Question on power switch setting

[kelbylinn]

I have a 1981 42' GB trawler. In the main panel is the switch with three settings: Shore - Off - Generator. Question is when away from dock and running without Generator on, do I set the switch to "Off" and will that still allow the batteries to be charged from the main engines on that setting? When engines are running (twin 453 detroit diesels) at around 1300 + rpms, the voltage meter shows anywhere from 13.2 to 13.9 consistently with regular electrical load (no AC's of course). Help appreciated.

[Stu Jackson]

Charging from the main engines means you are charging from the alternators, which output DC.

The shorepower or generator means an AC source, i.e., EITHER the land based shorepower OR your generator) which then goes to a "shorepower" (sic) charger with AC input and DC output.

They are two completely separate methods of charging.

Since there is no AC input power when you have the generator off and are not at a dock, it doesn't matter what position that switch is in.

[kelbylinn]

Thanks Stu. That's the info I needed.

[smac999]

It is best to leave it off.

Because when you plug into shore it should be off when plugging in. And when starting gen it should be off. Both cases switched on after you have power. This way you won't forget. And it should be turned off again before unplugging from shore.

[Getweh]

Originally Posted by smac999

It is best to leave it off.

Because when you plug into shore it should be off when plugging in. And when starting gen it should be off. Both cases switched on after you have power. This way you won't forget. And it should be turned off again before unplugging from shore.

.... Or turning off genset