Rimfire 1.60 windings damaged? - RC Groups
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Oct 22, 2017, 10:30 PM
Registered User
Discussion

Rimfire 1.60 windings damaged?


I hope the windings and the discoloration can be seen. Are the windings damaged? I don't know the history of this motor. I just bought it. Your inputs are most welcomed.
Last edited by truevine77; Oct 27, 2017 at 01:36 AM. Reason: spelling
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Oct 23, 2017, 01:57 AM
I am a nice guy! Really!
I am inclined to say no, the windings next to the discoloration look perfect. My impression is that the motor was run through a cow pasture and got the worst of it.
Oct 23, 2017, 08:34 PM
Registered User
Quote:
Originally Posted by Mike Dubovsky
I am inclined to say no, the windings next to the discoloration look perfect. My impression is that the motor was run through a cow pasture and got the worst of it.
Thanks for your response
Oct 24, 2017, 12:35 AM
Electric RC Addict
Looks fine to me. If those windings were really dark in color, I'm talking almost black, then I would start to worry.

I suppose you could also try the sniff test. If something smells burnt, then I would also start to worry.
Oct 24, 2017, 02:23 AM
Registered User
Skylar's Avatar
Quote:
Originally Posted by truevine77
I hope the windings and the discoloration can be seen.

Have you tested the motor leads for continuity? Even better would be to measure the resistance of the phases.



@Mike: That was hilarious
Oct 24, 2017, 03:30 AM
Registered User
AntiArf's Avatar
Quote:
Originally Posted by Mike Dubovsky
I am inclined to say no, the windings next to the discoloration look perfect. My impression is that the motor was run through a cow pasture and got the worst of it.
Similar thoughts. It seemed odd that the area of the windings that should cool well, are where the "effects" seems to be. Almost as if some compound (maybe bovine related?) came in contact with the insulation. Probably would have been best if the person who offered this motor to you had been clear about it though. Hobbyists are particular about things that look questionable, and I would question it also, even if it does run fine. I would measure the phases as Skylar suggested.
Oct 24, 2017, 12:44 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
I would clean of the gunk for better cooling of the coils.

Vriendelijke groeten Ron
Oct 24, 2017, 07:43 PM
Registered User
vollrathd's Avatar
Quote:
Originally Posted by DBJr
Looks fine to me. If those windings were really dark in color, I'm talking almost black, then I would start to worry.

I suppose you could also try the sniff test. If something smells burnt, then I would also start to worry.
Burned windings have a very distinctive smell. From one that has smelled more than a few of them.
Oct 24, 2017, 08:31 PM
Electric RC Addict
Quote:
Originally Posted by vollrathd
Burned windings have a very distinctive smell. From one that has smelled more than a few of them.
Me too. It is nasty.

ESC smoke isn't much better either.
Oct 25, 2017, 02:03 PM
Jack
jackerbes's Avatar
Here is a quick and simple test you can do with almost any DMM, if the readings on all three motor connector pairs is not about the same you have shorted windings or shorted to the stator windings.

Jack

You are putting your ESC at risk of damage by pressing on with more throttle and longer duration when a motor will not start and/or run normally when you open the throttle one or two clicks (this assumes the ESC has armed itself normally and is ready to use).

If you have one, you can do some simple checks with a digital multimeter (DMM).

With a DMM set to R x 1 you should see the same low resistance on all three connector pairs (1-2, 1-3, 2-3). It should be a very similar low value, usually less than a few Ohms, and it should be steady and not flickering. That will tell you that you have continuity and separation on all three phases. If all three are about the same and have steady readings the windings are intact from the bullet connectors and through the windings.

A second check would be to check for a shorted winding. If the motor is a CD-ROM style motor or if the magnet housing is off (or through cooling openings), find two spots on the stator where you can get continuity between the two probes. The ends of the stator arms (where the magnets pass by them) are usually a good spot and you might have to scratch through a coating.

When you have continuity on the two probes, remove one probe and touch each of the three motor connectors. The meter should read open from the stator to all three connectors. If there is any flickering or steady resistance values seen, you have a winding that is shorted to the stator.
Oct 27, 2017, 01:40 AM
Registered User
Happy to report that there is no burnt smell. I need to get a DMM to test the phases. Thanks a lot for your input guys. What would be recommended to clean off the windings?
Oct 27, 2017, 08:25 AM
Jack
jackerbes's Avatar
Quote:
Originally Posted by truevine77
Happy to report that there is no burnt smell. I need to get a DMM to test the phases. Thanks a lot for your input guys. What would be recommended to clean off the windings?
Outrunner Disassembly and Stripping - www.rcgroups.com/forums/showthread.php?t=1823636

How to repair an electric motor - www.rcgroups.com/forums/showthread.php?t=1079423

Shaft repair or replacement

Making and Replacing a Brushless Motor Shaft - http://www.rcgroups.com/forums/showthread.php?t=1240725

A toothbrush and some alcohol or paint thinner should work and not damage the insulation on the wire.

Go online and sign up to get the Harbor Freight flyers in the mail, you'll get one every week and it will have things that are free with any purchase. One of the things they give away regularly is a DMM...

I have five or six of them now...

Jack
Oct 27, 2017, 09:36 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Quote:
Originally Posted by truevine77
... What would be recommended to clean off the windings?
Toothbrush, fingernail, broken prop?


Several simple motor tests
  1. Opening an outrunner for visual inspection
  2. Drytesting brushless motors - WFF (RCG user vollrathd)
  3. Generator test I, only using a power drill and a voltmeter
    (Re)winding and building motors - RCG (sticky) → opening post → #40 Generator test
  4. Generator test II, quick&crude, using a second brushless motor and powerdrill
    Three Phase Alternator - Three Phase Motor? - RCG
  5. Overheated magnets result in lower magnet strength (irreversible! ), which in turn results in higher Kv. Motorcurrent is proportional to Kv cubed
    Higher current → hotter motor → weaker magnets → higher Kv → higher current → hotter motor → weaker magnets → higher Kv → higher current ⟲⟲⟲ etcetera etcetera, temperature runaway
  6. Determining whether magnets still have original strength, by determining whether Kv motor parameter (in rpm/volt) is still the same, several simple straightforward methods.
    www.bavaria-direct.co.za → motor constants
Prettig weekend Ron
Oct 30, 2017, 08:33 PM
Registered User
Quote:
Originally Posted by Ron van Sommeren
Toothbrush, fingernail, broken prop?


Several simple motor tests
  1. Opening an outrunner for visual inspection
  2. Drytesting brushless motors - WFF (RCG user vollrathd)
  3. Generator test I, only using a power drill and a voltmeter
    (Re)winding and building motors - RCG (sticky) → opening post → #40 Generator test
  4. Generator test II, quick&crude, using a second brushless motor and powerdrill
    Three Phase Alternator - Three Phase Motor? - RCG
  5. Overheated magnets result in lower magnet strength (irreversible! ), which in turn results in higher Kv. Motorcurrent is proportional to Kv cubed
    Higher current → hotter motor → weaker magnets → higher Kv → higher current → hotter motor → weaker magnets → higher Kv → higher current ⟲⟲⟲ etcetera etcetera, temperature runaway
  6. Determining whether magnets still have original strength, by determining whether Kv motor parameter (in rpm/volt) is still the same, several simple straightforward methods.
    www.bavaria-direct.co.za → motor constants
Prettig weekend Ron
Thanks,

Ron


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