I'll keep this short.

The stock batteries from E-Flight are only designed for the stock Heli.

You would be better served by getting better batteries.

You want 15C+ and 900 mAH. Get something that is designed for the CX2, like www.readyheli.com sells.

If you decide that you are hooked on this hobby, start looking for a better charger / balancer than what E-Flite supplies.

PM me if you want more info.