The field of the invention generally relates to cell phone battery systems that ensure a user has {HEAD ~ reserve cell phone battery power} for {TAIL ~ emergency calls} 
for
The field of the invention generally relates to cell phone battery systems that ensure a user has { HEAD ~ reserve cell phone battery power } for { TAIL ~ emergency calls }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL