Does it really matter on my new to us, 16 foot Double Eagle whether I keep the 3 pole battery power switch already wired for a house battery, or buy a 4 pole battery switch? The boat is simple with a 60 hp Mercury auto lift/trim, running lights, fish finder, and bilge pump. There is a 12 volt starter, and a Trojan 12 volt AGM house battery from a boat we are selling. - Dirk
The difference between an off-1-2-both (3 pole) and off-on-combine (4 pole) comes down to separation of house and engine loads. The off-1-2-both switch has only one common post that runs all your circuits (house and engine) and you basically choose which battery 1 or 2, that will run this common post. The off-on-combine switch allows you to have dedicated engine circuits to engine battery and house circuits to house loads. Either switch works, depends what you want to do. Either switch, allows the option of having all batteries connected to all circuits.