[RE-wrenches] Imbalance In Multiple String Charging Current

[Exeltech]

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 <markf at berkeleysolar.com> wrote:

From: Mark Frye <markf at berkeleysolar.com>
Subject: Re: [RE-wrenches] Imbalance In Multiple String Charging Current
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Date: Thursday, July 22, 2010, 4:16 PM

Imbalance In Multiple String Charging Current

 
 
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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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