Volt Sensitive Relay
 
Voltage sensitive relay for a 12 volt engine starter battery and domestic battery bank. The relay measures the starter battery voltage and at 13.3 volts (fully charged) opens it contacts to divert the charging voltage from the starter battery to the domestic battery bank. Should the starter battery voltage drop below 12.8 volts the relay will close its contacts to allow the starter battery to be recharged ahead of the domestic battery bank.
 
Optional for all heat exchanger engines.