[RE-wrenches] 24 volt Battery Bank comparison

[James Surrette]

Hi Wayne, 

Why not 12 cells (24VDC) and put the 13th in storage as DRY? 

Regards, 

Jamie

>>> Wayne Irwin <wayne at pureenergysolar.com> 5/31/2011 9:01 PM >>>
 A) With a 13th battery and only one string, if there were a failure in
one of the cells, the system would most likely demonstrate the failure
rather quickly and allow for the faulty battery to be removed while
still maintaining adequate voltage to operate the 24V system.

 B) On the other hand, Tom presents the exact reason behind the idea of
the 3 - string design.

This is an off grid system.

I know this may open up a can of (philosophically varied) worms. But,
this is the reasoning behind the two designs.

PS. Buss bars (if 3 strings) and 4/0 CU would be used.



Wayne Irwin, EE
Director of Engineering
Pure Energy Solar International Inc. 
State Licensed Solar Contractor
License # CVC56695 
Wayne at PureEnergySolar.com ( mailto:PureEnergySolar at hotmail.com )
http://pureenergysolar.com ( http://pureenergysolar.net/ )
352 377-6527 Office
352 336-3299 Fax
352 316-1637 Cell

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From: tom at wagonmaker.com
To: re-wrenches at lists.re-wrenches.org
Date: Tue, 31 May 2011 13:36:16 -1000
Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison

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>From a reliability standpoint I would never want to bet the farm on one
string.  All it takes is the failure of one cell and the system is
useless until it is replaced.  Three strings means a cell failure only
reduces capacity by 33% not 100%.  I’ve always thought in off-grid
systems it is a good idea to build in as much redundancy as possible
whenever possible.  Oh, and always use a buss bar system with multiple
strings, it makes for a far more stable system with less stress on the
batteries. 

  

Tom 

  

  

  

From: Wayne Irwin ( mailto:wayne at pureenergysolar.com ) 

Sent: Tuesday, May 31, 2011 11:49 AM 

To: Wrenches ( mailto:re-wrenches at lists.re-wrenches.org ) 

Subject: [RE-wrenches] 24 volt Battery Bank comparison 

  

Hello Esteemed Battery Gurus,

Which of the following do you believe is the better 24 V battery bank?

A) 13 - Rolls 2-YS-31 2430 AH @ 20 HR (one string)

or

B) 9 -  Rolls 8-CS-25P 820 AH @ 20 HR (3 strings of 3)

Thank you in advance for your input!


Wayne Irwin, EE
Director of Engineering
Pure Energy Solar International Inc. 
State Licensed Solar Contractor
License # CVC56695 
mailto:PureEnergySolar at hotmail.com
http://pureenergysolar.com ( http://pureenergysolar.net/ )
352 377-6527 Office
352 336-3299 Fax
352 316-1637 Cell

The content of this message is Pure Energy Solar Confidential. If you
are not the intended recipient and have received this message in error,
any use or distribution is prohibited. Please notify me immediately by
reply e-mail and delete this message from your computer system. Thank
you. 



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