Throttle Fever, have you considered using a battery relay(combiner) on each side? You'd still charge both batteries by the motor as you currently do, but it would isolate the 2 batteries from each other to allow you to have a starting battery and a house battery for each motor.[/QUOTE]

Did consider that,(and is the right way to go) but it was alot easier in my applications to just go with using the switch (I like to believe the simple is better thing, Just Me). My wife and I are very good at remembering to change the switch. we do alot of tieing up with the stereo going thing. Pete

On my battery switches it actually is labeled "start only" under the both position.

Should you need to use the both position to start motors, is it ok once they are running to switch back (with motors still running) to normal 1 and 2 positions ?

Yes, you can switch while running, (make-before-break).....
as long as you don't pass thu the 'OFF' position. It is possible to fry the diodes in your Alt. doing so.

There is a warning in the Merc 500 EFI shop manual regarding running dual engine boats with the battery switch in "both" position (ie, both engine's batteries trying to be charged by both alternators). Manual says it can do permanent damage to the engine package and ECM.

What about a triple engine boat with a gen?!

Good question.. ;-) I must say this is not well enough pointed out this battery switch thing in these boats.... I have never really understood it. But the wiring diagram helped me understand. So thank you for posting it.

I have always put both switches on both and left them there the whole season. Never a problem. It is great to have the power on since I have a dual remote start on the boat.

But I have a problem.... When I start both engines, and switch one of the switches to 1 and the other to two, the engines still runs, but if I press the powertrim button, one engine stops instantly. HOW is this possible??? My impression is that the battery is dead and the use of the powertrim drops the voltage so low that the engine can't run. If I usually run on both, both batteries will be charged. Then why is that battery dead?

Also, the voltmeters must be wired from each engines wire harness to display the actual voltage on each engine? This is somewhat confusing as one can imagine the voltmeter shows the voltage of the battery on the respective side of the boat.

Thanx!

Can someone tell me how a 47 with triples are wired? There is 3 switches with 1, 2, off, and 1+2........... There are three batteries!! Then each switch can't take power from one or all three batteries when there is only the 1, 2, off and 1+2 options. To follow the wires is useless since they are routed through the bulkhead and cannot be followed all the way.

The generator have its own battery and switch. To make the confusion complete, this switch is the same as mentioned above, although there is only one battery... I assume the power for the generator is a completely separate system, and that the power the generator pumps out goes directly to the AC panel which in its turn run the triple charger, charging all three batteries simultaneously?

A buddy had a 442 Baja with trip 575's and a gen. 4 batteries, 4 switches. chit load of battery cables. He ended up with 2 dead batteries 1 day and none of us could figure how to swtich them to get the dead motors started. Found it easiest to just use my jump pack to the battery for each dead motor.

I have three switches under the seat for the motors. They also have "both" on them. The Gen has it's own system. Which as you stated I assume it goes to the panel/battery charger and will start all three motors. I did it last week to get the boat started. Had to wait about ten minutes and then they all fired up.

Your generator has its own battery for starting? I like the idea of the generator charging the batteries to start the motors, but I don't see how I could start the gennny if the batteries are dead.

I have two switches, two batteries and a generator. I was a little confused when I got the boat as to why it had two switches. I run both switches on "both". Now I'm getting a little concerned. I've owned other twin engine Bajas that only have one switch.