The KICKASS team have done it again! A new design in Voltage Sensitive Relays unlike anything currently on the market! This product is a unique dual-sensing VSR for charging an auxiliary battery system while ensuring that your vehicles starter battery is isolated when there is no charge from the alternator. Quick connect Anderson-style plugs allow for easy installation, no hard wiring! Side molded mounting points allow flexibility for installation whether it be under the bonnet or anywhere else in your 4WD, caravan or camper. The units are also water resistant and can even be used for marine applications The dual sensing function intelligently detects the charge of both the auxiliary and cranking batteries and allows for current to flow back in the case where the starting battery is low, or when an external charger is connected to the auxiliary battery such as AC or Solar The VSR is also fitted with an override switch for those sticky situations when you're cranking battery has been discharged and you need to transfer charge back from your auxiliary battery. The Basics on How It Works. When the vehicle's engine is running, the alternator will charge the start Battery. Once the start battery has reached 13.2V the VSR will connect the start and auxiliary batteries, enabling them to charge simultaneously When the vehicle's engine is not running, the alternator is no longer charging, so the start battery voltage will drop. Once the start battery voltage is below 12.8V, the VSR will disconnect from the auxiliary battery. This means the auxiliary battery can NOT drain the start battery Key Features: >Easy connection via input and output Anderson style plugs Charge your auxiliary battery without the risk of discharging Start Battery Protect electronics on auxiliary battery circuit from engine start up spikes Fully automatic operation Override Switch (Engages Relay regardless of sense voltage) Indication Light Wire (Active when VSR is engaged) Override Wire (Activated by + Positive Ignition Feed) Dual Sensing (Senses voltage of start and auxiliary batteries)