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Old 06-07-2011, 14:48   #1
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Location: Northern Chesapeake
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Charging Voltage on Mixed Banks

I installed a new Xantrex Truecharge 2 60 amp charger. It will not differentiate between 2 different types of batteries in each bank. You set it for either AGM, flooded, or gel for everything. The house bank consists of 6 6v wet cell batteries, set to 3 pairs for each set (12v), about 675 total amps. The starting battery is a single Optima AGM Blue Top.

The charger charges on the flooded setpoint: 12.4v absorption, 13.5v float, and 16.0v equalization.

The charger charges on the AGM setpoint: 14.3v on absorption, 13.4v on float, and no equalization.

1. If I set the charger for flooded mode, will I fry the Optima during equalization?
2. If I set the charger for AGM mode, will the flooded batteries never come up to full charge?
3. What is the purpose of equalization anyway?
4. Any/all suggestions are appreciated.
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Old 09-07-2011, 02:16   #2
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Location: St. Petersburg, FL
Boat: Gulfstar Long Range Trawler; 53'; BearBoat
Posts: 811
Re: Charging voltage on mixed banks

The voltages you included in your post did not look correct so I downloaded the TrueCharge2 Owner's Manual. My copy shows the following on page 2.5:

Flooded Lead Acid (FLA)
Absorption: 14.4VDC Float: 13.5VDC Equalization: 16.0VDC

Absorption: 14.3VDC Float: 13.4VDC Equalization: Not Applicable

Look to the Optima website for their specs to be sure, but that 0.1VDC difference should not matter. However, your charger has the capability to utilize temperature compensation to reduce the charging voltage as the temperature at the bank increases. This is a worthwhile accessory, especially when AGM batteries are being charged. Temperature compensation also works during cold weather by increasing the charging voltage, thus ensuring a complete charge.

Equalization is the deliberate and controlled raising of the the charging voltage with a relatively low charging current to break up sulfate deposits that form on the plates of a FLA battery. Sulfation is caused by any number of reasons included, but not limited to:
1. Insufficient recharge.
2. Long term storage in float mode.

Most AGM manufacturers do not "allow" equalization as high voltage is one of the quickest ways to kill an AGM battery. Again, check the Optima website for authoritative advice.

Hope this helps.
Charlie Johnson
JTB Marine Corporation
"The Devil is in the details and so is salvation."
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