I am building my first 4wd vehicle with Adafruit motor shield with one Ultrasonic sensor and one small servo to move sensor.

I am facing some problems.

  1. Bought 4 motors (2 GM9 and 2 GM3), found the difference when start running and GM9 were running double the speed of GM3. Tried to slow down th eGM9 with speed in code but now one of the motor stop many times while other run.
  2. Running spearate power for Arduino (now USB) and 9v batteries for motorshield. Should I remove the jumper on motor shield as found that after removing 9v battery, its getting some volts from Arduino and motors running very slowly.
  3. Servo motor is not running at all. While its pins are according to the circuit.
  4. Should 9v batteries will be OK to run 4 GM9/GM3 motors + 1 small Servo? if not please recommend any other.
  5. When running I feel small smell from boards, nothing is hot, is it a problem?

Too many questions but tried to put in one place.


  • 9v batteries can't produce much current. Better use a pack of AA NiMH batteries. If a new board gets warm it might smell a bit. Should go away after a while, but keep checking that nothing gets too hot.
    – Gerben
    Feb 17, 2015 at 17:20
  • Thanks for reply. what about the jumper on motor shield? its removed now but still getting current from Arduino.
    – Builder
    Feb 17, 2015 at 18:30
  • Removing the jumper would be a good idea. With the jumper, the arduino would run on the same 9v battery instead of the usb power. Sudden spikes in power draw could crash/hang the arduino. I don't see how the motors could be running without the 9v battery attaches. That one puzzles me.
    – Gerben
    Feb 17, 2015 at 20:20
  • The Arduino is connected to USB to PC, but motorshield is with 9v battery. When I disconnect motorshield from battery the wheels runs and green light on sheild is still on.
    – Builder
    Feb 17, 2015 at 21:20
  • 1
    yes I checked with/without both. I am afraid if I connect 6 AA cells now it could burn one or both boards. I checked the adafruit site as well for connections.
    – Builder
    Feb 18, 2015 at 14:32


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.