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Help! Here's a head scratcher...

Arcfyre

Well-known member
#1
So I was flying my TT yesterday with my neighbor. Running an 1808-2400kv motor and a 30 amp cheapo ESC. All was well, and I landed the plane when the timer went off. As I pick it up to carry it back inside, I notice that the ESC is smoking. It got so hot that one of the motor leads melted off.
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I'm no stranger to these garbage speed controllers, I've had them randomly catch fire before. It happens. So I unplug the battery and replace the ESC with the same model, a brand new never before used one. I plug the battery in and the ESC instantly goes up in smoke. Haven't touched the throttle or anything. So that's 2 speed controllers cooked, must be something wrong with the motor.

20190623_091511.jpg

So I get a spare power pod and 15A Skywalker ESC out of my arrow. It has an 1806-2700kv motor on it. This entire unit was pulled out of a working aircraft, no issues whatsoever. I reverse the prop and swap two of the motor leads, put it in the TT and.... Poof! The second I plug in this motor and ESC the magic smoke comes out of the motor this time. The ESC seems fine.

At this point I'm kind of stumped. The only common components now are the RX and the battery. What on Earth could be causing this problem?
 

kilroy07

Well-known member
#2
Could it be a short in the receiver?.... That might overheat the BEC (which I NEVER rely on with these cheap ESCs BTW...)
I have also had just a bad batch of these... Cost me a couple of motors/escs as well... :rolleyes:
The BECs get so hot themselves, sometime it caused a real issue for me... I typically use those cheap buck converters with the 30a Esc. (anything I care more about I get a nicer BEC to use.) :LOL:

I need to make a smoke stopper myself... I wonder if it would have helped here...
 

Arcfyre

Well-known member
#3
Could it be a short in the receiver?.... That might overheat the BEC (which I NEVER rely on with these cheap ESCs BTW...)
I have also had just a bad batch of these... Cost me a couple of motors/escs as well... :rolleyes:
The BECs get so hot themselves, sometime it caused a real issue for me... I typically use those cheap buck converters with the 30a Esc. (anything I care more about I get a nicer BEC to use.) :LOL:

I need to make a smoke stopper myself... I wonder if it would have helped here...
It's either the battery or the RX at this point. I'm just reluctant to hook up another set of gear right now, that's why I came here to get some advice. It's already been a costly day.
 

FDS

Well-known member
#4
The battery can’t cause an overload unless something else is shorting, don’t connect further electronics, pull everything except the servos and work on the bench with a SMOKE STOPPER, then nothing will melt whilst you investigate.
If I get anything that smokes or make any changes to an existing set up I always use my 3A blade fuse smoke stopper. The lightbulb type work too. Mine cost less than $2 to make, has saved me money many times. A smoke stopper would have saved both second and third ESC’s.
 

Hondo76251

Well-known member
#6
"The battery can’t cause an overload unless something else is shorting..."
Time for some investigation for sure!

I'll place my bets on the likely chain of events...
(1) BEC failed, sent full batt voltage downstream
(2)Receiver failed, sent full voltage back through system
(3)Second esc gets hit with full voltage... Poof
(4)Third ESC and motor get hit... Poof

My bet is the Receiver is toast, trouble is, it may have also killed servos. Be sure to check all the electronics...
 

Arcfyre

Well-known member
#7
The battery can’t cause an overload unless something else is shorting, don’t connect further electronics, pull everything except the servos and work on the bench with a SMOKE STOPPER, then nothing will melt whilst you investigate.
If I get anything that smokes or make any changes to an existing set up I always use my 3A blade fuse smoke stopper. The lightbulb type work too. Mine cost less than $2 to make, has saved me money many times. A smoke stopper would have saved both second and third ESC’s.
Good advice, thank you. I've never needed one before today. Looks like I know what today's project is going to be.
 

Arcfyre

Well-known member
#8
Time for some investigation for sure!

I'll place my bets on the likely chain of events...
(1) BEC failed, sent full batt voltage downstream
(2)Receiver failed, sent full voltage back through system
(3)Second esc gets hit with full voltage... Poof
(4)Third ESC and motor get hit... Poof

My bet is the Receiver is toast, trouble is, it may have also killed servos. Be sure to check all the electronics...
Thanks for the advice. Will do some testing and report back.
 

Arcfyre

Well-known member
#9
Ok, I made myself a smoke stopper and assembled the components on the bench to see if i can get a handle on whats going on.

I have the original 1808 motor (black)
A newish, brand name, working 100A ESC out of one of my wings for use as a known good ESC
The power pod assembly from the arrow with a purple 1806 motor and a skywalker 15A ESC. This setup went up in smoke this morning for some unknown reason.

Testing, all done with the new smoke stopper:

1. Black motor with the 100A ESC: System will arm, and the motor will beep after the RX hooks up to the TX. Applying throttle will cause the motor to judder and shake, makes no useable power. After a few seconds of shaking, the motor stops spinning and I get the same original "armed" beeps. SS light is off at all times. Conclusion: motor is bad.

2. Arrow power pack: The second I plug a battery in, the smoke stopper light comes on. Conclusion: WTF I have no idea. This setup has probably 50+ flawless flights on it.
 

Arcfyre

Well-known member
#10
Did a 3rd test with the 100A ESC and a known good motor with the RX out of the TT. The motor spins fine, and all of the servos work. Conclusion: The RX is not the problem either.

At this point I am really at a loss. My RX is testing good, and my "good" power pack is testing bad.
 

Arcfyre

Well-known member
#11
Swapped some more components around using what is known as good and what is faulty.

Both the ESC and motor out of the arrow, when tested individually, are coming back "fail". The motor will spin, but the coils are scorched and it makes almost no power. Im sure it was damaged by a bad ESC. The ESC will not spin the good motor, and when plugged in it triggers the smoke stopper. This ESC likely killed the motor it was attached to, causing this "pack" to go bad. That this pack is bad seems to be a coincidence, as I dont see any way it could be connected to the electronics originally in the TT. Im writing this one off to bad timing.

So this brings me to the original black motor. It was flying just fine, and after I landed, the ESC was smoking. I incorrectly assumed that the ESC had caused the problem, and hooked up a new one. This one also failed almost instantly, leading me to suspect a problem in the motor. Bench testing this motor with a 100A ESC shows that the motor does not spin, and the SS is preventing that ESC from shorting out. RX and servos seems fine when testing, so at the end of the day, im out 3 ESC's and 2 motors for varios reasons. Lousy day. :-(
 

quorneng

Well-known member
#13
Arcfyre
In most electric plane circuits the ESC is the most sensitive component and so acts as a "fuse". I have quite a collection of salvaged ESC heat sinks to prove it!

As you found an ESC blowing does not automatically mean it was faulty but only that something in the electrical circuit was.
Kept within their specification (amps and temperature) an ESC failure is most likely from too many amps flowing, the result of either a physical motor overload or by a wiring short circuit, either in the wires from the ESC to the motor or those inside the motor itself.
An ESC smoking from a manufacturing fault within it is rare by comparison.

Just remember motors and wiring can withstand a considerable (100%+) 'instant' overload but an ESC will not!