Vince,
Seconding Larry's advice. The Concorde 8A8D is rated 250 A/h at
the C/20 rate, so 5 strings is 1250 A/h. Use instead one string of
PVX-12150HTs, 1,200 A/h as 2V cells. The physical size matches an
L16, and they have dual terminals for each pole, so you can either
run dual 4/0 cables (assuming that you downsize the DC inverter
breaker to 125A for 500A total) or make short bussbars, as we did
recently. You can then easily double the capacity, as this retreat
center clearly needs.
Allan
Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic
Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
Positive Energy, Inc.
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com
On 8/3/2012 4:03 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.
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