AGM battery questions

Frankly, regardless of the type of battery, you should resolve the overcharge condition. This is a VERY prevalent problem, and often fairly easy to correct. The main causes of overcharge are:

1...MOST of the time, voltage drop in the ignition harness. I've posted extensively on this problem. This, basically, is where the VR IGN terminal, which is the "sense" and power connection, is "seeing" less than "what the battery is." The VR "thinks" the battery is low and ramps up voltage

2....Sometimes, same problem as above in the ground circuit. The VR MUST be grounded TO the "same as" battery negative.

3...Fairly uncommon is a VR that is "out of spec" so far as voltage

4...Last is a battery that has been damaged, either a cell that is damaged, or sulphated because of undercharge or stored while undercharged