I install (and use) a battery selector switch. Assuming your trolling motor batteries are separate from the cranking battery, a battery selector switch can be configured in a way as to cut off the cranking and any accessories (powerpoles, Talons, depth finders, etc) that are connected to it, or it can be used to select either the cranking battery, a trolling battery, or both incase you have a cranking battery failure. If Basscat is talking about the older Knife switches, do no use this in the bilge area of the boat. It could possibly spark and set off gasses accumulated in the bilge area.JohnJones Trolling Motor Services870 773 3474Motorguide/MinnKota/PowerPole/Lowrance/Humminbird