[RE-wrenches] Small battery bank vs too large array

Vince McClellan Vince at solarenergydesign.com
Fri Aug 3 14:01:10 PDT 2012


On 8/2/2012 1:06 PM, Drake wrote:
>
> Hello Wrenches,
>
> Thanks for your help with this question.
>
> I've had a breakthrough on the design of this system.  I talked with 
> Tom at Midnight Solar, and he explained that Concord batteries can be 
> charged at C X 5 if necessary, i.e., 5 X AH capacity of the bank. The 
> batteries like a fast charge.  They are a bit spendy, but will 
> simplify the overall system design.
>
> From the Manual:
> "The charging current during the Bulk stage should be set as high as 
> practical; higher current mean faster recharge time.  For repetitive 
> deep cycling, chargers should have an output current of at least 0.2C 
> (20 Amps for a 100 Ah battery).  If the output current is less than 
> this value, the cycle life of the battery may be negatively affected. 
> Due to low impedance design, Sun Xtender batteries can tolerate 
> in-rush current levels as high as 5C (500 A for a 100 Ah battery). "
>
> It is imperative to keep the system voltage at the required set 
> point.  The CC regulation will prevent the batteries from being 
> harmed, as the voltage will rise quickly.
>
> Drake
>
> Drake Chamberlin
> /Athens Electric LLC
> OH License 44810
> CO License 3773
> NABCEP Certified Solar PV Installer
> 740-448-7328
> /http://athens-electric.com/
>
>
>
>
>
> _______________________________________________
> List sponsored by Home Power magazine
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Options & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out participant bios:
> www.members.re-wrenches.org
>
Just a word of caution on the AGM batteries. AGM's do have some 
vulnerabilities compared to deep cycle wet filled batteries. We had a 
bank of 20, 8A8D running a Buddhist Retreat compound and were unable to 
convince our clients that there were limitations to the amount of power 
that they could run at one time. They managed to overheat and destroy 
the whole bank of batteries we think by using too much power during a 
retreat camp. People had brought there own appliances to use at the camp 
and we still don't know what the total load was on the 4, Outback VFX 
3648 inverters. I'm guessing it was up there close to the 14.4 kW limit 
of the Outback inverters. We also petitioned our client for a larger 
battery bank but they didn't think they would ever need that much power.

-- 

-- 

*Vince McClellan
Energy Design
_www.solarenergydesign.com <http://www.solarenergydesign.com/>_
p: 541.485.8122; f: 541.338.3168*
Energy Design Logo
This email and any files transmitted with it are confidential and 
intended solely for the use of the individual or entity to whom they are 
addressed. If you have received this email in error please notify the 
sender. If you are not the intended recipient you are notified that 
disclosing, copying, or distributing the contents of this email is 
strictly prohibited.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20120803/0e57773b/attachment-0003.html>


More information about the RE-wrenches mailing list