I am very noob to Electronics, I am planning to make a Robot, I have 2 12 V motors, 1 RPi and 1 Ultrasonic sensor

I am very confused on how to calculate the power for Motors as it is 12 V and Pi can't power them up? Also can you please help suggest which battery should i use, Lipo or Alakyne Battery Cells?

For Pi - I will power it with my Mobile Power bank.

Motor Module which i am planning to use https://www.electronicscomp.com/l298n-dual-h-bridge-dc-stepper-motor-driver-controller-module

  • \$\begingroup\$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. \$\endgroup\$
    – Community Bot
    Commented Sep 12, 2021 at 14:35

1 Answer 1


The motor will operate over a fairly wide voltage range, but speed is proportional to voltage. The linked motor specification chart is based on 12 volts, so that would be the best choice to try. The chart lists no-load current at 60 ma and maximum load current at 300 mA. There is no indication if the maximum is a momentary current or a continuous current. 300 mA at 12 volts is 3.6 W. The mechanical power of 2 kg-cm at 200 RPM is 4.1 W. I suspect that is more than the motor can do continuously.

Alkaline AA cells have a lifetime of 1 to 2 amp-hours when discharged at 0.5 amps. That would mean 2 to 4 hours lifetime.

You should probably measure the motor current while it is driving the actual load that you intend to drive with whatever batteries or other power source is most convenient. Then make a final decision based on expected ongoing use details.

  • \$\begingroup\$ Thanks for great explanation. I want to know what power source do I need \$\endgroup\$
    – RahulAN
    Commented Sep 15, 2021 at 13:26
  • \$\begingroup\$ I want to know what power source do I need, from what I understand is I need a battery of 4.1 W, 12 v supply, is this correct? \$\endgroup\$
    – RahulAN
    Commented Sep 15, 2021 at 13:32
  • \$\begingroup\$ The information for the motor is inconsistent and unclear. The maximum continuous current is 0.3 A at 12 V or 3.6 W input power. The rated output is 2 kg-cm at 200 RPM or 4.1 W it I calculated correctly. You can not have higher output power than input power. The input power is more likely to be twice the output power. If you connect 8 AA cells in series, you will have 12 volts to test the motors. AA cells can probably put out enough current to overheat the motors and will last long enough to find out how much current you really need. \$\endgroup\$
    – user80875
    Commented Sep 15, 2021 at 15:32

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