30 mph cutout to superman

I just had my first fast fall…

My board lost power going up a hill… dual FSesc 6.6, kugliss antispark, bypassed bms 12s4p 30q.

Any ideas how I’m going to trust it again?! Crash at 14:16:02


Are you sure you did not voltage sag it to 0%?

More vendors for ESC need to do what boosted and Enertion does, it gradually slows down as the voltage approces 0% instead of a hard cut off.


The voltage dropped to 26.7 then briefly recovered then the escs shut off. I had to power them on again post dive… doesn’t seem like sag?

Your voltage dropped to 14.6 V right around then. Any idea what that was about? Maybe a wonky battery cable connection and you hit under voltage?

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Check your battery pack it looked like it went down to 26v and then down to 14v looks like broken nickel strip or etc. Also sagging is pretty big from 45V down to 40V



The drop to 14 was the total shutdown so the voltage only recovers after I push the on switch a few seconds later…

Ahh right, wait so whole board shutdown? The definitely check connections


It is not sag.
The vesc (if properly setup) gradually reduces power when it reaches battery voltage cutoff start.
As @Kug3lis said, check your battery.
You may have a bad connection somewhere.


@Amazingdave Are you OK? Do you remember the whole thing?

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I am afraid it will hurt at night on the bed :grimacing: but if the worst is on the picture, that is a pretty lucky outcome after crashing at 48 kph

Interesting observation, even though it looks like the battery was cut out, VESC was still getting the power from the motors! (regen), the voltage did not drop instantly


The drop in the voltage to 26 and 14, is just the decaying sequence once the battery has shut down. A bit of effect from condensators and motor inertia giving a bit of regen. It’s likely to be the consequence, and not the cause.
It started to shit itself just after the peak where you drew over 60A out of your battery. And over 80A on the motor. Isn’t there anything spec’ed to those limits somewhere in your chain?

These cutouts are really problematic…

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Ouch but still good considering, no errors reported?

I would pull it apart and check all connections very carefully

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The pain is developing nicely… my knee is badly bruised and my pelvis is seriously painful around that road rash… my motor cross jacket saved me from worse. oh and my helmet is cracked so that’s both a positive that I’m alive and a financial pain to bear!

I’ll strip the battery tomorrow and get to the bottom of it all.

I am feeling like a rather sore but extremely lucky mother f***er.


No errors… I cruised gently downhill to my van with the board braking normally. as you might imagine, I took it really easy! I won’t be riding till it’s had a full strip down.

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I was going full beans up a long hill but It should all be good at those draws… 12s4p 30q, dual fs 6.6, 150A fatboy AS switch, bypassed bms. My temperature was good…
Something didn’t like it though!

Yep it’s all crystal clear! Board slowed a bit for a heartbeat then it threw me… I’m layed out with a bit of a whip to the head and a good long slide… I look back and my board is just sat there looking perfectly happy with attempted murder.


Glad to hear it. If you had lost consciousness at all that’s definitely something you’d want to get checked out. I fell on my analog longboard a while back and got a concussion out of the deal. Took me a few weeks before I felt like myself again. It was really strange.

At any rate, I’m glad you had the right gear on and it wasn’t any worse. Wishing you a speedy recovery and luck with debugging.


Hey man sorry to hear about your accident, do you have a charge/discharge BMS? What brand and what model?

So when you say it cutout, did it brake? Or did your acceleration just suddenly die?

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