Our 250-amp dual battery controller includes a three position switch to control the second battery through the operation of the solenoid. Switch position one isolates the auxiliary battery and shows no indicator light. Position two connects the auxiliary battery while the ignition is on and shows a green light. Position three connects the auxiliary battery at all times and shows a red light. Kit includes solenoid, toggle switch, pre-terminated wire/connectors, fuse holder, fuse and mounting hardware.