Batteries tend to last about 20+ hours of gameplay for me. Obviously depends on your brand...
If you are playing so far from the TV, one option is to have the sensor bar on a table or on the floor in front of the TV. Say 5+ feet in front of where you want to be. Where we have the wii, the room isn't big enough to go over 10 feet so never had that problem.
(That is assuming the problem you are experiencing with the sensor bar, is the controller detecting it, and not bluetooth range...)








