Twin Engine Fountain owners
 

If you have two battery switches, where do you set them when boating. 1,2 and both on our switches. Where do you run yours just curious?

Both while running, then on one or two (depending on the battery type on those legs, starting or deep cycle), for anchoring and stereo use while floating. When on both they (both batteries) get charged. While floating you always have one good battery for starting, if you switch to one.

Torched both alternators running the boat on "Both." I run one motor on each battery and shut them down when I anchor. My stereo, for some reason, is wired to play regardless of switch position, so I generally keep an eye on my battery power for a day at the beach. Also...I carry a jump pack!

same...

Mine are eather on both or off, guess i never tried the stereo on one and start on the other! I have heard of some people having problems so they run on 1 and 2.

This has been brought up before. I forget who found it but Mercury doesn't recommend leaving them on "Both" when the motor is running. It has something to do with the possibility of different ground potential between the motors, which as sommerfliesby has pointed out can cause problems with your alternators or computers.

I leave mine on 1 and 2, the stereo as well as the cabin pulls off of the port motor battery, and I use a dual (start, deep cycle) style battery there.

Found this, I think US1 sent it to me.

Interesting, having some minor electical problems on our 38 Lightning, and was talking to Shogren, and Brian Forehand at Key West, and both said starbord on 1 and port on 2. Or, the way my switches are wired, both battery switch arrows pointing at each other.

Sorry for my misunderstanding. Both my boats have four batteries. My both is for both batteries on one side (or engine). Mine do not share batteries engine to engine. Two for one engine and two for the other. Although my F550 has two alternators on a two battery system without a switch, will look at that schematic and see how they are wired?

My port is set to 2, SB set to 1. (switches pointed away from each other, left switch points to the left, right to right) Keeps motors and batteries separate with no fear of getting caught with dead batteries or having the alts fight each other. No need to screw around with switching the switches every time you stop or go. Never a problem yet. K.I.S.S.

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.