Spinning the shaft of a DC motor with rotary tool collet or chuck?

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What are the possible outcomes if I insert the shaft that usually spins a fan blade etc into the tip of my Dremel and turn it on? Will it create electricity and if so what would happen if I shared it out by touching something metal to both +/- at the other end of the motor?

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2 Answers

Anonymous 0 Comments

It would generate electricity, yes. Often motors are designed to operate as generators. The spinning of the motor does create an electric field that resists the rotation of the motor. This is known as “generator action” and it’s a known thing in electrical engineering.

In fact, a lot of electric vehicles turn this bug into a feature called “dynamic” or “regenerative braking.” As the motor spins while coasting, it creates electricity. You can harness that electricity by removing the power source and attaching a load to it and use it to charge the vehicle’s batteries. This impedes the motor and slows it down. I’ve worked on trains that have massive [braking resistors](https://www.mdresistor.com/wp-content/uploads/2020/12/Resistances-de-traction-fixee-sur-une-rame-min-1.jpg) on the roof. If the train can’t recycle the electricity generated by braking, it turns it into waste heat by running it through that massive resistor.

So yes, you could generate a current by spinning a motor by using an electric drill. This will be far less efficient and generate a much lower current than what comes out of the wall, because of thermodynamics

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