ID This Motor ???

[Bob La Londe]

http://imageshack.us/photo/my-images/819/cartmotor.jpg/


Came out of an electric wheel chair or electric cart. Seems to run fine in
forward or reverse. Was thinking about using it as a "spindle" motor for an
experiment, but it would be nice to know the HP/KW rating along with the
nominal and peak current requirements.

[neilw20]

[doorknob]

I have no information about that motor, however it does say 24 volts on the picture that was posted by neilw20.

Since it was used in a mobile device such as a wheelchair, and there is a red wire and a black wire going into it, you are probably OK assuming that the motor was designed to be run off of DC.

You could then make a pretty good guess at the rest based on that voltage rating and examining the gauge of the wires going to the motor, and then either doing some research or some "what-if" brainstorming about the amp-hour capacity of a 24-volt battery that would fit on a wheelchair (along with the assumed max run time), you would arrive at a reasonable answer.

[Al_The_Man]

The attached may help acquiring some parameters.
Also test to find out if it is a shunt or series motor, short the conductors and try to spin it by hand if it offers resistance it is a P.M. (shunt) motor, if it were a series wound field motor, care has to be taken as it runs away when off load.
Either way if would be a fairly high torque motor in that application.
Al.

[Bob La Londe]

The attached may help acquiring some parameters.
Also test to find out if it is a shunt or series motor, short the conductors and try to spin it by hand if it offers resistance it is a P.M. (shunt) motor, if it were a series wound field motor, care has to be taken as it runs away when off load.
Either way if would be a fairly high torque motor in that application.
Al.

I know its 24VDC as the buddy who gave me the motor used to service the carts and chairs. The ones he worked on were all 24V. Its been years since he worked on them though, and they had one model with bicycle tires that was much faster than the regular power chairs. He believes this motor came out of one of those. I quick tested the motor on 12VDC and it worked fine in forward and reverse (as it did in the original application).

That is a very interesting document you attached. Very worth saving, and I did. I'll also be printing a copy to go in the "quick" refference folder I keep out in the shop.

I considered just clamping the motor in a vise (with padding to protect the motor of course), and doubling nutting the shaft so I could put a torque wrench on it. Then ball park measure stall torque and stall current at the same time. My problem is I am afraid I don't have a meter that will handle the current. My biggest one is labeled to 20 amps. I could potentially see stall current being much higher than that. If its only a 700-800 watt motor that would place peak operating current close to 30 amps, and stall current much higher.

At first I wasn't certain about the usefulnes of your EMF test since I know the motors operating voltage (about all I know about it). Then it occured to me that I could use it to estimate designed max RPM by spinning it and measuring voltage. When it hits 24VDC (apx) that would be close to the correct max RPM. In all the junk my buddy gave me when he decided to move is a box of pullies. I already have an optical tach. A use for the mini lathe with its variable speed drive. Woo Hoo.

[doorknob]

Can't you simply estimate the stall current by measuring the resistance from the motor terminals (with the motor at rest, of course) and calculating I=24/R (since there is no back EMF at rest)?

[Al_The_Man]

Can't you simply estimate the stall current by measuring the resistance from the motor terminals (with the motor at rest, of course) and calculating I=24/R (since there is no back EMF at rest)?

How to is in the Word Doc.
Using the method listed is an accurate way of getting total resistance, including brush resistance.
Al.

[doorknob]

Expecting me to read before posting is a tall order...

[Al_The_Man]

You know what they say, If in doubt read the instructions.
Al.

[wendtmk]

Read the instructions? Doesn't that violate one of the Man's Rules? Like asking for directions? ;-)

Mark