Mark, If you had one "healthy" string connected in parallel with two "weak" strings, the tendency would be for the weaker strings to pull the stronger string down to their level. It's more likely an impedance issue in the string with the lower current. All other things being equal, look for bad connections in the low-current string. "Bad" in this case could be due to corrosion, one or more poor crimps, one or more bad cells, and so forth.
Your best friend here is your DVM. Apply a charge current to the entire battery and look for a point in the low-I string with a higher-than-normal voltage drop, especially when compared with the other two strings. It could also be a cumulative loss, such as several "sort of ok" connections, but each of which may have [say] a few fractions of a volt more drop across them than their counterparts in the other strings. It takes only a few millivolts difference to reduce the current through a battery to something much less than would otherwise be flowing. Dan --- On Thu, 7/22/10, Mark Frye <[email protected]> wrote: From: Mark Frye <[email protected]> Subject: Re: [RE-wrenches] Imbalance In Multiple String Charging Current To: "'RE-wrenches'" <[email protected]> Date: Thursday, July 22, 2010, 4:16 PM Imbalance In Multiple String Charging Current _filtered #yiv331797500 { font-family:Calibri;} _filtered #yiv331797500 { font-family:Tahoma;} _filtered #yiv331797500 { font-family:Century Gothic;} _filtered #yiv331797500 {margin:1.0in 1.0in 1.0in 1.0in;} #yiv331797500 P.yiv331797500MsoNormal { MARGIN:0in 0in 0pt;FONT-FAMILY:"serif";FONT-SIZE:12pt;} #yiv331797500 LI.yiv331797500MsoNormal { MARGIN:0in 0in 0pt;FONT-FAMILY:"serif";FONT-SIZE:12pt;} #yiv331797500 DIV.yiv331797500MsoNormal { MARGIN:0in 0in 0pt;FONT-FAMILY:"serif";FONT-SIZE:12pt;} #yiv331797500 A:link { COLOR:blue;TEXT-DECORATION:underline;} #yiv331797500 SPAN.yiv331797500MsoHyperlink { COLOR:blue;TEXT-DECORATION:underline;} #yiv331797500 A:visited { COLOR:purple;TEXT-DECORATION:underline;} #yiv331797500 SPAN.yiv331797500MsoHyperlinkFollowed { COLOR:purple;TEXT-DECORATION:underline;} #yiv331797500 P { FONT-FAMILY:"serif";MARGIN-LEFT:0in;FONT-SIZE:12pt;MARGIN-RIGHT:0in;} #yiv331797500 SPAN.yiv331797500EmailStyle18 { FONT-STYLE:normal;FONT-FAMILY:"sans-serif";COLOR:windowtext;FONT-WEIGHT:normal;TEXT-DECORATION:none;} #yiv331797500 .yiv331797500MsoChpDefault { FONT-SIZE:10pt;} #yiv331797500 DIV.yiv331797500WordSection1 { } OK, So no takers for the low current string being in a healthier, higher state of charge! Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com
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