We have charged VEX Battery pack and it keeps going dead after a few minutes of joystick driving.Can we buy batteries for the secondary Battery pack located under the robot? Or is there some reason that the Primary Battery pack is dying so quickly?

Sorry, can you clarify a few things? Is the battery on the robot dying after a few minutes, or the battery in the remote control? Is your remote control the old Radio Control style, or the new VEXnet style, that resembles an XBOX controller?

Make sure that both sets of batteries, the robot and remote control, are fully charged.

How old is your battery? As batteries get older, their ability to hold a charge goes down.

The batteries in the remote and robot are fully charged and are in good shape but we did have a problem with the Primary robot battery that it was loosing power after a few test runs.But now it is doing fine for now.Our question was that for the Tumbler robot assembly there was an alternate battery pack assembled under the robot that requires 6 AA batteries.We were wondering if we could purchase AA batteries for the alternate battery pack and use that incase of our primary robot battery running out of energy?

Thanks for clarifying. We don't sell AA batteries, but you certainly can purchase them from a local store and use them as a backup.

If your robot battery continues to give you problems, and it's relatively new, you can contact VEX Robotics for help and/or a possible replacement: http://www.vexrobotics.com/contact/contact