Need 8 volt batteries HELP!!!!

[Captain Ralph]

If you want to have a 32v system where batteries last, buy a smart charger. Quit screwing around with those old chargers and your batteries will live a long life.

Very much agreed.

BUT, people get over excited with this plan. Install level charge regulators on the charging alternators.
If you have cash to burn, you can do this for the very small duty cycle of a personal boat during operation. Balmar sells a great cash (and battery) burning regulator.
The battery draw is constantly changing when the boat is in use. A multi level charging alternator regulator is constantly restarting or never in float mode. It's best kept the batteries in absorb or bulk charge at these times as normal for a non-smart (stupid-stock) alternator regulator.
Every key of the radio, every flush re-starts the regulated alternator. Not good.
But just sitting at the dock, where most chargers eat batteries up, those smart chargers float down the batteries and keep them fresh. It's the later smart charger that keeps any bank up and fit between any wild weekends.