[RE-wrenches] 24 volt Battery Bank comparison

[Tom Elliot]

Good on the buss bars Wayne.  Using them removes the concerns about multiple strings and increases redundancy and system stability.  You won’t need 4/0 between single strings and the buss bar, you can probably easily use smaller cable, just size it for the individual string.  4/0 to the inverter of course.

I echo the concern about the higher voltage bank though.  Most off-grid systems have some low voltage DC elements, or at least offer the opportunity to add them, so the higher voltage could be a problem, especially during equalization.  If you use the buss bars, keep system voltage high enough, and the batteries are well-cared for, it shouldn’t be necessary to add that one extra battery.

From: Wayne Irwin 
Sent: Tuesday, May 31, 2011 2:05 PM
To: Wrenches 
Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison

No DC loads at all. 

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 
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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From: bob-o at electronconnection.com
Date: Tue, 31 May 2011 16:59:43 -0700
To: re-wrenches at lists.re-wrenches.org
Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison

Wayne, 
I'd recommend against that. To do an effective equalization charge on that bank you'll need to get the voltage up to at least 2.6-2.7V per cell. That would mean a 13 cell pack voltage of 34-35V. Got any DC loads at all? Danger, Will Robinson, Danger!  Using the inverter as a charging source? I think you'll run out of transformer windings or at the very least reduce your amperage output greatly toward the end of that cycle.
Hopefully, Jamie can jump in with an opinion here as well.
Good Luck!
Bob-O 

On May 31, 2011, at 4:28 PM, Wayne Irwin wrote:


Just for a little extra.

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 
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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