Its my understanding from reading a bunch that the charge count is based on the actual power fed to the battery. Charge the battery from 50% to 100% twice thats 1 charge count., etc.. However, what I would like to know and can't find any info on is Where is that count stored, in the battery or in the phantom itself. I ask because, I bought a new Phantom 4, and then bought 2 spare batteries off a friend. The batteries are good, most of the time he was flying them I was with him and the count showed correctly (at least it seemed to, though we never kept track of the precise % before each charge). They were both at like 7-8 charge count when last they were in his Phantom, but when I stuck them in mine they both showed Zero. Have not had my Phantom long enough to drain/charge the any of the batteries enough to see if the count is correct, and don't have access to his bird right now to see what it says if I put them back in his, but wanted to see if the count going to zero if you put the battery in a new bird is normal or if its an indication of an issue?