Lewis wrote about battery strangeness on the Sunny Island system for his clients. Here is a theory to consider, Mac.<BR><BR>I once bought a 48v string of >famous brand< two volt cells in which one cell had been loaded backwards into its case. When hooked up according to the +/- markings on the case, this cell was discharging at the same time the rest of the string was charging so even though the others were running high during the charge, the end to end voltage immediately slumped to relatively low values after the charge was ended. The one cell was effectively missing in action.<BR><BR>My client was a DIY type who was distant from my location but he owned a voltmeter that was still in the box. I coached him through a "voltage walk" up the string and sure enough we found the one increment that was subtracting from overall string voltage instead of adding to it. The >famous< battery supplier said this was impossible, they are checked three times, this never happens & can't happen, blah blah...and they were only convinced when the cell was back in their shop and they could measure this for themselves.<BR><BR>Even after they checked it, they said, "It's the first time in our 20 + years with that brand that we have ever seen this." Black swan.<BR><BR>At my request, the company paid to ship back the entire string and ship all new replacement cells to the client. This seemed important because the other 23 cells had been subjected to a high voltage per cell and had gotten a bit hot before the problem was discovered. <BR><BR>++++++++++++++++++++++++++++<BR><BR>Perhaps this theory is worth checking on site. Whatever you find to resolve this problem, Mac, be sure to report back on list so we can all learn. <BR><BR>Jolliness,<BR> <BR clear=all>Mick Abraham, Proprietor<BR><A href="http://www.abrahamsolar.com/" target=_blank>www.abrahamsolar.com</A><BR><BR>Voice: 970-731-4675<BR>
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