Group 32 Duracell AGM Batteries at 14 Volts

[thompsdw]

I don't have shore power, so I have a little different setup. I am using solar chargers to charge 2 house batteries listed in the title. They routinely float at 14 volts. Is that a problem, or not? I'm a little worried that they are overcharged. Any help in appreciated.

 

[wayne0]

14 volts is pretty much the norm. The alternator charges at 14 volts in a healthy system.

 

[paulswagelock]

14 volts is a bit too high to float charge an agm battery, especially in hot weather. This is why I steer people away from them. Many older battery chargers and most all alternators put out too high of a voltage to maintain agm batteries and are not temperature compensated. Mostly, it can result in diminished life expectancy, which is one of the benefits for buying them.

As with all gelled and sealed units, AGM batteries are sensitive to overcharging. These batteries can be charged to 2.40V/cell (and higher) without problem; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages). Automotive charging systems for flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell), and a direct replacement with a sealed unit could spell trouble.