Battery strings [RE-wrenches]

[Chris Worcester]

Hi Ray,

There are (4) 4/0 going to the batteries from each buss; (2) to each series
string. The Cobra Flex is THW with a 360A rating in free air, which it is.
Looks like the (4) can carry 1440 amps to me. With the inverters rated at
3600 watts & low battery cut out set at 45.2 volts the amps draw is 79.6A
per inverter x 10 is 796A. This is how I did the math. How are others
setting up these large battery/inverter/charger systems? 

Sincerely,

Chris Worcester 
NABCEP Certified PV Installer
USA Distributor of Proven Wind Turbines
Toll Free: 877-682-4503
Fax: 530-582-4603
www.solarwindworks.com
chris at solarwindworks.com
"Proven Energy Solutions"
-----Original Message-----
From: Ray Walters [mailto:walters at taosnet.com] 
Sent: Tuesday, September 19, 2006 5:51 PM
To: RE-wrenches at topica.com
Subject: Re: Battery strings [RE-wrenches]


I agree with Hugh, that single strings are over rated and a single 
failure can be serious. However, I've definitely seen my share of 
problems from systems that over paralleled and didn't balance the 
cabling (pull from opposite corners) but I've seen fairly amazing life 
out of 4 parallel strings of golf cart batteries ( can you believe 10+ 
years) so its not bad. Also, I've seen large differences in battery SOC 
with systems with only a single series string.
I think if you really wanted to nail it, we would need battery 
monitoring and charging on each cell or small group of cells, that 
charges and maintains them independently. This is a reality in the 
Electrc Vehicle world and is necessary for newer battery chemistries 
like Lithium Ion.

Also Chris, when you said you had a pair of 4/o cables going to the 
batteries, wouldn't 10 Outback inverters combined exceed the ampacity of 
those 2 cables, or are there other considerations (such as out of phase 
current draws) I'm missing?

Ray Walters


- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & how to change your email address:
www.mrsharkey.com/wrenches/etiquette.php

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com


- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & how to change your email address: www.mrsharkey.com/wrenches/etiquette.php

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------