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