Second ESC burned within a minute - Page 2

TMorita · Oct 28, 2009, 08:42 PM

If the Align 60 amp has a linear BEC, then you need to use an external switching BEC.

See section 4.3.3 in the EHBG for more info here:

http://www.swashplate.co.uk/ehbg-v18/ch04s03.html

Toshi

bb42 · Oct 30, 2009, 01:04 PM

Quote:

Originally Posted by arbilab

Whuddeye say in the second frame, about eating ESCs? And the 4th frame, about 3A? OK, 'nuff toldyaso.

Sorry, arbilab, I'm not a native english speaker so I don't understand precisely what you're saying. If there is a feeling that I don't trust your expertise it's wrong - it was mainly your remarks that made me go for another motor instead of a bigger ESC (only).

Quote:

Magnet may have cracked, introducing more poles than were supposed to be there. Still "runs" but nowhere like it was designed to.

Just disassembled the motor, the magnets in the cap show no sign of cracks.
Anyway, this could merely be the explanation for the low 'latch force'.
So if it's not the magnets that are faulty, how about the stator coil parts?:
http://en.wikipedia.org/wiki/Electrical_steel

arbilab · Oct 30, 2009, 01:41 PM

Sorry BB, I was quietly gloating about being right, without specifically knowing a great deal about heli brushless. Nevermind that.

Not sure you could see a magnet crack that would produce an additional pole where there wasn't supposed to be one. But that would account for not feeling the cogging you would expect. It would also generate spurious (asynchronous) CEMF that the ESC couldn't anticipate.

I can't assert that the core/stator metallic properties did NOT change, but it would be the last place I'd look (not being a metallurgist).

Coil properties (such as inter-winding insulation breakdown) would not be evident rotating by hand and sensing cogging. Not likely (though not impossible) anyway, in the absence of thermal discoloration.

bb42 · Oct 30, 2009, 03:27 PM

I'd rather believe the stator metals were of inadequate property / quality in this batch of motors, not that they changed.
"Absence of thermal discoloration" - confirmed.

arbilab · Oct 30, 2009, 04:00 PM

Stator metal properties are electromagnetic. They are still lumps of steel from a purely magnetic perspective, and could not affect what you feel as cogging.

It's all but moot, as the motor was defective one way or the other.

bb42 · Nov 02, 2009, 07:27 AM

Quote:

Originally Posted by arbilab

Stator metal ... are still lumps of steel from a purely magnetic perspective, and could not affect what you feel as cogging.

Okay.

Quote:

It's all but moot, as the motor was defective one way or the other.

I'd be happy to identify a way to test motors for this kind of faults, that are not easy to detect but can cost considerable time and money. Might be of increasing interest to the community as well, as BL motors will become more widespread and quality assurance can merely be expected to improve much on the side of the manufacturers.

arbilab · Nov 02, 2009, 02:51 PM

I think you empirically discovered one way to test them. Bad ones don't cog right.

aerorotor · Nov 03, 2009, 11:06 AM

All it takes is a the assembler to be lazy and not put enough magnets in or have a few magnets with the wrong poles facing in.

Glad you tried a new motor, when I started reading this thread all I could think of was what Einstein said "To do the same thing over and over and expect different results is the definition of insanity."

bb42 · Nov 05, 2009, 09:07 AM

- "Bad ones don't cog right." Only how strong the cogging should be for a "right" motor vs one that will eat your hardware remains open .. if one does not happen to have both of them to compare; which will be rare.

- "not put enough magnets" - no, I opened the motor, everything looks fine.
- "magnets with the wrong poles facing in" sounds interesting, I'll test this one of these days.

arbilab · Nov 05, 2009, 12:28 PM

Yes, "cog right" varies by design, you'd have to have a good one to compare it to. We're not sure that was the issue either, just a suspect. But a healthy PM motor of any appreciable size is going to cog, and you noticed this one didn't (very much).

going4speed · Nov 05, 2009, 01:01 PM

I had this type of trouble with a motor. Turns out one of my solder connections was not good even though it looked find it turned out to be a cold solder connection at the bullet.

Quote:

Originally Posted by bb42

My SJM400 just burned it's second brushless ESC controller - the first (Otter BS35A) lasted a couple of short (1 min.) hover flights after which the ESC cut down, seemingly due to overheat. Before it was neccessary to change to "hard timing mode", otherwise the motor would stop beyond half throttle. The current I measured was max. 13 A (w/o the blades attached).
The last flight then left the Otter ESC with dark smoke...

Then I got another ESC from Pulsar (a rebranded Hobbywing) with 25A. Here I took off the plastic coating to feel the warming up in test runs. It turned out that the ESC gets quickly hot after pushing the throttle over a certain level - similar to the Otter ESC before I changed to "hard timing". So I changed this timing to "high" - and the ESC sent smoke signals on the first test run.

Folks, what's wrong here? Is there some issue with the motor that it burns one ESC after the other? Are there not any (a bit more) intelligent ESCs that sense what the motor is doing instead of sending smoke? Or do I need a more powerful ESC (this is a 400 heli, definitely smaller than a 450)?

bb42 · Nov 06, 2009, 07:55 AM

Quote:

Originally Posted by going4speed

I had this type of trouble with a motor. ...

Sorry, but reading this thread should make clear that you had a completely different technical problem.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
ESC burned up	Hap02	Power Systems	4	Jan 08, 2004 02:43 PM
Fusion esc burned up?	ProfitOfDoom	Electric Heli Talk	3	Oct 13, 2003 11:53 AM
6 amp Esc burned in stock GWS Beaver	Wheazel	Power Systems	2	Jul 13, 2003 12:07 AM
Using a second ESC to control lights etc. ?	Bill Glover	Electric Plane Talk	8	Sep 26, 2002 01:27 PM
GWS esc burned out: repair question...	burgan	Power Systems	1	Jul 15, 2002 11:16 PM

Oct 28, 2009, 08:42 PM	#16
TMorita Registered User Join Date: May 2002 Location: San Carlos, California, United States Posts: 7,513	If the Align 60 amp has a linear BEC, then you need to use an external switching BEC. See section 4.3.3 in the EHBG for more info here: http://www.swashplate.co.uk/ehbg-v18/ch04s03.html Toshi

Oct 30, 2009, 01:41 PM	#18
arbilab Unemployed Engineer Join Date: Jan 2009 Location: DFW, TX Posts: 3,329	Sorry BB, I was quietly gloating about being right, without specifically knowing a great deal about heli brushless. Nevermind that. Not sure you could see a magnet crack that would produce an additional pole where there wasn't supposed to be one. But that would account for not feeling the cogging you would expect. It would also generate spurious (asynchronous) CEMF that the ESC couldn't anticipate. I can't assert that the core/stator metallic properties did NOT change, but it would be the last place I'd look (not being a metallurgist). Coil properties (such as inter-winding insulation breakdown) would not be evident rotating by hand and sensing cogging. Not likely (though not impossible) anyway, in the absence of thermal discoloration.

Oct 30, 2009, 03:27 PM	#19
bb42 Registered User Join Date: Oct 2009 Location: Berlin Posts: 10	I'd rather believe the stator metals were of inadequate property / quality in this batch of motors, not that they changed. "Absence of thermal discoloration" - confirmed.

Oct 30, 2009, 04:00 PM	#20
arbilab Unemployed Engineer Join Date: Jan 2009 Location: DFW, TX Posts: 3,329	Stator metal properties are electromagnetic. They are still lumps of steel from a purely magnetic perspective, and could not affect what you feel as cogging. It's all but moot, as the motor was defective one way or the other.

Nov 02, 2009, 02:51 PM	#22
arbilab Unemployed Engineer Join Date: Jan 2009 Location: DFW, TX Posts: 3,329	I think you empirically discovered one way to test them. Bad ones don't cog right.

Nov 03, 2009, 11:06 AM	#23
aerorotor Registered User Join Date: Oct 2009 Posts: 67	All it takes is a the assembler to be lazy and not put enough magnets in or have a few magnets with the wrong poles facing in. Glad you tried a new motor, when I started reading this thread all I could think of was what Einstein said "To do the same thing over and over and expect different results is the definition of insanity."

Nov 05, 2009, 09:07 AM	#24
bb42 Registered User Join Date: Oct 2009 Location: Berlin Posts: 10	- "Bad ones don't cog right." Only how strong the cogging should be for a "right" motor vs one that will eat your hardware remains open .. if one does not happen to have both of them to compare; which will be rare. - "not put enough magnets" - no, I opened the motor, everything looks fine. - "magnets with the wrong poles facing in" sounds interesting, I'll test this one of these days.

Nov 05, 2009, 12:28 PM	#25
arbilab Unemployed Engineer Join Date: Jan 2009 Location: DFW, TX Posts: 3,329	Yes, "cog right" varies by design, you'd have to have a good one to compare it to. We're not sure that was the issue either, just a suspect. But a healthy PM motor of any appreciable size is going to cog, and you noticed this one didn't (very much).