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I don't know what the "2 small white wires" are, but do you get continuity between the big terminals ? Spin the armature by hand while testing, see if you're getting continuity more or less evenly across all 360 degrees of rotation.
 

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Discussion Starter · #3 ·
Yep. It's hard to tell about all the way around 360 degrees, but definitely every place i stop hand turning has continuity all the way around. The buffer didn't have a regular contractor it had more of a "soft start" mechanism to energize the motor. I think the 2 small white wires have something to do with it. I may need to search for a wiring diagram in the tenant B7.
 

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I still don't get what are the "buffer" and "2 small white wires" you're referring to. This is a brushed PM DC motor, the only wires besides the armature it may have is a temp sensor, which is irrelevant to motor not spinning. Connecting a 12v automotive battery to the motor should get it spinning without any additional circuitry.
 

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Take it apart and inspect/clean the electrical components inside if the 12V battery doesn't spin it. No spark when hitting it with the gator clip?

History unknown or taken from a working Buffer?
 

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Discussion Starter · #7 ·
No spark when touched. Tried it with 24v and 52v. I don't know what those little white wires are either. I actually have 2 of these motors. They are from floor burnishers with dead batteries (according to previous owner). I'll check out the other one. I may try attaching 36v to the other one while it's still installed on the buffer.
 

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There is a serial number and something else engraved in the case above the label... what else does it say there?
In a quick search I found one online listing for the ME0709 (other than Motenergy's usual useless listing), and the cable with the two white wires is not in that one... and that listing says "No temperature sensor", suggesting that another version could have a temperature sensor.
So my guess is that the temperature sensor theory is correct, but it's only a guess.
 

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Temp sensor would probably be a thermistor. Can check for resistance at the ambient temp and then take it outside or something to see the change.

When battery is hooked up, does the shaft show any signs of life ? Can be it be spun by hand while power is connected ?
 

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Discussion Starter · #10 ·
Well now I feel silly. My old jumper cables are apparently broken somewhere in there. I used a different set of cables and sparks flew and the shaft spun like a champ.
Sorry I washed your time.
Now to the spec label.
It says 24-72v and 104 amps continuous duty. Do you think it will pull more current in bursts? I wonder because it says 8.8hp (max) which is about 72v at 104 amps. I'm trying to figure out which controller would work well but I dont want to spend more than necessary for an overkill controller. It's for a little tractor conversion.
 

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I bought a cheap 60A dc motor pwm controller (listed as 100A on ebay but reading the ad it is 60A) think it was $17 maybe less to my Tenant motor out nice being able to run the rpms of motor up and down. Your motor is in better shape than mine. Mine is only 100A continuous. Since the 709 can do 300A for 1 minute, was hoping it would be able to do 250A for 30 seconds.
Later floyd
 

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Discussion Starter · #14 ·
Ya I suppose that just because it looks like an me0709 and it's made for 24-72v, it doesn't mean that it is an me0709. I don't want to go overboard on the controller but I also don't want to limit the motor by the controller.
 

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Well now I feel silly. My old jumper cables are apparently broken somewhere in there. I used a different set of cables and sparks flew and the shaft spun like a champ.
Well, stuff happens. :)

Now to the spec label.
It says 24-72v and 104 amps continuous duty. Do you think it will pull more current in bursts? I wonder because it says 8.8hp (max) which is about 72v at 104 amps. I'm trying to figure out which controller would work well but I dont want to spend more than necessary for an overkill controller. It's for a little tractor conversion.
More complete specs are available, as noted earlier...
... including the (bolded for emphasis) short-term maximum current:
Motenergy ME1003 PMDC electric motor
Brush-Type motor.
Permanent Magnet Direct Current motor
Efficiency 92% at 48 VDC.
Rotation speed 48 RPM per Volt
Rotation speed 570 RPM at 12VDC.
Rotation speed 2300 RPM at 48VDC.
Rotation speed 3450 RPM at 72VDC.
Controller input voltage 12 à 72 VDC.
Constant torque at 0.20 Nm/Amp.
Rated power 11,5kW, peak 20kW (28hp).
Rated current 200A continuous
Rated torque 35Nm at 200A.
Max. DC current 400A during 30sec.
Max. torque 80Nm at 400A.
No temperature sensor
Output motor shaft 7/8"
Shaft key 3/16"
Recommended power cable 70mm² with 8mm lugs
Regen current in brake mode 5,6A per Nm
Brushes life about 1500 hours
Weight 17,9 Kg
Dimensions : Diam. 200mm x 188mm
The torque constant (not "constant torque") of 0.20 Nm/A implies 20.8 Nm at 104 A (approximately regardless of speed) - and a burst of 80 Nm at 400 A - with voltage requirement dependent on the speed and current. The no-load speed at 72 V is listed as 3450 RPM (the result of the motor constant of 48 RPM/V), but at 20.8 Nm the speed would be about 3000 RPM to deliver 8.8 HP.

Real motors are certainly not ideal, but the ideal model of motor constants (listed here as KV = 48 V/RPM and KT=0.2 Nm/A) is still useful, along with the basic relationship of power = torque * speed.
 

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Ya I suppose that just because it looks like an me0709 and it's made for 24-72v, it doesn't mean that it is an me0709. I don't want to go overboard on the controller but I also don't want to limit the motor by the controller.
The motor constant can be approximately determined by applying various voltages (or even just one) and observing the resulting no-load speed. If KV is the same as an ME0709 then KT will be, too (KT is just the inverse of KV, in appropriate units of measure).
 
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