Charge!

I’m in the midst of a project to replace the alternator at the moment.  The existing Hitachi alternator will generate up to 80A and is unregulated.  Being unregulated means the charging is less efficient and the house batteries can become over charged when motoring for long periods.

The new alternator is manufactured by Balmar and has an external regulator to control the charge rate and prevent over-charging.  The regulator senses the current draw and charges the battery in stages, offering less and less current as the battery gets close to being fully charged.  It’s like closing a door:  initially you can move the door quickly, but as it gets close to being fully closed it is best to slow down so the door doesn’t slam shut and cause damage.

The higher current will also make it easier to keep the batteries charged.  The result will be prolonged battery life and fewer engine hours.  Balmar sells even higher amperage alternators that would probably fit, but more powerful alternators create more drag on the drive belt.  100A is considered the limit without adding a second belt, which would require a change of pulleys on both the engine and the alternators.

I’d be tempted to make that change and switch to an alternator that supplies 120A, 150A or more, but the boat and it’s wiring are designed for the alternator that it has, so I’m reluctant to push things too far.

Installing the new alternator shouldn’t be too tough.  It’s designed with the same mechanical footprint.   The new external regulator will be harder.  There are new wires to be run that will be challenging.  The regulator needs to be installed close to the alternator and will be mounted above the engine in the engine room. Then there are two wires that run to the battery to sense voltage and temperature.  They’ll require pulling floorboards and threading wires behind panels.  By hook or by crook, we’ll get it done though and Quijote will be much happier for her new hardware.