Sea-Dog Smart Dual Battery Isolator [422790-1]Smart Dual Battery Isolator This Smart Dual Battery Isolator is ideal for dual battery applications. Allows two batteries to automatically charge at the same time and then isolates the batteries, ensuring the starting battery is always charged and ready for use. Automatically engages or disengages the circuit at pre set voltages by sensing the input voltage generated, eliminating the possibility of discharging the primary starting battery. Cut in