When you say "one battery is powering", does that mean you have two battery packs per chance? Your post sort of implies that you have two packs. But, most likely, you have one battery pack.

What you have to do is determine several things:

1. If you have the right battery pack for what you are planning to do (amp-hours, voltage, and composition (LiPo, NiMH, whatever).

2. If you have the right ESC that matches the plane weight with the current draw you are going to encounter in normal flight.

3. If you have the right motor that matches all of the above.

There is a weight/power ratio that is compatible with your electric plane setup and flight style (normal flight, agressive flight, or 3D). You have to make sure that for the given weight (combination of all components.. airframe, servos, ESC, motor, and battery) and flight style, will work with the motor/ESC/battery pack you have chosen.

It's not as easy as you may have been led to believe. You may have burned up either the motor or the ESC. You have to do your homework to make sure you have the right combintatoin.

CGr.