The battery isolator is very similiar to the battery switch in that it can charge two batteries
and yet isolate the two.The difference being that there is no manual switch to operate using the battery
isolator, its all automatic. There is pros and cons to both setups, with the battery isolator you have
only one battery for the engine and one auxiliary battery for normally cabin use. Both batteries are
charged by the engine and when one battery is discharged it will not drain the other. An isolator is
basically a diode, a one way path through a circuit. There are different setups as with the battery
switch such as dual engine installations and isolators that will charge more than two batteries. The
battery switch can be manually switched between batteries to charge or start off from one or both
batteries, where the isolator cannot.
This is the most common setup for a single engine dual battery boat. The way that the isolator is installed
would be to disconnect the large charging wire from the alterntor, normally orange or red in color. This
wire would normally attach on the other end at the starter where it would find its way back to the battery
via the battery cable for charging. This wire would be capped off and taped back into the harness. Now a
new wire (red or orange) of the same gauge, normally about an 8 gauge would be attached to the alternator
and routed to the common on the isolator. Then the two remaining posts on the isolator are attached with
the same gauge wire and routed to each positive end of the batteries. Route all wires out of the way of
belts, and tie off the best as possible. This is all that is needed for installation. Now one battery can
be attached to the motor as normal, ground at block and positive at the starter. The other battery(normally
deep cycle) will need to be grounded at the engine and the positive ran to the cabin fuse/breaker panel
for lighting or other 12v use.
Note: Blue Water Marine is not liable for damages caused by improper installations or
repairs. The information on these pages are for "information only", not to replace manufacturers
instructions. These pages are meant for helpful knowledge for the do-it-yourself, if you are not
confident in what you are doing please leave the work for the experienced.
As with battery switches there are several different manufacturers of isolators available. A battery
isolator can be seen or purchased here.
Blue Water Marine 8690 S. Oceana Drive, Montague Mi. 49437