VESC cutting out during acceleration

Hi Guys,

One of my VESCs (of two connected via can bus) is cutting out during acceleration. It was running fine before. All that has changed is that Im using new batteries (12s Nanotech A-spec). When i connect to BLDC tool and go to real time data there are no error codes on either VESC. Is there anywhere els to look for errors like a log or something? Has anyone else had this issue?


I also have the same issue but I figured it was related to the current limiting feature and learned to deal with it. Mine seams to only do it occasionally. Does it happen to you fairly often?

It dose it every time. when i first turn it on i can use quite a bit of throttle before it cuts out. it will cut out for about 3 seconds then kick back in but each time less throttle can be used before triggering the cutout. after a few times you can barely use any throttle. Seems to be acting like a thermal cut out. I might have to get the thermal camera onto it, see if anythings getting hot.


Just jumped off and flipped her over as soon as it happened to see the red light on the right (master) VESC flash a couple of times then a second later back to green / blue lights and it works again. Looks like its resetting its self upon acceleration.

Is there any way to log the VESC data without having to do all that git hub stuff? I looked at how Vedder did it and the process seemed rather overwhelming.

I looked into that recently and apparently the video-logger code is outdated and doesn’t work with new fw versions. There’s only one way: ride with a laptop.

Others may correct me here but I don’t think the current limiting feature will cause your VESC to cop out the way it did.

I had this issue once, it turned out my voltage cutoff limits were set too high and when accelerating the voltage sagged below the limit. I never was able to verify whether or not the VESC blinked red though.

I’ve been testing my dual motor setup with new VESCs from @chaka on the bench lately, and I’ve seen it happen a couple of times to one VESC. No clue what’s happening though.

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I just came across this post on the VESC forum, which might be a clue.

How long are your battery wires ? Mine are quite long, I might add a few capacitors and see if it changes anything.

Well i ordered another VESC and it arrived today. I switched them out and gave it a test ride. While the new board does not cut out, the other one (not the original problem one) now cuts out in the exact same way… :frowning: But it takes a bit more load before resetting. I’d say its tripping at around 40 amps, where as the one i removed was tripping at around 30 amps. So now i have two VESCs with the same problem. I should also mention that it takes around 1 second of 40 (ish) amp acceleration to trip. if you just flick it on and off quickly it will not trip. My battery wires are 8 AWG and fairly short, maybe 200mm so this is leading me to think that it may be a capacitor related issue? Maybe it only occurs at higher voltages? I am using 12S Lipo. In the thread that trbt555 shared, using larger capacitors fixed the (similar) issue.

Is any one else using 12S lipo and running VESC @ 50 amps max without issue?

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Thanks for the link! :slight_smile:

Did you ever get to the bottom of this ? If not, post screenshots of your BLDC settings. Even better, post a link to the XML

Did you see my reply a couple of comments up from todays testing? Will try to get screenshots, but the more i think about it the more i think it has something to do with the new slightly smaller batteries that i am using. Hoping a big capacitor bank will solve it! It was running fine on my original (slightly larger physically) batteries. Although the new ones did cost twice as much! The old batteries (2 x 6s turnigy 45C 4500 mah) had 8 AWG where as the new ones (4 x 3S Nanotech A-Spec 65 - 100 C 4500 mah) have only 10 AWG wires, but they are extremely short (15mm). But again the power cables running back to the controllers are 8 AWG. so i wouldn’t have thought that say 60mm of 10 AWG would make any difference.

Sorry, I missed that post. Just wondering, how are you reaching such high currents at 12S ? I’m 95kg and hardly reach 30A going uphill on my 12S setup.

You could connect the caps from another vesc in parallel to find out if that helps. Heck, you could even connect an unused vesc in parallel just for it’s caps.

Using the caps off the other board is a great idea! I hadn’t even thought of that, and yeah i can just strap the whole spare VESC to the bottom of the board. Thanks!

I have a 43" drop deck board and I’m basically trying to get as much acceleration as possible from two motors. Yes, even 40 amps is a great deal of acceleration! especially with 2 motors, it takes practice to be able to use. I could probably just (physically) use 50 amps with the test batteries, 60 was too much, but i think i can work up to it :wink: I like the sound of 6,000 watts haha

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Im having a similar problem, I can get both motors running on a bench test. As soon as I go for a ride 10 seconds in the master VESC drops out and I’ll get red flashing lights when I accelerate. I had this problem with the slave vesc, I re soldered the wires a bunch of times to rule out and bad wiring problems, ended up shorting it in the process, replaced it and now that motor runs fine. Now the master VESC wont run properly. If I do a motor detection the motor jolts very briefly twice and says “bad motor detection” i can get the motor running again if I reverse the phase of the motor wires and power cycle the vesc a bunch of times, then things will seem fine, I can detect the motor, then again, as soon as I ride it will drop out after a little acceleration and when I throttle it the master VESC flashes red lights (three flashes, break, three flashes).

The strange thing is its still talking to the other motor and will spin at the same RPM as the slave motor. It will only spin upto the RPM of the slave motor so power becomes very weak. If I spin the master VESC’s motor I can see the slave motor responding to the master motor’s RPM through CANBUS.

Any ideas?

I should add, Im using BLDC 2.8 with 4.10 VESC’s with 2.8 firmware. I’ve tried re installing the firmware a bunch of times, I’ve had the same problem with multiple firmware and BLDC versions.

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Do your motors get hotter than before? Sounds like a short

They seem fine, I can run the motors no problem when testing and I can get a few test rides in then the slave VESC will start cutting out and cutting back in seconds later.

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My motor seemed fine during pc testing as well but it’s shorted. Finding out if ur motor is shorted isn’t obvious. A multimeter won’t register the different phase resistance differences because they’re so small. I got an LC meter off eBay for 30$. It measures inductance and capacitance. The inductance reading is very accurate and I can see what the problem is. But it would run the test and ride with minimal throttle but more than a bit of throttle and it would coast. With forced repeated hard acceleration, going not far up a hill, it got very hot

I can run the motor fine with my other VESC so I don’t think there are any shorts. I assume the VESC is faulty. Pretty sick of screwing around with VESC’s.

I’m having these power cutting issues also. When going at slow speeds at flat area there is no cutouts but when accelerating or going uphill these cutoffs are really bad. My battery wire is pretty long (40cm).

No faultcodes on vesc FW 1.14 Motor max is 60A Battery max is 40A I’m running 10s

Does anyone made any solution to this problem? @Ross @Moja
Sounds like capacitors should help. What kind of capacitors works best?