The motor is powered by {TAIL ~ a power supply}, e.g., a battery pack, located within {HEAD ~ the housing} 
The motor is powered by { TAIL ~ a power supply } , e.g. , a battery pack , located within { HEAD ~ the housing }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD