JayCorp Dual Battery Isolation Kit with 140A Smart Battery Isolator (VSR Voltage Sensitive Relay) Suitable for 12V Marine, Off-Road Vehicles, RV, 12V Auto & Solar Systems 140 Amp Voltage Sensitive Smart Relay for Battery Isolation. Priority Charging for Starting Battery. Safe for Alternator Outputs up to 120 Amps. Fully Automatic and can be installed anywhere with its 2.5" x 2.5" x 2" size. Water and dust resistant.