to be on the safe side follow manufactures recommendations..... My 7.4 5200 mah packs are 8.3 or so volts fully charged If you charge them friday night you should be able to fly a lot .. Since i dont have a one amp load,( i think the its a 250 mah load built in my volt meter) i stop flying at 7.2

Check them after every flight for a few flight sessions to better assess your batteries..