determining whether a discharge level at which {TAIL ~ the capacity} of {HEAD ~ the rechargeable battery} can be learned is reached 
determining whether a discharge level at which { TAIL ~ the capacity } of { HEAD ~ the rechargeable battery } can be learned is reached
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH