Sorry, forgot about the last part of your question. As to how long to charge a battery is concerned, you are using a 650mah battery. Your charger is putting out 50 to 100 mah (it will tell you on the front of it. So, if it is putting out 50man, devide 650 (your battery's capacity) by 50 (the output of your charger) and you have 13. So charge for 13 hours. This is assuming your battery is dead right from the start. That probably isn't the case, so it's anybody's guess as to how long to charge. Most of us charge for five or six hours and then check with one of the meters mentioned in my first response. A 4.8 volt battery, unloaded, should show approximately 5.5 volts unloaded and drop to 5.25 volts loaded or there about. As said before, if it is below 4.8, don't fly.