I believe we can go as far as to assume the OP has sufficient common sense to realize that when his battery is getting low he should charge it. If you choose to think that the OP's level of intelligent common sense is so low that he would make the faulty assumption that you should only charge your battery once it reaches 0% and dies, then that is quite interesting and makes me wonder why you consider them to be so stupid. After reviewing some of the OP's posts in the past I had come to the logical assumption that based on prior knowledge, he has a sufficient amount of common sense regarding Android in general to be sufficiently competent to determine when to charge his battery. Considering the fact that he only gets to play with the phone for a little while before his Dad needs it back, it doesn't seem practical to expect him to be able to monitor the device closely enough to follow those precise instructions when such actions are absolutely not necessary to simply calibrate a new phone's battery meter. If the OP uses common sense to charge the device as necessary, I am confident, due to personal experience that the battery along with the phone will turn out fine and display generally accurate percentages.