[RE-wrenches] Deka AGM (was Small battery bank vs too large array:

[Gary Willett]

Larry:

Are the problems you have encountered with the Deka/MK 12V AGMs also an 
issue with the 8AGC2 6V AGM? Are the problems you're seeing with climate 
controlled batteries, or with outside cabinet mounted batteries?

I have an application having I believe heat related failures with one 
48V string of outside cabinet 8AGC2 batteries in an off-grid battery 
based inverter/charger with generator charging (6kw LP generator). 
Temperature compensated bulk charging of 60A DC is delivered to the bank 
(0.3 x C20).

Gary


On 8/3/2012 5:03 PM, Larry Crutcher, Starlight Solar Power Systems wrote:
> Vince,
>
> I know of no such "vulnerability". In fact, an AGM can provide much 
> more instant current than any flooded battery. Concorde (Lifeline, 
> SunXtender, etc.) and Fullriver AGM's are very robust designs. On the 
> other hand, Deka AGM's, specifically the 12 volt 8A8D, are not to be 
> trusted at all. We have stopped selling all Deka/MK AGM's due to very 
> high failure rate.
>
> One other point to consider, having 5 parallel strings of 12 volt 
> batteries is generally asking for short battery life, especially with 
> an AGM since you can not check the SG to be sure all are charged 
> fully. Cells do not charge at the same rate and having parallel paths 
> for current will leave some cells deficit charged. Having many 
> parallel strings exacerbate this issue. If you do upgrade the bank, 
> opt for lower voltage, higher capacity batteries.
>
> Larry Crutcher
> Starlight Solar Power Systems
> (928) 342-9103
> _
> _
>
> 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*
>
>
>
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