Dual Battery Isolators and Voltage Sensitive Relays

A dual battery isolator or Voltage Sensitive Relay (VSR) allows your auxiliary battery or batteries to be charged while your engine is running. It provides automatic isolation of the cranking and auxiliary battery when the engine is switched off preventing your cranking battery from being discharged by your 12v appliances such fridges and lighting. Some VSRs have a manual override to allow for jump starting if the cranking battery is accidentally discharged. If you plan on implementing this feature it is important to use adequately sized cables.