Flipsky FSESC troubleshooting

Howdy, I’m in the process of building an electric mountainboard I seem to have possibly killed one of my vescs I’m looking for help at best or to warn others against being stupid like me at least. I’m using 2 flipsky FSESC 6.6s with heat sinks and built in anti spark switches. I finally got the board working a few nights ago and left it to sit so that I could fully test it the next day, the next morning 1 vesc wouldn’t turn on, still getting power to the switch(the light on the switch comes on) but I’m getting no response from the vesc I’ve tried swapping switches to see if the issue was just a bad switch but it seems to be a problem with the vesc itself. My running theory is that in placing the (conductive metal) switches under the phase wires, I may have shorted out something in my vesc, my only other theory is that somehow the internal circuitry for the switch has been compromised. Any troubleshooting tips would be greatly appreciated. I have a multimeter but have no clue what I would be checking.

The FESCs are notorious for being easily shorted out if you touch or even think about touching the PCB while it has power. Do yours still have the clear plastic wrap on them? without it there is no protection from shorts from what I’ve seen on here.

I had to remove the plastic from mine to remove the heat sink so I coated it in conformal coating so that I wouldn’t accidentally short it. I still haven’t finished the enclosure for mine so if that isn’t the issue I can’t help much

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I had a MOSFET fail for the onboard anti spark switch on mine, the power button lit up but did nothing. I removed the switch and made a loop key that seemed to work and turn the ESC on.

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I do still have the plastic wrap on the vesc, I had to cut it open to free the power switch but this was only after the vesc had failed and it’s still wrapped around the majority of the esc

Do you by chance have any documentation on the process? Or a way to check if that’s the same problem I’m having?

I followed the loop key tutorial on the forum, sorry I can’t be sure if that’s the issue you are having you would have to test it

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How would I go about testing?

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No Idea, Id make the loop key as they seem a pretty good idea anyway. Im very new to this so definitely worth seeing if someone with more experience can offer further advice.

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I’m just not entirely sure how I would replace the built in antispark with a loopkey, is the ESC supposed to automatically turn on when power is applied and no switch is connected? How exactly did you bypass the built in switch?

I think so. When I unplugged the switch and put the loop key in it powered the ESC up. Seemed to bypass the anti spark switch.

Hmm, I think I might have a separate issue, plugging in the battery with an XT90S doesn’t seem to turn it on when the switch is removed, thank you very much for your help though.

maybe your mosfet failed off and mine failed on? hopefully not.

Something to look into, thank you very much

I’m going to hail @aletheuo and @Gamer43 it seems you both have documentation on bypassing the mosfets on an fsesc, would bypassing the mosfets be a possible solution for this issue?

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Hard to tell without knowing exactly what failed.

No blue light on the ESC?

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No lights on the ESC, that’s correct.

On the vesc 6.6 dual at least it automatically turns on when no switch is connected, my button switch is dead and it still turns on via the loopkey

A few things you can check with it unplugged

  • Resistance between phases. Should be 80kohms or so
  • Continuity on a 3.3v to gnd pin. Should not be short.
  • Continuity on a 5v to gnd pin. Should not be short.

And with it powered up

  • Voltage at the anti-spark mosfets. Does the battery voltage make it to the drain? (other side)?
    ** if no, you can try manually shorting the two switch pins to see if it does something different
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That I have indeed tried, I unplugged the switch and plugged it in using an antispark XT90S instead of the switch but no luck.