Dual Battery Isolator Problem

[mquinton699]

Last year at some point I had to switch from using Battery 1 or 2 to using both batteries just to get any power. I replaced the switch but it didn't fix the problem. Last weekend I replaced the isolator and it fixed until I tried to start the engine. As soon as I tried to start the engine I heard a "pop" sound and now I'm right back where I started, using both batteries to get any power. The batteries are new. Please help.


Rinker 2006 270 EC

[cal40john]

Are the batteries getting charged? What are their voltages?
Have you checked all connections for corrosion?
Lots of other possibilities.

[more]

Originally Posted by mquinton699

Last year at some point I had to switch from using Battery 1 or 2 to using both batteries just to get any power. I replaced the switch but it didn't fix the problem. Last weekend I replaced the isolator and it fixed until I tried to start the engine. As soon as I tried to start the engine I heard a "pop" sound and now I'm right back where I started, using both batteries to get any power. The batteries are new. Please help.


Rinker 2006 270 EC

show picture. something with wire is wrong

[mquinton699]

It was working fine until the battery switch was turned off while the motor was running.

[cal40john]

Originally Posted by mquinton699

It was working fine until the battery switch was turned off while the motor was running.

Check for charging, doing that can blow the diodes in the alternator.

[mquinton699]

My voltage meter on the dash shows it is charging. The big question is why would it pop the isolator when I try to start it?

[Sailmonkey]

Can you provide a schematic of what is wired where? And what make of isolator you’ve got?

[waterman46]

You wrote in the first post "Last weekend I replaced the isolator and it fixed until I tried to start the engine.". What do you mean that it fixed? What tests did you do to determine everything was working right after replacing isolator?
As a minimum, please do the following tests:

Disconnect any shore power chargers, wait 30 minutes. Then measure battery voltage before starting engine, with the battery switch in OFF position. Once you get it started, then test voltage at alternator output terminal, and on each side of the isolator, and at each battery terminal with the switch in the Batt1, Batt2 and Both positions. For these tests, it is essential that you connect the black lead of the multimeter to the same place each time, preferably the alternator case or it's ground terminal.

Also please let us know what is the battery size, isolator type and model, and the alternator type (at least, is it a standard automotive size or something larger) and the voltage regulator type (external or internal to the alternator). Post results here, you will get better help.

BTW if you heard a pop, I would bet there is a bad connection or a short circuit somewhere.

[MV Caroline]

Do you have an ACR between the two banks? it could be wired incorrectly and the pop you are hearing is the ACR solenoid switching the batteries off instead of isolating the banks.