Popping Caps on ESCs - Faulty ESCs? Or Something in my setup?

Hardware Other Hardware
1

I purchased 8 of these ESCs for my build: https://www.amazon.com/gp/product/B07K76TGTR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I have smoked 2 different motor’s ESCs now. A pop, fizzle and puff of smoke each time. This last time I was trying to do the Compass Mot calibration. Both times it was 15-30 second after dropping the throttle to 0.

They are setup for Dshot1200 using Aux 1-6. powering SunnySky X2212 980kV (hover @ ~5A each) motors and 10x4.7 props

Power Setup:

First ESC:


Second ESC:


These were both on different arms - so it would seem like power distribution is not an issue. The frist was also on a different Cube & carrier board pre-replacement for IMU service bulletin. I think that can rule out power distribution and FC.

Is this simply a case of faulty ESCs with poor quality caps? ESCs overrated at 35A? Or should I be looking into the rest of my copter closer? Anything in my power setup I should look for?

Can anyone recommend a reliable ~30-35A Dshot1200 ESC?

2

How long are your battery wires from the ESC back to the PDB?

3

~3“. a little over-gaged @16ga

4

General tip: Use short wires and add big electrolytic capacitorss of at least 470uF. The ESCs may come with long arrays of SMD ceramic caps, but they won’t save your ESC from voltage spikes.

Here is a very insightful read on how stray inductance, i.e. long battery wires can destroy ESCs: https://www.rcgroups.com/forums/showthread.php?952523-too-long-battery-wires-will-kill-ESC-over-time-precautions-solutions-workarounds

EDIT: Also, assuming the Sunnysky 2212 980kV is analog to the T-Motor MT2212 980kV, I think 10" props aren’t meant to be used with 4S.

5

Are you implying that 3" leads between the esc and pdb is considered long?

These motors are rated for 4s and 1047 props are recommended according to sunnysky:

I know I’m pushing these motors when at full throttle, but they’re only drawing 4a at hover. At hover with full battery voltage, each motor is only making ~70w. Max is 300w.

I have never been to full throttle or anywhere close. Am I underestimating my power draw? Overestimating the capability of these motors?

6

For now pls disregard what I said about your motor-prop setup. On the other hand I am quite sure voltage spikes destroyed your 2nd ESC judging from the burnt SMD capacitors.

On Copters running 4S LiPos voltage transients can reach 25-30V — enough to destroy an ESC rated for 6S (25.2V). The reason MAY be wire inductance OR regenerative braking, but adding capacitors always help.

1 Like
7

Would I see voltage spikes in the log? Or are we talking faster spikes than that?

8

I’d say the correct question would be “What is the total length of the wire from the battery to an ESC, including the battery and the ESC leads.”

If it’s more than 20-30cm, then you should definitely consider adding large-ish capacitors at the input terminals of each ESC.

If it’s less, then maybe the ESCs are badly engineered or have less capacitance at their input out of the factory. But again, the solution is the same.