NO! if its not the batteries then next check the blades..Bad blades will cause huge powerloss. I've gone through this before with mine and it turned out to be the blades.

If your batteries arn't balanced then its probably your charger. E-flite chargers are cheap, maybe invest in a better one. I am working on a theory on how to rebalance them but its going to take me a while to test it. I'll keep you posted.