# Surplus DC motor - need help identifying



## Tesseract (Sep 27, 2008)

Electric_Rav said:


> I found a DC motor at a surplus store and I need help identifying its capabilities. There were two motors and the smaller one had a tag on it saying voltage was 48 and the amps were 50. This motor was larger but had no tag on it. My latest plan was to add this motor to drive one of the wheels on the rear of my 97 RAV4 to make it a EV only under 35mph with 48 volts. I'm wondering if this motor will do it. (if it works) It looked like it was about 8 inches in diameter and about 13 inches long. It weighed about 40 pounds and has a hydraulic pump on it. $175



Pull of that terminal cap first so we can see if it has 2, 3 or 4 terminals and what they are labeled, then hopefully you have a multimeter to do a couple of simple tests.


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## Electric_Rav (Aug 11, 2008)

When I was there I did not have a multimeter but I did pull the terminal cover off and it just had two terminals. The place had no idea if it worked or where it came from but did say that if I bought it I could return it in 10 days for a full refund. Even if we can figure out what voltage it is, the brushes might be bad or some windings might be shorted. On the other hand if this motor worked I don't think $175 is too bad of a deal.

I live in a cold climate and I need to bring the kids to school 5 days a week and drive to work 2 days a week. So for 3 days I only drive 4 miles round trip per day and want to do this in EV mode to save the wear and tear on a cold engine and exhaust. I would use a vacuum pump for brakes and ceramic heater for heat. (or preheat the vehicle) If that motor is 48 volts, I think just 4 12 volt batteries with a heater blanket around them should be good. With the batteries, controller motor and other things I'm hoping to keep this below $2000.


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## major (Apr 4, 2008)

Electric_Rav said:


> I found a DC motor at a surplus store and I need help identifying its capabilities. This motor was larger but had no tag on it. It weighed about 40 pounds and has a hydraulic pump on it.


Hi Rav,

First off, looks like a close coupled pump. Meaning the motor likely has an internal spline or tang drive. No output shaft for you to work with. You say a 2 terminal motor. Means it is unidirectional. Correct rotation for you? Could be series or compound wound. Do you care? 40 pound motor at 48 volts, I'm guessing, maybe 4 or 5 hp rated, maybe 10 to 12 peak. Enough for a RAV4?



> My latest plan was to add this motor to drive one of the wheels on the rear of my 97 RAV4 to make it a EV only under 35mph with 48 volts.


Drive one rear wheel? Sounds difficult to implement. That small a motor might do the job for under 35 mph when using the transmission, but direct drive to a wheel, I don't think so.

Regards,

major


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## Electric_Rav (Aug 11, 2008)

I'm worried about the possibility of a spline shaft too. I guess I won't know unless I buy it and take the pump off.

Drive one wheel? I know, I have not worked though all the possibilities yet. My Rav4 is currently a front wheel drive only and I can get the real differential, hubs and axles from a local salvage yard for $200. The suspension seems to be the same between the 4WD and 2WD version. I could perhaps couple the motor directly to the differential input shaft and that may give me the gear reduction needed but I don't want to spin the motor with the wheels over 35mph. Too much drag and wear on the motor plus the RPMs would be too high so I would have to use some sort of clutching system. If I used the differential for the reduction I would probably have to drive both wheels. If I can get a gear reduction gear box, I may just drive one wheel. I live not that far form a combine (harvester) junk yard and there are all sorts of gear boxes in those things. Getting everything to fit together might be the hard part. 

And for what? My Rav will still just burn gas primarily. I bought this Rav with the thought of converting it completely to electric but quickly found out that getting a range of 80 miles for less than $10k is almost impossible.


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## iggymo (Apr 17, 2009)

Hi All,

Rav, I hate to say it, but I just bought the motor. The guy at the store made me an offer I couldn't refuse.
It is a two pole motor, with four sets of brushes. The brushes are connected in groups of two. The output shaft is a spline insert, so will need to be modified. Motor does work, I put 12 volts at 20+ amps into it and it spins up nice and settles about 14 amps unknown rpms. 

My question is, how do I re-wire it so I can reverse the direction?
What else do I need to check to learn more about this motor?

It is going into a 48 volt Ford Fstiva EV project. (Hopefully)

Thanks!

Iggymo


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## Electric_Rav (Aug 11, 2008)

Welcome to the forum!

Good deal on the motor! I decided to pass on it. Too many unknowns and too little money for the overall project. 

For months I've wanted to start a group of like minded folks in the Sioux Falls area. Maybe even a chapter of the Electric Auto Association. Interested?

I'd also love to see your project as it progresses.

We can continue here or use the private messaging capability of this forum.

I'm glad the motor works.


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## major (Apr 4, 2008)

iggymo said:


> My question is, how do I re-wire it so I can reverse the direction?


Hi iggymo,

First off, call it a 2 terminal motor. Poles refer to the magnetic things inside the frame. It is a 4 pole motor with 2 terminals, which makes it unidirectional. And the wrong direction for you, so you say.

To reverse the direction of rotation, you need to reverse the polarity of the either the field or the armature (brushes), not both. When you switch the polarity (battery + and -) on the 2 terminals, it still rotates the same direction, right? That is reversing the polarity of both the armature and field.

Probably the easiest is to reverse the polarity of the armature. This is done at the brushes. There are 4 brush holders. Let's use a clock to describe their positions. At 12, 3, 6, and 9 o'clock. Got that? So, the brushes at 12 and 6 o'clock are wired together, call it positive. And the brushes at 3 and 9 o'clock are wired together, call it negative.

You will need to rewire the leads coming from the field to the brush holder and from the brush holder to the terminal. Switch those around so the brushes at 12 and 6 o'clock are negative and the ones at 3 and 9 o'clock are positive. That will reverse rotation.

This can be accomplished simply by rotating the comm end head (CEH) (the casting supporting the brush holders) by 90 degrees. But, undoubtedly, the wires connecting the brushes to the field coil and terminal won't be long enough. And those wires are probably soldered. So, get out the torch. Or take it to a motor rebuilder with a copy of these directions.

Also, the motor may have a brush shift, commonly called advance, to improve commutation (reduce brush sparking). Typically about 5 degrees. It is unknown if this motor has that. But if it does, you will need to offset the CEH or brush holder ring to compensate, moving it about 10 degrees.

Pretty simple 

major


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## iggymo (Apr 17, 2009)

Hi Major,

Yes, you are correct, Ishould have said it was a two terminal, four pole motor. From what I can see it is a series motor, but I may be mistaken, I will add a diagram of what I see the wires doing below. What I see is a connection from one terminal going to the armature, then through the arm, and down into the motor, the other terminal goes down into the motor. The diagram reflects what I THINK is going on. 

If I want to reverse it I should swap the polarity on the armature as you said, that would be the easiest to do. I had thought about using the motor for reverse, but I can easily use the transmission for that.

How do I found the true HP rating of this motor, and how can I safely figure out how many amps I should expect to be working with? I plan on using a solid state controller, although contactors and batteries could work too. I am also on a budget like most others trying to build an EV, but I think I have a good start with a $100 car and cheap motor (If it works for this purpose).
Thanks for you help... Iggymo (Steve)


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## iggymo (Apr 17, 2009)

Also... I am pretty sure it is Russian in origin, the smaller one had cyrillic writing on it. I will get a pic of the smaller one and the nomenclature plate on it. i looked around for the sticker on this one, but it is long gone in the store.
-Iggymo (Steve)


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## major (Apr 4, 2008)

iggymo said:


>


The second diagram looks more like it. So to reverse it, + would have to go to 12 & 6 and 3 & 9 to the field coils.



> How do I found the true HP rating of this motor, and how can I safely figure out how many amps I should expect to be working with?


Read the name plate  Post up some good shots and measure brush size. Count the number of comm bars. I'll give you a guess.

major


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## iggymo (Apr 17, 2009)

Hi Major,
Thanks for the reply. I snapped some pics and did some measyring and dissasembly too. Here's what I got:
65 commutator bars, and the brushes are about 9.9mm x 19.9mm in sets of two, so they are like 9.9mm x 39.8mm total surface area for each set contacting the commutator.
Norice the flat copper wire onthe armature, is this uncommon? I thought most of the wire used in motors was plain jane round copper enamled wire? One thing I have to say is this thing is dirty! take a look at the inside front cover and the spline shaft hole...ick!
The one picture shows the bolt holes to turn the rear frame to adjust the brushes.
Thanks for the time!! I appreciate it.

-Iggymo (Steve)


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## iggymo (Apr 17, 2009)

Electric_Rav said:


> ...
> For months I've wanted to start a group of like minded folks in the Sioux Falls area. Maybe even a chapter of the Electric Auto Association. Interested?


 
I'd love to meet with people who are interested in the same things. I'd love to learn as much as possible about this stuff. I have thought about starting a group as well, but fear that I may not have enough time or resources to manage another obligation. I thought about a Sioux Falls 'MAKE' group on several occaisions for folks to talk about any kind of projects they are working on, more of a meeting of the mids if it were. Maybe even have a 15 minute presentation each meeting and then 'shop time'.... who knows, might work? I am trying to get a motorcycle rebuilt and sold to fund the EV project. Hope fully I will get the EV done this summer and drive it around as much as possible before it gets too cold (Maybe even drive it all winter!)

-Iggymo (Steve)


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## major (Apr 4, 2008)

iggymo said:


> 65 commutator bars, and the brushes are about 9.9mm x 19.9mm in sets of two, so they are like 9.9mm x 39.8mm total surface area for each set contacting the commutator.


Hi Steve,

Motor looks pretty good. With 65 bars, and armature coils, and that size brush contact, I'd guess we're in the range of like 125 to 150 amps for a one hour rating, ventilated fan cooled. Maybe double that for a 5 minute rating. And it should be able to do 500 amp blasts for accelerations. Comm has a nice film. Keep your fingers off of it and leave it alone. Brushes look a little short, but probably have plenty of life for you.



> Norice the flat copper wire onthe armature, is this uncommon? I thought most of the wire used in motors was plain jane round copper enamled wire?


Called a bar wound armature. Common for these fork lift motors and cranking motors. That is a good thing for ya. These bar wound armatures are usually quite robust.



> One thing I have to say is this thing is dirty! take a look at the inside front cover and the spline shaft hole...ick!


Yeah, fretting corrosion. I'd replace that bearing. Weren't going to used that drive spline anyway, were you?



> The one picture shows the bolt holes to turn the rear frame to adjust the brushes.


Mark that position before you disassemble it. That is where you will need to adjust when you reverse rotation.

Regards,

major


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## iggymo (Apr 17, 2009)

Hi Major,

Thanks again for the info, I already have motor garde bearings on order and they should be here soon. The one bearing would not make a full revolution without binding up completely. I am happy the motor had enough guts to power through the bad bearing spots.
As for not touching the comm bars, too late. I polished a little spot to see what they looked like. They do have some grooves in them, should I just get the rotor turned and cleaned up, or should I stop now and just use it as is. I plan on doing a good cleaning of the rest of the motor, and then a nice coat of black paint to make it shine....unless I shouldn't. 

Thanks!,

Iggymo (Steve)


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## major (Apr 4, 2008)

iggymo said:


> As for not touching the comm bars, too late. I polished a little spot to see what they looked like. They do have some grooves in them, should I just get the rotor turned and cleaned up, or should I stop now and just use it as is. I plan on doing a good cleaning of the rest of the motor, and then a nice coat of black paint to make it shine....unless I shouldn't.


Unless it is badly grooved or otherwise damaged or contaminated, leave it alone. For grooving check, use an old fashioned wood pencil, sharpened to a point. The graphite "lead" in the pencil won't hurt the comm. Just run it across the comm bar and feel for bumps. Chances are, you're good to go.

As for cleaning the motor, soap and water is best. Keep solvents out of there. Doesn't hurt to get the comm wet. Just don't scrub it. Best to dry the motor out in the oven at like 200F for like 4 or 5 hours, but if the Mrs won't agree, room temp dry for a few days. Blow it out with oil free compressed air and get any standing water out of there to prevent rust. Maybe use a hair dryer at first. I'd only paint the outside. Oh, yeah, when cleaning, remove the brushes and just dust them off. 

And replacement bearings should have high temperature grease and seals. And you'll need to press them on the shaft supporting the inner race, not hammer them with a 2 x 4.

Regards,

major


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## Electric_Rav (Aug 11, 2008)

iggymo said:


> I thought about a Sioux Falls 'MAKE' group on several occaisions


Count me in! Now... to find the time. Busy Busy.


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## iggymo (Apr 17, 2009)

Hi Major,

I think I am going to take the whole thing to Malloy Electric here in town (Sioux Falls) and see what they would charge for either modifying the shaft, or replacing it. And while it is there, I will have them press the bearings in the shaft, as I would only be able to beat them on with a big socket and a hammer (Too much room for stupid mistakes). What do you think a fair price for a new shaft or modification should be? If they are too much, what would you charge? If you want to keep business off the forum, just let me know and we can figure out a more private way to discuss this.

Thanks again, my knowledge of DC motors is growing by leaps and bounds!

-Steve (Iggymo)


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## iggymo (Apr 17, 2009)

Hi Rav,

I'll keep you posted on the status of the 'MAKE' group. Do you get the magazine?

-Steve


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## iggymo (Apr 17, 2009)

Hi Major,

A little more research tells me this motor is made by Kostov, and the data inside the motor on the end plate says K5 EC 52.22.28. If I look at their website and the other motor specs, these numbers work out to 5.2 Kw/220 volts/ %28 duty. Does this sound right? If so, is the 220 volt rating going to be a benefit or a curse with 48 volts? Should I go to 72volts??
I also posted this info in a new thread titled "Kostov DC Motor..."

Thanks,
Steve (iggymo)


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## Electric_Rav (Aug 11, 2008)

Any luck with getting that motor to work in a car?


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## iggymo (Apr 17, 2009)

Nope, too small. I did rebuild it, but it just wasn't big enough even for a small car. Found out it is wound kind of different too, will only turn one way unless rewired internally. It is probably about 5 to 7 HP max. I wound up getting a d&d motors 72volt dc series wound motor for the festiva project. Works great, just need better batteries and a chance to transfer all the electricals from the first car to he better one i found. Hopefully soon. I am trying to sell my sidecar motorcycle to fund the new batteries.


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## Electric_Rav (Aug 11, 2008)

I'm wanting to use a 72 volt d&d as well but I want the sepex version. If I were building a electric only I would probably use a series wound but I plan to keep my gas engine because of the distances I drive in a day. If I use sepex I can get regen. Good luck on your project. I would like to see it sometime. Maybe we can start a little club in Sioux falls.


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## Guest (Nov 11, 2010)

You could use 72 volts on that motor with no trouble. It is a Kostov motor for sure. Very robust motor. It could be used in a small low voltage car. Not good for the hwy but a good motor none the less. If you couple a motor to one of the rear wheels you will need a way to disconnect it from the wheel when not in electric only mode because at hwy speeds you will have the danger of over reving the motor in freewheel mode and blow the comms. Not a pretty sight. 

Pete


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