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>> Home > Forum > Electrical Related > How do I find out the voltoge of my motor without it burning out
How do I find out the voltoge of my motor without it burning out
Author Message
(Fleet Admiral!)

Forum Posts: 110
5th Oct 2017 14:42  
>> Permalink

I have several motors that all look very nearly the same. One I know is a Graupner Speed 600 which is 8.4v but of the other 2, one is said to be 12v(was working with an 11.1 lipo) and the other one is unknown. It has a built in cooling impeller so probably came from an electric tool of some sort. Neither of these 2 have any markings or labels. Is there any way that I can test them for their normal working voltages without endangering them?


(Fleet Admiral!)

Forum Posts: 2227
5th Oct 2017 16:30  
>> Permalink

Deja vu?? Are these the MFA drill motors we discussed some time ago?
Doug 😎

Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change,
the Courage to change things that I can, and
the Wisdom to know the difference!
Dave M
(Fleet Admiral!)

Forum Posts: 1527
5th Oct 2017 19:19  
>> Permalink

Hi Chris
I know of no easy way for you to determine the voltage.
However motors do have a coil resistance value measured across the terminals.
Also if you can see the coil windings a thick wire usually indicates a motor designed for high speed and current.
A thinner wire may produce a motor with lower speed and less current and more tork.
If you check the Graupner and look at the windings this may help you identify the other two.
In my experience it's usually too low a voltage that's the problem resulting in slow revs and little if any tork.
At the other end of the scale too high a voltage will result in very high revs and lots of sparks from the brushes. In this case if you continue to apply the volts you will damage the motor.
Many electric drills were powered by motors rated at 9v and did indeed have an impeller cooling fan.
That said Mabuchi and Johnson produced a vast range of motors all looking similar on the outside but wired very differently inside depending on the ultimate use.
I suggest you try with progressively higher voltages and assess which is best for the two unknowns.
Finally most motors are designed to work over a range of voltages so I usually measure both the upper and lower values so I can select the right motor for a particular model.

Live long and prosper