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View Full Version : Testing health of main motor


Naito
06-23-2011, 02:21 PM
Any suggestions for how to do so?

jeffpack1957
06-24-2011, 10:30 AM
other than amp draw under load, I dunno.

NCcraig
06-24-2011, 10:44 AM
Send it to a motor doctor for a check-up. :D

755 robert
06-24-2011, 11:17 AM
This is a good question.The main motor failures I have had caused servo glitches and power shut downs but the motor would still spin up fine with a battery..I think testing amp draw under a load sounds like it might be the way to go..

RedOctobyr
06-24-2011, 12:53 PM
I think the difficult part would getting a consistent test. Full collective at 75% pitch travel is not the same blade angle for everyone, for instance. I'd love to know if there's an answer, though. My motor has gotten louder, and, I think, weaker. Or its just my imagination. I do want to try pulling it, running it in alcohol, then oiling it, to see if that helps. I've seen people say that can help rejuvenate a motor somewhat.

755 robert
06-24-2011, 02:21 PM
I think the difficult part would getting a consistent test. Full collective at 75% pitch travel is not the same blade angle for everyone, for instance. I'd love to know if there's an answer, though. My motor has gotten louder, and, I think, weaker. Or its just my imagination. I do want to try pulling it, running it in alcohol, then oiling it, to see if that helps. I've seen people say that can help rejuvenate a motor somewhat.
I am thinking the only accurate way to test would be with no load and compare with a new motor as a control.

fvdriver
06-24-2011, 02:40 PM
Why don't you measure full neg pitch then put it on a gram scale and see what it reads. The neg pitch # will give you a constant to check against and just use the same type of blades each time.

Naito
06-25-2011, 01:39 AM
Why don't you measure full neg pitch then put it on a gram scale and see what it reads. The neg pitch # will give you a constant to check against and just use the same type of blades each time.

That sounds like a good idea....

I'd love to be able to pinpoint whether the tail is failing due to the main motor drawing too many amps or the tail motor drawing too many amps, right now it's just "replace and test", which is time consuming and expensive.

testing the negative thrust is interesting, but still requires quite a lot of work to replace the main motor. Guess nobody has data on how these motors behave on a bench so we could do some real comparisons?

Skyroo
06-25-2011, 09:11 AM
I regularly run my main motor(after about 50 flights) in a jar of methylated spirit and lube it to prolong its life and I think it has helped heaps. My bench power supply shows it draws about 400mAH current when I feed it with 3.5v while free spinning. My previous failed main motors showed close to 1A fluctuating current draw. The current fluctuation is a sign of worn brushes. Dismantling the motor to clean the armature will only give me a few more good flights so I will not bother next time. My current motor has more flights than I can remember and it is on the way out with the tail blowing out when the battery gets weaker. Time to replace it with a new one.