18V motor running of a 19V laptop charger

I do not understand how people can do this.
 I have wired an 18V portable motor directly to a 19V 3.16A laptop power adapter and the motor kicks and kicks constantly but does not spin. The power adapter has more than 19V tested with a multimeter.
I did see reports that power adapters for laptops have a controller built into them to do some kind of regulating and thought this might be a problem and this motor has spun ok at times.
 What could the problem be?

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jfryar3027221 days ago

There are a few things:

First, an 18V motor could, and most likely is a fairly large motor (correct me if I am wrong). A motor like that could try to be pulling upwards of 800 amps! For example, the starter in a car runs on 12 volts, yet on average, it pulls about 300 amps.

Second, is there anything broken in either? Does the power supply work for the laptop? Could the motor be bound up (e.g. seized up bearings, a jammed loose part, etc.)?

If this doesn't make sense, please let me know and I'll do my best to revamp my comment. I hope you can figure it out!

rickharris28 days ago

I am guessing the laptop power adaptor has a DC output.

What type of motor have you connected DC or AC.

3.16A may not be enough to start a motor under load.

Testing the voltage off load isn't reliable.

The power supply will be a switched mode power supply input 110 to 240 volts AC output 19 volts DC.

My guess is it is a DC motor. I can't say that I have heard of 18V AC, but if someone has, let me know!

iceng27 days ago

What does your motor do when you try it on your 12V car battery ?

Starting current for DC motors can be 10X running current, supply sees spike, and shuts down, then repeats. You might try a big capacitor on the output of the supply.