The present disclosure provides a method, apparatus, and system to switch
between direct current (DC) and alternating current (AC) power sources
for appliances with a third position to allow on-board recharging of the
DC power source. The method involves locking out a power source when the
other power source is powering the appliance and locking out both power
sources from operating the appliance when the appliance is being
recharged. The DC power source can remain coupled to the appliance during
operation and during recharging without necessitating removal for remote
recharging by the use of a unique switch.