Switch permits selection between either of two batteries, operation of both batteries in parallel, or complete disconnect of both batterie Alternator field disconnect. Interrupts alternator field when switch is turned to “off”. Allows switching to any position including “off” whether engine is running or not, without damage to alternator or electronic equipment. Rated at 230 amps continuous, 345 amps momentary. 2100 battery selector switch–with alternator disconnect.