Using a wall timer set for one hour a day is a good way to keep your batteries maintained at full charge. These are pretty cheap and you can charge a bunch of airplanes and field equipment the same way, just hook your timer up to an outlet strip, plug in all your chargers, set it for an hour a day and the next time you want to go flying it is ready to go.

When you get back you can turn the timer on for 15 hours(leave it set for 1 hour-just turn it on and set the dial so it turns off in 15 hours or so) ,this does a full recharge,and then the next day it will start charging for 1 hour again.

Remember to fully charge before starting the 1 hour a day charge.