how to test a motor

[Sergio]

Emery cloth is not recommended for cleaning commutators.

I think the main reason is that emery crystals are much harder than sand and can embed themselves in the soft copper and mica around the segments.

Those particles can later have a bad abrasive effect on the brushes.

Garnet commutator paper is typically recommended as most sandpapers these days seem to have alum-oxide.

If you can find old school sand paper it will work best.

[cjpenny89]

ok so which is the correct way to test this serpex motor? I tried test 1 last night
I will clean it up before I do.
Test 1
You have a SepEx motor. So don't connect it up like a series motor. And all SepEx motors are not the same as far as field strength and resistance. But if you are careful and watch it, like be there if things start to get hot and smell ripe, you can test it with a single 12 volt battery. I have some nice power supplies available, so use those, one supply on the armature and one on the field and can adjust them separately. If you have this available, do it. Adjust the field to about 6 to 8 amps and bring the armature voltage up slowly. Watch RPM and raise the armature voltage such that you see about 2000 RPM. You can then adjust the field voltage while leaving the armature voltage alone. And you can see the effects of field weakening. But keep an eye on the RPM and keep it under 4000, to be safe. The lower the field current, the higher the RPM. And you may find that you trip the armature power supply if you increase the field current too fast because it regenerates into the power supply.

So, you probably don't have 2 power supplies. Just use a 12 volt battery. Hook the field up first and disconnect the field last. Remember this. O.K. So connect F1 to B+ and F2 to B-. You'll see a little spark. Endure it. It won't hurt. Use like #16 wire for the field to battery. Should be at most 10 to 12 amps. If the wires get hot, better shut down.

Now you have the field excited. You can use the same battery for the armature or a different one. You probably want a little heavier wire, like jumper cables. Connect A1 to B+ and A2 to B-. Again you'll get a spark. And the motor will rotate. It will accelerate quickly and tend to rotate on the bench. You should have nothing connected to the shaft, maybe those pulleys are o.k. You can strap it down or block it so it does fall off onto your foot.

So now you have 12V to the field and 12V to the armature. Should be rotating smoothly, maybe 700 to 1000 RPM. Should be no big sparks anywhere, or smoke, or bad smells. If so, shunt down, ARMATURE FIRST, then the field. If you disconnect the field first, you might get a speed up of the armature and then a real high current in the armature and could damage stuff. Same on start up. FIELD FIRST, then connect the armature.



Test 2
To test run a Sep-Ex (regen) motor. The motor needs to be bolted to the rear end, NOT unbolted and sitting on the work bench

Remove all cables from the motor; connect a jumper from A1 to F1 and a jumper from A2 to F2. Connect 12 to 24 volts, positive @ A1/F1 and negative @ A2/F2. Swap F1 and F2 to change rotation direction.

NOTE: some Sep-Ex motors are labeled S1 & S2 in place of F1 & F2

[cjpenny89]

I will clean the Armature but should I clean the rust off the field magnets and that part of the motor as well? emroy type cloth or sand paper? or leave them alone?

[Volt_Ampere]

The other rust won't hurt anything. Just clean it up and make sure the brushes and the brush holders are clean. The main issue with the rust is probably your bearing which you are replacing anyway. Cleaning up the commutator should be all your motor needs on the electrical side. If it is pitted much you might want to take it to a motor repair shop and let them clean it up on a lathe.

[cjpenny89]

Thank you Volt_Ampere! I will let you know how this turns out

[ElHuaPo]

Thanks to all for the info on how to test a golf cart electric motor! I was given an old Yamaha (1998 G19ES, I think) that had sat for years. I could read the resistance of the motor leads, they weren't shorted or grounded and the motor nameplate said "Shunt Wound GE". So the info posted herein has been just what I needed to make sure my motor was OK. Indeed, it runs slowly in both directions on 12vdc after following these instructions, so now it's on to testing other parts to find out why it won't operate normally. Many thanks.
BTW: I forgot to release the brake at first, very necessary----oops!

[TightwadDIY]

Originally Posted by rib33024

To test run a Sep-Ex (regen) motor. The motor needs to be bolted to the rear end, NOT unbolted and sitting on the work bench

Remove all cables from the motor; connect a jumper from A1 to F1 and a jumper from A2 to F2. Connect 12 to 24 volts, positive @ A1/F1 and negative @ A2/F2. Swap F1 and F2 to change rotation direction.

NOTE: some Sep-Ex motors are labeled S1 & S2 in place of F1 & F2

CAUTION:

Allowing a motor to spin @ high RPM can cause catastrophic failure!. Only do this test with the motor bolted to the rear end

Put vehicle in TOW mode before attempting testing process if vehicle has TOW switch . . .

Thanks for these step by step instructions. They were very helpful.