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