ESC started smoking, need help to understand why!

I have this ESC ( that did an annoying and loud beeping sound on startup. Because the sound is made by the motor my idea was to disconnect the motor for the first few seconds of the startup and then connect it again.

So I disconnect the first cable from the motor and then switch the board on, but the motor still beeps. So I disconnect another cable from the motor and this time I hear a spark from the point where one of the power cable is connected to the switch. To avoid other problems I reconnect the two cables and switch the board on (this is now the usual setup) but, even if the ESC turns on, when it should starts beeping it somehow “restarts” (there was maybe a short circuit).

Now I think that maybe the switch has been damaged, so I remove it and switch the board on directly connecting one of the power cables to the battery (something I did also when my previous switch was broken), and at this point the ESC starts smoking from the inside.

I later opened the ESC and noticed that one of the internal capacitors (there’s also an external one) was disconnected (not welded anymore), as well as some burning marks.

My questions: -what the heck happened to the ESC? It has worked just fine so far -is it possible that the main cause is giving power to the ESC without it being completely connected to the motor? -is any of my actions the cause of the failure? -the capacitor disconnected because of the heat that caused the smoke or its disconnection is the cause of the failure? -should I buy the same esc again? (I don’t think so)

Any suggestion will be greatly appreciated; thank you in advance! :upside_down_face:

Well, probably the power button was broken, but now you fried the esc by connecting it to the battery directly.

Actually the switch still works, and I don’t think I’ve fried the esc by connecting it directly to the battery as it’s something I had done previously (and there’s no difference in connecting the esc to the battery with a switch or with a connector). Do you think the problem was powering the esc with it being only partially connected to the motor? Or the fault is only of a crappy esc?

A spark from plugging it in could have fried it. That’s why I always use Xt90S connectors with the antispark capability.

could it be that the two disconnected leads accidentally touched each other causing the spark while you turned your ESC on?

…mhhhh magic smoke. probably the aftermath of the big spark?

sounds like you accidentally shorted the disconnected leads when powering up. i´m no engineer so i cannot give you any other explanations. The ESC vibrates the motor to produce the accoustic signal you described - thats “normal” - i used a car ESC on my first build…it used to annoy me too…

Capacitors are also sensitive to over-voltage…mabe the voltage was more than the capacitors could handle? (could be an underrated capacitor that finally quit)

nope. save a few more bucks and get a VESC. (no, I´m not affiliated to any seller :smile:)

Don’t think so, but can’t be sure about that.

The voltage should have been normal; my ipothesis is that the capacitor disconnected for some reason and that caused the esc to fail.

Thank you for your suggestion. What is the main difference between an esc and a vesc? Do you suggest any specific one?

Thank you, I’ll consider using thos connectors in the future.

if youre looking for a good cheap vesc ive been seeing good reviews for the flipsky 50a ones, or even the dual if you have 2 motors

otherwise you could get a pair of focboxes, get a thermal case for them and youll probably have more power than you will ever want

i can only recommend the hobbyking VESC since its the only one i used so far. so far it has been doing its job well until a capacitor failed (pins broke off) due to occuring vibrations. easy repair…no problem

a VESC has good acceleration curves , good brakes and regenerative braking. its really the better option compared to a car ESC. another plus is if you want to increase voltage,you can go up to 10S - 12S (though 12S is maybe hard at the limits and you risk frying your VESC).

1 Like

Thank you very much! Are you talking about this one?

yes that one.

1 Like

Nope. The biggest danger with that spark is wearing out the connector. This will never burn out an ESC.

@Mau Reasons it may have blown: Faulty ESC. You could have had a faulty capacitor in your ESC that just went out as you plugged it directly into the battery.

Shorting motor. The more likely scenario is that you somehow shorted the motor wires when you turned the ESC on without the motor plugged in. You should have never done this. Most ESCs need to see the motor to go through their proper boot up and syncing. Taking one or two leads out essentially tells the esc theres a faulty motor and it can fail catastrophically if the ESC doesn’t expect it or know what to do with the condition.

The issue definitely did not come from connecting the battery directly to the esc. Not how things work


Not sure that the beeping is the motor dude. Car esc’s beep on boot up to let you know they’re on.
They all do it. Its normal. The beeps usually let you know if there is an issue. It beeps to tell you the amount of cells connected. If it doesn’t beep properly you have a problem. Read the manual.

Thank you. I’m gonna buy a better esc and, most importantly, never try this again!

The beeping was absolutely normal, and I could feel it was made by the motor (because of the signals sent from the esc) by touching it. I just didn’t want it to beep.

@Mau Yes, please just buy a vesc 6.x. The biggest issue I had with this esc in particular (I’ve used multiple of them, the 150a one is much better) is the settings are terrible. Instead of being able to limit current to a finite number, you have settings like low, medium, and high, with no way of knowing what real world numbers those correlate to. So it’s easy to over work these little guys and blow them up. I also had these 120a guys smoke and blow up. The second one I used made my motor smoke and overheat too. It’s nightmare not being able to do some simple math to set it up correctly and instead, rely on trial and error, with error meaning time to buy another esc.

“good” and “cheap” are mutually-exclusive. You pick one or the other. Your choice.

I’ve never used this ESC before but my suspicion is that the beeping is coming from the motor, because it might be doing some sort of motor autodetection on bootup, and the rotor might be making that noise as the ESC is probing the windings to measure resistance, inductance, et cetera

1 Like

Thanks for your reply, do you think that the hobbyking vesc is a good choice? (

fine fine, “good, for being cheap” would have been a better way to phrase it

1 Like