currently have a house battery bank consisting of 3 Gp-31 and 2 Gp
27’s which provide a calculated battery capacity of approximately
505 amp hours. Part of normal maintenance for the AGM batteries is a
process called equalization, which is performed to reduce internal
Details provided by Lifeline indicate that the equalization
process involves "charging" the battery at 15.5 VDC for a
3 hour period. During this process the current acceptance of the
battery will slowly drop from 3 – 5 amps to slightly more than .5
amps during the 3 hour equalization period. I’m sure that there
are other methods for doing the equalization that are probably
acceptable – if in doubt contact Lifeline. The key to the
equalization though is maintaining the equalization voltage at
15.5VDC for 3 hours.
Note: The following procedure was utilized because my power
supply was not capable of providing a stable regulated source of
15.5VDC at more than 3 amps. Even with the batteries fully charged,
each of the GP 27/31 batteries may draw 3 – 5 amps when the
equalization process is initiated. So in my case, with 5 individual
batteries in the house bank, initial equalization current could
easily have exceeded 20 amps.
The first step in this process is to fully charge the batteries
using the shore power charger. I normally leave the charger running
long enough to maintain the float charge for at least 4 hours before
I start the equalization.
I use a regulated DC power supply with an accurate DC Voltmeter
and begin the equalization process by setting the open circuit
voltage on the power supply to 15.5VDC and then connecting the power
leads directly to the terminals on each battery individually
(positive lead from battery under equalization is disconnected from
the remaining batteries in the house bank during equalization) – Careful
with the disconnected cable end, don’t want a short on this puppy!.
My power supply is current limited so that it will not provide
more than 3 amps DC. When I initially connect the power supply to
the battery being equalized the voltage drops considerably while the
current holds steady at 3 amps and then begins to drop off (allowing
the voltage to rise back to 15.5VDC) As soon as the voltmeter
indicates 15.5 VDC on the power supply I start the 3 hour
equalization process. I have to adjust the power supply occasionally
to maintain the voltage at 15.5VDC.
The process is repeated on each battery in the battery bank in
turn until all of the batteries have been