[RE-wrenches] Imbalance In Multiple String Charging Current

[Dana]

What do specific gravity and load, rest and charge VPC tests
say? 

 

The VPC tests will usually pinpoint a weak cell. 

Higher VPC reading under a high state of charge and lower
VPC under a big load, normally done with the array &
generator turned off to maximize the effect. 

 

Typically the specific gravity reading will confirm this VPC
test cell readings and the SG will be lower for that cell
too.

 

Thanks,  Dana Orzel

 

Great Solar Works, Inc

E - dana at solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

 

"Responsible Technologies for Responsible People since 1988"

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf
Of Mark Frye
Sent: Thursday, July 22, 2010 11:30 AM
To: 'RE-wrenches'
Subject: [RE-wrenches] Imbalance In Multiple String Charging
Current

 

Folks, 

I have three strings of batteries cabled in parallel to a
common buss bar. 

During charging, one string takes significantly less current
than the others. 

What can I infer from this? Is the low current string
healthier, presenting higher impedance due to a higher state
of charge? Or is there a single bad cell with high impedance
in this string? Both, neither, something else, or can't know
without further information?

  
Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 
(530) 401-8024 
 <http://www.berkeleysolar.com> www.berkeleysolar.com  

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