Welcome to FPVDronePilots!
Join our free FPV drone community today!
Sign up

Smoking esc....

baevans11

Well-Known Member
Joined
Aug 3, 2017
Messages
206
Reaction score
93
Age
41
I'm building a brushless whoop with a teeny 1s stack and I have everything wired up and I'm pretty sure it's all correct. But when I go to power it on the esc starts to smoke at the negative lipo lead and multiple motor pads. It starts cooking the excess resin from soldering. Any idea what could be wrong? I checked to make sure nothing was soldered together. Is there some way I can diagnose this other than pulling the whole thing apart and waiting things up one by one till I find the problem? Thx for any help!
 
Smoke is never good...
2 things can cause smoke, frying components or heat.
If it is frying components its life will be very short, if it is heat then the solder joints are creating heat and that isn't good either.
Are you using 37/63 Eutectic solder? If not it could be cold solder joints. I would check how many Ohm of resistance between positive and negative battery connection to get an idea of if there is some kind of high resistance short or something wrong with the wiring.
 
Smoke is never good...
2 things can cause smoke, frying components or heat.
If it is frying components its life will be very short, if it is heat then the solder joints are creating heat and that isn't good either.
Are you using 37/63 Eutectic solder? If not it could be cold solder joints. I would check how many Ohm of resistance between positive and negative battery connection to get an idea of if there is some kind of high resistance short or something wrong with the wiring.
Sorry for the slow response and thank you for answering my post. I'm using 60/40 tin/lead rosin core solder. Checking the resistance between + & - solder joints on the main lipo lead I got a reading of 10.8 k ohms. Thoughts? Would cold solder joints cause heat to the point where the excess rosin would start melting? Also what other ways do you recommend that I can start narrowing this problem down. Thanks again!
 
  • Like
Reactions: HighTechPauper
The great thing about 63/37 is that is does not have a plastic state, it goes from liquid to solid instantly so there is no real chance of a cold solder joint.

10.8 K ohms is definitely NOT a short, and yes a cold solder joint can be so bad that it causes that much heat, but I think you have done enough of this kind of work that I doubt that is the issue.

The first suggestion is to clean the old flux/rosin residue off the board with alcohol and an old toothbrush, flake the big chunks off first with a plastic tool or toothpick since that will make cleaning a lot easier. If you use some paper towels to isolate what you want to clean from things you don't want the solvent to touch is a good idea too. Don't let any near your camera lens and preferably put the lens cap on to make sure it doesn't.

Then I would recheck your resistance reading and if it is still that high (10 K ohms) I think there may not be a problem at all, and the circuitry heating up for the first time may be enough to cause all your concern. If it is a 1s lipo then the USB connection is actually a higher voltage, does the FC connect to betaflight and check out ok?
 
The great thing about 63/37 is that is does not have a plastic state, it goes from liquid to solid instantly so there is no real chance of a cold solder joint.

10.8 K ohms is definitely NOT a short, and yes a cold solder joint can be so bad that it causes that much heat, but I think you have done enough of this kind of work that I doubt that is the issue.

The first suggestion is to clean the old flux/rosin residue off the board with alcohol and an old toothbrush, flake the big chunks off first with a plastic tool or toothpick since that will make cleaning a lot easier. If you use some paper towels to isolate what you want to clean from things you don't want the solvent to touch is a good idea too. Don't let any near your camera lens and preferably put the lens cap on to make sure it doesn't.

Then I would recheck your resistance reading and if it is still that high (10 K ohms) I think there may not be a problem at all, and the circuitry heating up for the first time may be enough to cause all your concern. If it is a 1s lipo then the USB connection is actually a higher voltage, does the FC connect to betaflight and check out ok?
Ok great thank you for all your help again! I will do as you recommended. Just to be clear the solder components are the same its merely the ratio that causes the different solidification you stated? Also are there any brands of solder that you prefer and have noticed a real difference in quality in? Thanks again!
 
That is correct, it is simply a different ratio of tin to lead, and it has 2 great properties ideal for electronics, the lowest melting point 361F vs 370F and no plastic state (also called a pasty state). I still have 20+ year old solder rolls from my working days so I won't be buying solder anytime soon, but Kester makes some of the best out there. Try not to be too shocked at the cost of a good 63/37 Rosin core solder, it can go from $20-$40 for a 1 pound roll, and beware cheaper options since they have much higher impurities in them and that makes it tough to use and a poor final product. This is what I would order if I needed to.

 
  • Like
Reactions: baevans11
That is correct, it is simply a different ratio of tin to lead, and it has 2 great properties ideal for electronics, the lowest melting point 361F vs 370F and no plastic state (also called a pasty state). I still have 20+ year old solder rolls from my working days so I won't be buying solder anytime soon, but Kester makes some of the best out there. Try not to be too shocked at the cost of a good 63/37 Rosin core solder, it can go from $20-$40 for a 1 pound roll, and beware cheaper options since they have much higher impurities in them and that makes it tough to use and a poor final product. This is what I would order if I needed to.

Thank you very much for all your help and advice! I'll post back when I've had time to address things.
 
  • Like
Reactions: HighTechPauper
That is correct, it is simply a different ratio of tin to lead, and it has 2 great properties ideal for electronics, the lowest melting point 361F vs 370F and no plastic state (also called a pasty state). I still have 20+ year old solder rolls from my working days so I won't be buying solder anytime soon, but Kester makes some of the best out there. Try not to be too shocked at the cost of a good 63/37 Rosin core solder, it can go from $20-$40 for a 1 pound roll, and beware cheaper options since they have much higher impurities in them and that makes it tough to use and a poor final product. This is what I would order if I needed to.

I got an update. Well I pulled all the solder off the esc and cleaned it real well. Then using new 63/37 MG Chemicals brand I re soldered all the motor wires and lipo pigtail back on to the board. Then plugged in the lipo and voila! Everything seems to be in order. I dont know if it was a cold joint or a small piece of solder creating a bridge somewhere but at least the problem is solved. Thanks so much for all the help! Hopefully I dont have any more issues on this build lol.
 

Members online

No members online now.

Forum statistics

Threads
6,011
Messages
44,354
Members
5,307
Latest member
Kodax