can bl motor be fried by 2 of the 3 motor wires touching - RC Groups
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Jan 29, 2012, 07:16 PM
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can bl motor be fried by 2 of the 3 motor wires touching

Ok, so I was running this motor and it was running fine. Then it stopped working after about 10 mins. I looked at it and saw 2 of the motor wires were touching each other. One of the bullet connectors had a slight burn mark where they were touching.I can't get the motor to work now. I popped off the end cap where the motor wires go in to give it a quick glance. I don't see any windings broke or the leads from the motor wires broken either. Any ideas?
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Jan 29, 2012, 07:48 PM
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Lnagel's Avatar
The most likely result of the short circuit is that the motor is ok but the ESC is ruined.

Jan 29, 2012, 08:04 PM
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flydiver's Avatar
You created a short circuit.
With a short circuit of any length of time under power will fry the ESC.
Motor is likely OK but if it won't run IMMEDIATELY and CORRECTLY on a new ESC then it may have a problem too.
Jan 29, 2012, 08:15 PM
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Hrm. So Im not sure whats going on here. I sprayed some wd-40 down into the can and let it dry out then put motor back together. I then kind of jurry riged it up to a different esc I've got and try to get it to run. It kind of clicked for a second. I then hooked it back up to the original esc. I was giving it throttle and nothing. Then all of the sudden it just jerked on and started working. Seconds later smoke is coming out the esc, but its still running. So I unhook the battery and wait a few minutes. Hook it back up and esc starts up fine, lets me control servos etc. Hook up the motor and it starts up right away but then smoke comes out the esc again. If the esc wasn't fried before I'm sure it is now. Just hope I don't gotta buy a new motor and speed control now. Sigh. Anyway to take apart the esc and see if its somethign fixable. Ok well after taking apart esc there is 3 square black chips that have burned. Anyway to replace these.
Last edited by stingeragents; Jan 29, 2012 at 08:31 PM.
Jan 29, 2012, 09:22 PM
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flydiver's Avatar
Originally Posted by stingeragents
Sigh. Anyway to take apart the esc and see if its somethign fixable. Ok well after taking apart esc there is 3 square black chips that have burned. Anyway to replace these.
Those are the FETS, If you gotta can't. Buy a new one.

If the motor wouldn't run on a new ESC, it's likely fried too. As I said, brushless motors should run IMMEDIATELY and CORRECTLY.
If they don't, STOP....NOW!!!! ..... or your fry your ESC.

A bad ESC will not likely fry a motor but a bad motor WILL fry an ESC if you keep power to it....guaranteed.
The ESC controls the running of the 3-phase motor. If any one of the phases is bad the ESC can't do it's job. The motor either won't run, jerking erratically is VERY common, or strange behavior. This is a DEAD SHORT condition and cooks those little chips.
Jan 29, 2012, 09:54 PM
Registered User
I ALWAYS test new batteries, motors & ESC as soon as they arrive. Easier to get the company to replace them.
Hook up the Motor & ESC use about a 1000 mahr battery. no prop. Clamp the motor gently in something to prevent it from rolling around & shorting the motor leads.

ONLY move the transmitter speed lever to about 20%. Quick move to 20% & back to 0 %.
1 second is more than enough to test any part for the first time. next. move the throttle to 30 or 40 % & back to 0%. Good ?? OK try the rest of the new motors & ESCs.

If ANY part does NOT work as expected.... STOP..STOP do not test that part anymore times !! You are straining the other parts. ASK for a replacement.

Jan 29, 2012, 09:55 PM
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LoL. I spent the last like hour trying to figure out what they are called and then bam you let me know. I do know how to solder quite well. Not super familiar with pcb's but if I could figure out where to buy one im sure I could do it. Anyways, I put the esc back together. Hooked everything back up and it all seems to work with no smoking. Took my truck outside and drove it around for about 5 minutes. There is a bit of cogging now down low that wasn't there before but other than that it worked as it should. Didn't smoke, and the motor didn't overheat. I'm upset I didn't do some tests before hand cause now I'm not sure what went bad first. I honestly think something with the motor got jacked up. I think the sudden jerk of it starting fried that chip. It all seems to be working now though so guess I'll keep it rolling until something burns out for good. LOL. Just realized this is an aircraft forum. Oh well, same principle. I fly airplanes too. I never fried anything when I've touched airplane motor wires before. It wouldn't even run right at all. Would kind of stutter immediately so I knew something was wrong. This thing ran fine for a good 10 mins. Ok just did some research on how to remove and replace mosfets, but not sure how to figure out what voltage one I need.
Last edited by stingeragents; Jan 29, 2012 at 10:05 PM.
Jan 30, 2012, 08:28 AM
Registered User
Sounds like your ground vehicles CAN get something sticking in the drive train somewhere. You may have got off very lucky. Planes USUALLY do not have that dirt problem.

You are right to always expect the motor, gearbox or ESC to act up again.

Good luck with the repairs. Go to the Electronic D I Y section. Most of them are pretty good at repairing your problem.

Personally. I would just run the vehicle till it dies. Then, DO NOT reuse either the ESC or the MOTOR. Not worth the survivor causing another new part to smoke for no reason again.


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