7.2v bettery life

Our team is finding the battery life of the 7.2v batteries has gotten shorter to the point where we can run the robot for 3-4 minutes, and then the cortex battery light begins blinking yellow.

  1. Is this normal? FYI, on our gripper-style 'bot we use four 2-wire 323 motors geared for high speed, four 3-wire motors for the arms, and two motors for the claws/hands.

  2. Suggestions as to how we can re-program the battery for a longer use?

  3. What difference, if any, does it make to battery life to charge the battery under Safe mode rather than Fast mode?


  1. There are 3 types of 7.2v batteries, and you don’t say which you have.
    You can check the wiki or search for Quazar’s posts on battery life to compare your experience with his.

  2. You can try letting it discharge completely with a PIC or a Cortex running a motor with low loading until it shuts itself off. Recharge on safe mode, and repeat 2 times. Let us know if it helps.

  3. Safe mode is reputed to be easier on the batteries, since it doesn’t heat them up as much.