a battery mounted in the case and connected to {TAIL ~ the power input socket} so the external battery charger can charge {HEAD ~ the battery} 
a battery mounted in the case and connected to { TAIL ~ the power input socket } so the external battery charger can charge { HEAD ~ the battery }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD