Battery Charging 40 HP Evinrude

[mh10129869]

Rookie boat owner - dumb question.

There are 2 cables connected to the battery terminals. The main one is for starting the motor. The other, much smaller one, appears to be for lights, etc. There is a short somewhere and my lights stay on all the time, even when the key is turned off.

THE QUESTION: If I just disconnect the small cable the lights go off. Does that cable have anything to do with the alternator charging the battery?

[boats.net]

The large battery cables are for outboard and will charge battery as long as they are connected.