Then {HEAD ~ the driver} turns the power supply switch on to provide a constant current to {TAIL ~ the vehicle battery} 
Then { HEAD ~ the driver } turns the power supply switch on to provide a constant current to { TAIL ~ the vehicle battery }
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL