Currently I am using a 9 Volt Duracell A one like this: enter image description here

I am using it to power a motor driver which contains 2 motors within. I can see where the main problem is coming and that is to do with that the voltage is not big enough. But I don't understand why this is. I see in the manual for the robot that I am building it is using a smaller voltage battery than what I am using. I tried using another set of batteries but the motors did not move at all then. The 9V Duracell battery that I am currently using has only been used for about a week (so it probably hasn't ran out), its practically brand new.

  • Voltage is not the be all and end all. Power density and current delivery are more important, and PP3 batteries fail at both.
    – Majenko
    Oct 23, 2020 at 17:02
  • that battery contains six AAAA cells ... think about the difference between AA and AAA
    – jsotola
    Oct 23, 2020 at 17:26
  • 1
    This question has been asked several times on this site. A quick search gave me this question and this question. Both explain, that 9V block cells are not up to the job of driving motors
    – chrisl
    Oct 23, 2020 at 17:58

1 Answer 1


It is likely not a question of the voltage being "big enough". You do need to feed the correct voltage to your robot, but max current and capacity are also very important.

Those "9V transistor batteries" have very low peak current and very low total power capacity (measured in milliamp-hours, or mAh.) They are not up to the job of powering motors. You could easily drain a 9V battery like that in 15 minutes, much less a week.

You should connect 6 D cells in series, and use that instead. That would give you enough peak current and total capacity for your robot.

  • Does this mean that I have destroyed my 9V battery Oct 23, 2020 at 20:51
  • Used it up, more likely. If you have a volt meter, measure the output voltage. If it's much less than 9 volts, the 9V battery is too weak to be useful. Those are disposable, and don't have much "juice" even when they're new. Toss it and get a bigger battery.
    – Duncan C
    Oct 24, 2020 at 1:03
  • Oh dear........ Oct 24, 2020 at 14:09

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