Why does my AA powered motor show high voltage when running?

Thread Starter

Lumenosity

Joined Mar 1, 2017
469
Hello.
I have a small AA battery powered desktop vacuum cleaner.
It uses 2 double A batteries

When the vacuum is not running and I check the battery voltage (combined) I get 2.95v
But once I turn ON the vacuum, the voltage surges to 7v or more.
I even measure MUCH higher voltage at the motor terminals.
I don't understand this.

However, I'm guessing it has to do with OHMs Law and the change in current?

Thanks
 

MaxHeadRoom

Joined Jul 18, 2013
21,387
A DC motor also generates, and tends to oppose the applied voltage, this is what limits the current rather than purely the resistance of the armature.
Max.
 
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