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Jun 05, 2010, 12:46 AM
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Discussion

Fried mystery esc


Hey, I have recently built my first plane, a blu baby, and when buying the electronics, bought a mystery 30a esc + motor. Long story short I used a overly large propellor and the esc started to smoke. I have ordered another of the mystery brand (the only cheap one I can find that gives propper specs), and before i try it:

1. The screws on the motor may have possible dug into the coil, is it possible that the new esc could be fryed just by a short in the motor?(unlikely in my oppinion, its brushless, and i doubt that this would cause it to surge) or generally by the motor?

2. Is mystery a generally reliable brand? I know people have trouble programming them, I did but worked it out, but do they perform propperly?

Cheers!
Jack Allison
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Jun 05, 2010, 02:20 AM
Registered User
Have you ordered a smaller propellor too? And a wattmeter? With any new setup, you really need to measure the actual current, and swap your prop if necessary to keep the amps as high as possible while staying within the motor specs. Your ESC should ideally be rated for about 20% more than the motor.

If the motor screws have shorted a winding, that could certainly cause the death of the ESC. If the screws just scratched the surface of the winding, and have since been replaced with shorter screws that don't touch, the motor may be okay still. But running the motor with the screws touching has probably caused damage to the windings.
Jun 05, 2010, 03:55 AM
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I have a much smaller propellor, 4 inch instead of 6, dont ask me anything else about it. Thanks for your help with the windings, I will check this.

More suggetions are very welcome.

Cheers!
Jack Allison
Jun 05, 2010, 06:12 AM
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Quote:
Originally Posted by Jhackulon
I have a much smaller propellor, 4 inch instead of 6, dont ask me anything else about it. ...
I won't ask you anything else about it

But, since you seem to be not sure what you have, I will point out that, all else being equal, it's the battery volts and the prop size that determine how many amps will go through the motor and ESC when you open the throttle fully.

Reducing the prop diameter and/or pitch will reduce the number of amps; too small prop size and you might not get the power that you need. That's why I suggest you get a wattmeter, so you can check what amps you've actually got

As for the motor windings, by the way, you can get a fair idea if they're okay by using a DVM to measure ohms: Check between each of the three wires in turn (e.g. red-to-black, black-to-yellow, yellow-to-red) and you should get the same low ohms reading -- I don't know what ohms it should be, but it should be practically the same in each case. Then check between each of the three wires and the case or shaft of the motor (anywhere you can find bare metal) and you should see open-circuit each time.
Jun 05, 2010, 10:24 AM
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Dr Kiwi's Avatar
1. The screws on the motor may have possible dug into the coil, is it possible that the new esc could be fryed just by a short in the motor?(unlikely in my oppinion, its brushless, and i doubt that this would cause it to surge) or generally by the motor?

Just FYI: if you read the MegamotorUSA information it says something like this "the most common cause of motor failure is mount screws which are too long". Yes, touching the windings with a mount screw can certainly fry both motor and ESC... I've done it!
Jun 05, 2010, 06:12 PM
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Thanks guys, your posts have been really helpfull!

Cheers!
Jack Allison
Jun 05, 2010, 06:24 PM
Electric Hippy
I really like the mysteries in my heli's. going to try one in a plane soon.
Jun 05, 2010, 07:03 PM
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after testing with my multimeter i got .6, .5, and .5.
can someone please tell me what this means.

Cheers!
Jack Allison
Last edited by Jhackulon; Jun 05, 2010 at 09:57 PM. Reason: retested after posting (was .6, .6, .5)
Jun 06, 2010, 01:51 AM
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these results seem pretty standard, should i go ahead and use the motor?


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