Battery Selector Switch - Non-Locking With Alternator Field Disconnect For use with two or more batteries and single or dual engine systems. Permits selection between batteries for starting and charging, or operation of both batteries in parallel. For use in systems under 50 volts. Rated for 250 amps continuous, 360 amps intermittent.For dual engines two switches are required. Alternator Field Disconnect. Alternator Field Disconnect will interrupt the field current (reducing the possibility of damage) if turned "OFF" with the engine running. PERKO #8503DP