[RE-wrenches] Bulk Chrging Rate for AGM Batteries

Peter Parrish peter.parrish at calsolareng.com
Sun Feb 27 12:35:20 PST 2011


We have a portable "demo-off grid" system (24 Vdc, 120 Vac, 1kW-ac) and
occasionally we end the day with a fairly deep discharge 11.6-11.7 V (80%
DoD).

I like to get a deeply discharged battery back up to 100% capacity as soon
as possible (as opposed to letting the 850 W PV / charge controller system
charge it up over a several days) and I have a AC battery chargers with
"20A', "10A" and "2A" bulk settings along with being able to choose, "wet",
"gel" and "AGM" settings.

Our battery of choice is a SunXtender AGM battery (PVX-2120L, 12V 253 amp-hr
(C/120).

My question: Starting with this battery at say 11.6 volts (open circuit), is
it safe to begin the bulk charge at ~8% of its C/120 capacity (i.e. 20A),
and let the charger go into absorption at 14.4 V (with temperature
correction of course) and finish at 2A? How high could I safely start the
bulk charge? 

 
Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parrish at calsolareng.com  
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885

 




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