battery switch

[firemanfitz]

I have a boat with dual batteries and a perko battery switch. The previous owner had each positive wire from each battery going to the 1 & 2 post in the switch, but he has the positive engine wire going to starting battery post. Shouldn't the wire coming from the engine go to the common post in the battery switch. He also has each negative battery jumping to one another without a separate common ground. Is this right?

 

[H20Rat]

Depends on what you are trying to achieve. You didn't mention what type of boat or what YOU are trying to achieve, so here is where that wiring could be useful. Its on a boat with a big alternator, and he has a trolling motor. During normal engine running, he flips the selector to batt 2 and charges the trolling motor with the engine. Once stopped and the trolling motor is running, flip the selector to batt one so the trolling motor doesn't pull down the main batt.

As far as the ground, I actually prefer doing it that way vs a common engine block ground. I like keeping the total length of all ground cables added together as short as possible, and go overkill on the ground cable size.

 

[firemanfitz]

I have a seaswirl striper with a evinrude 135 ficht. I was told by a mechanic that the motor should be hooked up to my common battery switch not to the battery. I blew my emm and just wasn't sure if that could of cause the emm to fail. I don't think so. Your saying that it doesn't matter and it just depends how I want it to be setup. Also isn't it bad to switch batteries when the motor is running. Can't that bloe the emm

 

[bruceb58]

The engine should be connected to the common post. Switching the Perko switch is fine as long as you don't switch to the Off position while the engine is running.