12 volt dillemma

[gasdok007]

I'm trying to troubleshoot an electrical problem - aluminum hull, twin honda outboards, two batteries.Boat is out of water on trailer. Port battery keeps draining and dying.This is also the housekeeping battery,but with battery switches off there is no current draw.I'm thinking that the engine rigging may be wrong.The port ignition must be on in order to power the starboard ignition,and when the battery ground is connected to the motors (or either motor) ther is continuity between the + terminal and the metal hull( my test light goes out when I disconnect the negative to the motor).My understanding is that the negative ground should be isolated from the metal hull.Do the mounting brackets tie the ground to the hull or is something else wrong? Any thoughts appreciated.

[longliner45]

have you had the cells checked in the one battery ? even new ones can be bad

[Tim B]

Sounds like something is shorting the battery. A simple check is to disconnect one side of the battery and put an ammeter in the circuit (at the battery). If there is no current flowing at the battery, take it out and see if the same thing happens on the work-bench at home.

Tim B.

[gonzo]

The hull is connected to the negative ground. That is the correct setup. The test light is not showing continuity but voltage difference. That is correct too.

[solrac]

maybe cheapest solution, install a 2 pole-circuit breaker & isolate both positive + negative battery pins...

[gonzo]

If the battery is draining, you need to find the problem. It shouldn't happen if the system is installed correctly. What may appear to be a cheap and fast solution could create a worse more expensive to repair problem.