Battery ???

[dduflo]

I have 3 batterys on my '05 Islander. Fridge has been on for a couple of days and Port engine would not start. Starboad fired right up. Following the directions on the battery switch door I turned turned them to BOTH and still nothing. These were wired by the dealer and although I have changed batteries the wiring is the same. What do I look for or maybe there is a wiring diagram on the net you could referr me to. Thanks

 

[seabob4]

Switching to both on both switches should have started your port motor. Time to get the meter out and see what's going on. You also may have a loose connection on the port motor batt cable on the "common" post of the batt switch. I'd pull the switches down and make sure everything is tight...

 

[SCAdventure]

I thought that with the battery switch on both you would get an average of the two batteries. Half the current from the good one would go to the starter and half would go to charge the dead battery. Maybe you need to start with one on then run it with both.

 

[seasick]

I thought that with the battery switch on both you would get an average of the two batteries. Half the current from the good one would go to the starter and half would go to charge the dead battery. Maybe you need to start with one on then run it with both.

That's true as long as one battery is more charged (higher voltage) than the other. It's also true that switching to BOTH when one battery is fully charged and one is run down will offer less starting current to the motor.
If however there is a bad ground either between the two batteries or the second battery and the motor, using BOTH may not make any difference.

The BOTH position can help when both batteries are somewhat run down and neither has enough current capacity to start the motor but together they do.

In any case, staring on 1 and switching to BOTH ( never passing OFF) will charge the second battery if the connections are good and if run long enough.