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By john917
#200733
Hi

Regarding the vacuum pump, Power is 12W therefor at 12V, the current should be 1A.

Why does current fluctuate between 0.68-0.74.
By paulvha
#200747
Next to load impact, a DC motor is rotating on "changing magnitic fields". In your assumption 1A is a constant current. With a DC motor there is a moment where the current stops, the magnetic field gets reversed. With a ampere meter it is hard to measure the real current as it not a constant current. Good reading on DC motor : https://en.wikipedia.org/wiki/DC_motor