ProMariner 130A Single Alternator 2-Battery Isolator

The ProMariner 130A Single Alternator 2-Battery Isolator charges two banks from one alternator, with gold-plated terminals.

One alternator into two banks is the most common isolator arrangement on a boat, covering starting and house. It is also the configuration people most often try to improvise with a battery switch left on 'both', which works until the house loads flatten the starting battery overnight.

A hundred and thirty amps handles a substantial alternator, and the isolator rating should exceed the alternator's output rather than match it. An isolator running at its limit heats, and the resulting resistance costs charging voltage exactly when the system is working hardest.

Gold-plated terminals resist corrosion on connections that live in an engine space and carry real current. This is a conventional isolator rather than a zero-loss design, so some voltage drop applies across it. Explore more battery isolators and charging relays.

• One alternator into two banks, the common arrangement
• Leaving a switch on 'both' flattens the starter overnight
• The rating should exceed the alternator's output
• An isolator at its limit heats and costs voltage