Re: Dual battery setup

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Posted by Ken Denman ( on September 20, 2005 at 07:16:17:

In Reply to: Dual battery setup posted by Bob on September 20, 2005 at 06:52:18:

A battery isolator will let you completely discharge one battery without discharging the other one.

There are 2 main types of battery isolators. The diode based type and the relay (solenoid) type.

The diode type of isolator is basically two very high current diodes in a heat sink. The diode based isolator has the advantage of long life and trouble free operation but many of the diode based isolators cause a .4 to .6 volt loss which means that the batteries will not charge to as high a voltage as when they are connected directly to the boat's charging system.

The solenoid type of isolator uses large high current relays to control the flow of current. The main disadvantage is that the reliability isn't quite as good as the diode based isolator.

My money's on the diode-type because it'll stand up to the marine environment longer. The unit will have a wiring diagram in the package.

Keep cable runs as short as possible to prevent current loss.

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