[Uhehner]

Looks to me like you have a bad meter. You cannot get anyway near 16 volts from a lead acid battery with the engine and battery charger off. Check your meter on your car battery. It should read about 13.8v with the engine running and 12 something with it off. We can go on from here if the meter checks. And remember the old saying "if it works, don't fix it". What concerns me is the wet battery and gel battery combination. That is usually a no-no. How does your battery charger know what it is charging and how much voltage to put out? Same goes for the regulators on your alternators. One more thought, do you have the battery selector switches in BOTH? That will really confuse the issue. Capt. George