Battery Equalization

Here is an old post by Bobby on the original process of equalization of AGM batteries. This will be updated by Bobby.

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copy of post from 2001

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AGM Battery Equalization Procedure:
By Bobby W.
Vessel Gra’inne
Size IP350
Date 2001

I 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 plate sulfation.

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 equalized.

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PS:
Since Bobby taught me this back in 2001, I have done this to my AGM back several times, and usually 2 times a season. I follow this, except I do the entire bank of 5 GP31 AGMs at once. I apply 15.5 VDC to a fully charged back for about 3-5 hours. I monitor the temperature and make sure all systems are off as to do no damage with the higher voltages.

Bobby:
Do you have any new procedures to this?
Thanks

Hayden

Bobby:
Do you have a more updated procedure for equalization? If so, can you post it in here? I simply turn get the bank full and in float mode, then turn off all items and reconfig the charger for lead acid bank. Then I set the charger to an equalization voltage of 15.5v and turn it on. The bank will take very little amps, 1-2, and the voltage will be held at 15.5v. I do this for 2-3 hours or longer if I can. This is how you taught me.

Do I need to do anything else? Thank you.

Hayden

Again, i just equalized my AGM Deka 6 GP31, 105 Amp Hr each battery bank and it is like new once again. This equalization process is easy.
1. Fully charge your bank.
2. Turn off all loads, lights, refrig, etc.
3. Configure your charger to put out 15.5 volts
( note: this may requir you to configure your charger to think its connected to flooded cells or gels as some will not equalize AGMs)
4. Start the process, monitor the bank temps, voltage and amps.
5. Stop after 3-4 hours
6. Reconfig your charger back to normal.

Note: some solar controllers and newer regulators have equalization built in. Read your manuals. It should be done once or twice a year!

Hayden

Also....as noted by Lifeline, in their manual, you can "condition" your batteries. Here is their writing:

Conditioning/Equalizing Charge: 15.5 volts for 8 hours
Conditioning/equalizing should only be done when the battery is showing symptoms of capacity loss. If conditioning/equalizing is necessary, first go through the normal charge cycle. Once the battery is as fully charged as possible, start the conditioning/equalizing charge.

See Lifeline here:
www.lifelinebatteries.com/manual.php

Hayden