For example, {HEAD ~ the predetermined level} may be set at 20% of {TAIL ~ remaining battery power} 
For example , { HEAD ~ the predetermined level } may be set at 20 % of { TAIL ~ remaining battery power }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL