We have NAPA golf cart batteries, 5 years old, and not the best quality.

They are ready for replacment, but here in Norway Trojans cost twice as much as in the US or the UK, so we want to stretch another year from the batteries we have.

Winds are often absent here, so we motor a lot, which of course provides lots of charging.

Our Balmar MC 612 controller charges at 14.6 volts for a while and then tails off, using the standard deep cycle program, eventually reducing to charging at about 5 amps. If I switch the alternator off then on again, it fools it into doing another bulk charge cycle at 14.6 volts, running about 30 amp charge even if battery is pretty full. This gives us quite a bit longer on battery while anchored.

I am considering reprogramming the Balmar controller to charge at higher voltage (14.8 is max possible) Any comments?

I can boost bulk charge voltage, absorption voltage or both. What do you think?