# RS-550 motor only spinning in short bursts

I bought four of these motors, brand new and they all have the same issue. Amazon RS-550 , Amazon RS-550

I am a bit confused by the Horsepower: 100 watts claim. The motors require 12V from various specifications I found it requires between 0.8A and 1.3A as high peek. I have two variable power supplies:

One which has the following selection: 12V 4.3A 50W all the way to 24V 2.5A 60W

One which has: 3V 1.5A all the way to 12V 1.5A 18W

When connected on any configuration the motors just spin in bursts they spin up and slow down and spin up and slow down with no continous movement.

What am I missing here? Do I have an inadequate power supply? But looking by voltage and amps it should be enough to at least spin the motor under no load.

Looking at this video the power supply should be able to power the motor: https://www.youtube.com/watch?v=dfiIY1I_MY0

• do you have a question of some kind? ... sounds like an inadequate power supply Jul 24, 2022 at 15:29
• @jsotola Yes what power supply do I need to drive this thing :/ Sep 18, 2022 at 10:36

I am a bit confused by the Horsepower: 100 watts claim.

You're right. That's the first clue of a dodgy specification. "Horsepower" should be "power".

The motors require 12V from various specifications I found it requires between 0.8A and 1.3A as high peek. I have two variable power supplies:

You need to measure the motor DC resistance. From that you can calculate the startup current from I = V/R.

Your power supply will need to reliably supply that much current until the motor gets going. Once running the back-EMF will cause the current drawn to reduce.

• Can I check its resistance using a multimeter ? Sep 18, 2022 at 20:40
• Hm I set my multimeter to 200 Ohm, I placed the tips on the motor and get a reading that goes starts at 10-30, then rapidly falls to around 2 and then slowly falls to 1.0. Going by your formula this would basically be: I = 12V/1.0 = 12A Seems a lot for such a small motor. Sep 18, 2022 at 21:06
• 1 ohm is plausible. You should have done this with at least one of the motor terminals disconnected from the control circuit. You should also check the meter lead resistance by touching them together and subtract that value from the measured resistance of the motor windings. In any case you can see why your power-supplies are struggling. Sep 18, 2022 at 21:25