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DC Motor Burning Issues? Answered

I connected 6 Volt 4.5 AH Battery to a motor directly and that burning electronic smell came.
Should i limit the current?
If so, Then how?



Best Answer 2 years ago

Ohhh, magical motor smoke! :) Well either something was wrong with the motor or you are powering it with too much voltage, like rickharris said. However I have found that simple brushed DC motors are pretty rugged and can generally tolerate much higher voltages than they were designed for, so long as there is not a heavy load connected to the shaft.

You may need to get a new motor or rewind that one. if it smoked you probably burned off the enamel on the wires and it would need to be rewound. That generally is not worth the effort unless it is a very unique special part and no replacements exist.

You will need to know what voltage that motor is. To limit current, you can add a very large (high wattage) resistor in series with the motor, which is not the best but that will work, use a beefy linear voltage regulator (better but just as inefficient) or PWM (best).

...except a series resistor destroys the motor's ability to regulate speed, because now the speed is more sensitive to load

It certainly won't do the motor any favors but it is the cheapest option. This device aVe reviews literally uses nothing more than a rheostat in series with a shaded pole motor for speed adjustments.

Question: Would an ideal DC brushed motor with 0 winding resistance have very high torque and very little change in RPM vs torque if provided a constant voltage?

Precisely V=E+IR, torque is proportional to I.

If R=0, V=E, and Torque is independent of terminal voltage (and speed IS dependent on terminal voltage note)

That's interesting, so it's that internal resistance the determines the torque curve of the motor. So that means the rotational speed of the ideal motor will stabilize and be proportional to the voltage?

In a battery powered system you should either match the battery (consider both minimum and maximum voltages!) and motor rating, or use a pulse-width-modulating speed control to reduce the effective (average) voltage applied. Linear speed controls will just waste battery capacity generating heat

I assume then too higher a voltage for the motor - Reduce the voltage and the motor will take the current it needs.