Its a 1998 29 ft fever with twin 454s. There is one battery on either side of the engine compartment. But why are there two battery swithes under the rear seat? The port side does everything and the starboard controls nothing that I can tell.

One switch for each engine wired to two seperate banks. However, battery bank 1 is usually port and bank 2 is starboard. With two switches you can cross the streams or charge both banks at once. Just remember not to move switch position with the engine running.

Would love to see a schematic of how our boats are wired...

I can't count how many times I have had that argument,after I tell them not to,most People say it's fine switch it while running.

Its OK only if you pass throught the BOTH position to switch batteries. But you should not pass through the OFF position because can safely run an alternator with no load BUT what you must not do is disconnect it from a load while it is running. That causes a voltage surge which can blow the diodes.

if it is a quality switch it should be a make-before-break design so technically you could safely go from 1->2->Both but it is a mechanical device and can fail or ill fated error when switching. as said above, results in taking out the diodes in a heartbeat

Here is a like to the Perko diagrams if this is what Back4More is asking about or was their question referring to Fountains in particular:

http://www.perko.com/images/catalog/...(8500INS1).pdf

One switch usually contols one engine, other engine or both and other switch usually controls one engine, other engine, both, and "house power" ie, cabin power, pressurized water, etc. If I remember correctly the port battery is the one that supplies house power.

No comment.... Lol

Works nice if you want to add 2 more batteries for a killer sound system. Mine runs off 3 all the time and the 4th one just sits there in case i spend the other 3. Then it will start the Star motor , thus charging the other batteries to start the other motor.

one switch per motor. what ever setting you puit it on is what that motor, drive and tab will work off of. or charge. normally your house systems is tied to the port motor, so what ever battery you point the port motor at, the house systems, will be using that battery.