Skip to content

13. Output device

Group assignment

  • Measure the power consumption of an output device

Motor power consumption measurement demo

For this week's group assignment, I've used the power supply build in voltage, current and power meter to measure the power consumption of the motor. Before ON, power supply panel shows 7.2V, 0A, 0W. After ON, it show 7.2V, 0.3A, 2.16W.

The current consumption of the screen is 0.24A. To know the power, we use the following formula P = V x I.

On this particular measurement, I powered the supply with a DC 7.2V , and we take the consumption of 0.3A. The power consumption show P = 7.2 x 0.3 = 2.16 W.

Normally it show the no load situation of DC motor.

I collect a DC motor with slide crank, brushed electronic speed controller (ESC) and servo test following the ESC user manual.

Brushed electronic speed controller connections following the user manual. First test, we set the Servo tester with PWM 60%. The panel show 7.2V, 0.15A, 1.08W. Second test, we set the Servo tester with PWM 100%. The panel show 7.2V, 0.25A, 1.80W. The power consumption is increasing proportional according to the PWM percentage.

Final test, we add a can at the end of the slide crank. The motor is blocked by the can. It is full load situation for calculate the power consumption. The panel show 7.2V, 0.92A, 6.62W. It is about 3.5 time no load power consumption.

Last update: July 3, 2021