Battery Overvoltage?

[okiepilgrim]

Tested the batteries Sunday night after being on the lake all day and the engine/crank battery read 12.9 Volts. Let it "rest" till morning and read it again. Same thing, 12.89 Volts. House battery read 12.58.
Do I need to be concerned with an "overvoltage"? I've read this can damage the battery. I can run the blower for a bit to drain off the excess, but curious about this. Also, this is a brand new battery (standard flooded deep-cycle Marine).

Would this indicate a potential problem with the alternator or isolator or something else?

Thanks as always.

[chpthril]

Those battery numbers are perfect. If you do suspect an over charging issue, you will want to measure the voltage with the engine running.