I also have a Aerobird Challenger. It's been cartwheeled a few times and was never hurt.

I bought the optional bigger battery with more volts. The motor does run faster with the big battery but not longer. In fact, the high voltage battery doesn't run as long, even running at lower motor speeds.

My charger gets hot sometimes so I watch it. But I still have the original charger. The hobby shop has most spares for the aerobird series but I've never needed any.

Enjoy,

Jim