After emailing back and forth with Alex I still can’t figure it out. So I open this topic.
This summer I built myself a 4WD board on 20s with stormcores 100D and maytech 6374 90KV.
After several rides (125km), the board suddenly wouldn’t start from a standstill on a ride. (metr logs showed no fault and motor temps below 50degrees). The only solution was to switch the board on and off several times. After I did that, the right rear engine stopped working. After further inspections, one of the windings turned out to be burnt. Motor never went above 50degrees.
I assumed this was a manufacturing error. Without any problem I ordered a new one and installed it.
Now after again 100km the right rear motor burned again. I had just left home. After 1km of driving I wanted to leave from a traffic light. 3 motors were spinning but the rear right was on full brake and couldn’t turn. When I felt this I immediately released the throttle but I clearly saw smoke coming from this motor. I checked immediately the meter but each motor was at 40 degrees and I could easy hold the motor, The can was not hot at all. Only the winding itself is burned
In the meantime that the motor broke what I obviously driven on a 3WD. Currently these 3 motors have already done more than 500 km.
I believe in coincidence, but this is suddenly a lot of coincidence. Both motors are from a different batch. A little probability calculation makes this chance quite exceptional. Especially if you take into account that
the motors are operated under the recommended current (motor amps on 50A)
the motors are loaded much less than a 2 wheel drive board
the metr logs currently show that the motors have never seen more than 40A each.
I’ve always learned that a motor is a pretty “dumb” part that can take a lot of abuse.
I expect that controlling the mosfets based on the timing has been programmed incorrectly.
I assume that at that moment a large short-circuit current is sent through two motor wires, causing the winding to burn out.
I think if enough current is passed to short the motor it would also ruin the esc. I bet it’s just the motors. Maybe u can dissect the winding and see a possible short location against the case
Would do this. Also you can actually rewind the fried winding with fresh copper and check if it maybe happens again. Some copper wire is a lot cheaper the a whole motor. You just need to measure the gauge and count the windings.
That winding is cooked and even if there’s no short within the winding, which it doesn’t look like and seems a whole phase shorted, the insulation is burnt toast n won’t be long till shorts again if even possible to wind with such cooked stuff.
Can you locate where the windings started to burn our? Maybe there was a mechanical damage of the windings. Too long mounting screws could cause this for example.
If the esc was burning out ur windings u would get a flux linkage issue, or something along those lines, ur mosfets if bad would also send out fault codes. Ur motors frying could be from lose mounts or from the orientation u have them mounted. And not necessarily the esc being the issue if u see 0 fault codes. The issues here could be bad enamel coated wiring, u could try flipsky motors or get another maytech. If u get a complete other motor brand and it happens again, look at the esc mosfets.
I was sure it wasn’t the mounting screws. But I checked this again for you all. There is more than 8mm between the bolts and the windings.
I then checked the cable connections and they are all OK.
So I decided to swap the stormcores from back to front. At the moment the weather is bad but a ride is planned this weekend. Then I can test the board.
@hummieee@Linesflag I’m going to loosen the winding of the motor one of these days to inspect it further
I really believe the current carrying capacity of the motor windings will almost always be less fragile than the mosfets which is why I advised Alex that this is likely a motor side issue. But it is definitely strange to see it happen twice in the same location. Will be interesting to see if we can pin down if/what the common mode failure is.
Today I wanted to use my board again. When I turn the board on, only the rear motors works. So checked the stormcores. Each one was on. Metr can is connected to the front. Metr is working perfect but only the stormcore on the back is detected. After rebooting etc nothing changed so I thought fk it lets go 2WD. After some driving the front motors kicked in for some seconds. Very scary and dangerous, almost fell.
So I decided to remove the can cable and only use the stormcore in the back. (The remote is connected on UART on the stormcore in the back).
Back at home I connected everything back. Only one motor in the front was giving a very high pitch sound when throttle. Motor felt hot immediately. So I turned the whole board off.
At this moment I have 0.00 trust in the stormcore in the front.
Can you rig it up independently on another board and run it in isolation? If you have problems with it like that, it’s more conclusive and might be easier to diagnose.
In the graph you can clearly see that side 4 has a negative duty cycle when turning in riding direction.
After doing again motor detection the graph is again how it need to be. And the motors are spinning normal how it need to be and the high pitch noise is gone.
I am looking for suggestions on how to solve this problem.
Both stormcores have already been slave and main. It’s always the same stormcore with these problems.
Firmware has been re-flashed several times.
