Gremlins! Rover ESC chirping and wires to battery heating up and "jumping" when armed

ArduRover Rover 4.2
1

Hello! Total newbie to the Ardupilot space here.

I have built a rover using a Traxxas slash 4x4 and a Pixhawk 2.4.8 kit that I bought off aliexpress. my goal was to convert my existing remote control car into a rover for a school project. I have got it working and completing waypoint missions, but I am having some very strange hardware issues when I arm the vehicle.

My Traxxas slash is using the VXL-3S ESC that came with it. I have a 6ch FLYSKY receiver connected to a PPM encoder, which is then connected to the Pixhawk. When I arm the motor via Ardupilot and use the safety switch, my ESC goes haywire. The wires connecting the ESC to the battery get very hot (which is concerning, they are 12G wires) and they jump up and down like they are trying to pull themselves out of the ESC. When they “jump” the ESC makes a chirping noise. I have tested the ESC without the Pixhawk and PPM encoder, and everything works fine. The issue seems to be intermittent, the first time it happened it melted away what I believe to be a fuse on my power delivery cable (see pic)

PXL_20230522_125111440(1)
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I then ran the rover without this cable, supplying the Pixhawk with power only via the ESC’s PWM connection, which is not advised, but worked until the other day when I started noticing the gremlins. I re soldered the broken part of my power supply and tried again, but the chirping/jumping/hot wires continued, however, the chirping was much quieter.

My current plan for troubleshooting is to try a different ESC and see what happens, maybe traxxas “intelligence” is causing issues?

Any help diagnosing this would be appreciated, Thank you in advance

Feel free to ask for any other info, I have not checked logs yet…

2

The “fuse” that you burned out was the shunt resistor which is how it normally measures current. It would only burn out if you had a short on the esc wiring or even the wires on the power module if you soldered any of the wiring there.

3

Your cabling is confusing; see this. I think that universally the 50 mohm shunt (x20 constant to measure current) is on the PCB component side and on the positive supply (red wires). If you change that convention things get very difficult, even to check. So may be that you have a polarity inversion somewhere and the heat comes from a protection diode in parallel on some ESC.

Are you using a multimeter (with beeps) to measure voltages and check connections?

4

The shunt resistor is on the positive side, the negative side was just a circuit trace…unless that circuit trace is meant to have a set resistance?

I did not consider polarity inversion, and I will have a poke around with a multi meter tomorrow.

I would be skeptical of the power delivery cable being the problem because I still get the same issues without it installed…

to clarify though, I have not done any hardware modification apart from repinning my GPS, and “repairing” that power cable.

5

Update, Just in case someone else runs into this issue.
I had a spare ESC lying around, amazon special, and tried it with no issues! I am not sure yet if this is the gremlins being intermittent, or if the problem is genuinely solved… Time will tell