VESC acceleration boosts at high speeds

Hi. I always have a acceleration boost at high speeds when i go full throttle. And many people experience the same problem as i read in other threads. And i think that this is a software bug of the VESC.

My question is if people with other ECS’s experience the same issue or if it is only a known problem for the VESC.


I also experience this at around 25kmh. When the board reaches this speed it really wants to accelerate, even when I am very light on the throttle. Using VESC.

Does it also happen in FOC mode? Can’t use FOC at the moment so i can’t test.

It is not consider as a problem for some of us…


I made data loggings and i think the problem is that the duty cycle is not calculated correctly. Because it jumps from 0.86 to 0.95. Before that it climes linear.

could be your vesc settings and a long topic on it is here. when you’re going slowly the motor amp limit rules and when you get speed up the battery amp limit supersedes

I know all of that. Only the jump from 0,86 to 0.95 doesn’t make sence. Watch the video when it goes up to 0,86 duty cycle. The video is with constantly 50% throttle.

Data logging

It happens infrequently to me and I haven’t been able to log it via a logging app yet to see what happens. It would be cool to log also the throttle position (ppm value %), something that the current apps seem not to do, is that value something easily pullable from the vesc via uart or does it requires a vesc “custom app” setting + implementation (instead of uart+ppm control mode)?

From what I remember it happened to me around 30k erpm and only when pushing the throttle quite hard (80+% ppm), if I push it slowly (~60%) which is what I usually do at medium/high speeds, it never happens.

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its not a problem for me either. I’ve just come to expect it. It may be a bit of a curiosity though for someone who’s never ridden a VESC equipped board before.

If it is a software bug then it would be nice to fix it and get rid of the problem. I am also working on another control mode which gives you 100% throttle control even at high speeds. Because depending on your VESC settings you loose the control at higher speeds. That is the behavior when it doesn’t make a difference if you pull the trigger 50% or 100% at higher speeds. Power stays the same. But first i want to know if i can fix that issue with the acceleration boost.

@longhairedboy PS. I am a big fan of your builds

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i have found that making adjustments to the motor max actually extend the range of acceleration over full throttle so that its easier to maintain a articular level of speed, even lower speeds. The problem is that rider weight greatly affects this kind of thing so settings for a guy like me might be ideal for me but sluggish for a 200 pound guy. Vesc tuning is a very personal thing. I sort of wish i had an app that took rider weight and a selection of graphical acceleration curve depictions and just put the right settings in automatically.


Isnt @jacobbloy doing that app stuff?

got the exact same thing, it also feels as if i jerk the throttle. would be great if thats actually a bug with the duty cycle jump. clearly something for the vedder forums!

Yep, that happens. It’s like turbo boost lol. Scared me the first time it happened, but after that it’s kind of fun actually. My board that LHB built topped out around mid 30s, so I’d say somehwere in the 27-30 mph it hit like a sudden boost to get to that max speed.

Does this also happen with Duty Cycle instead of Current Control ?

I haven’t noticed this issue with dual Vescs, Motor max at 60a Batt max at 30a Maybe setting batt lower than motor prevents the turbo switch.?

Does it happen in FOC mode?

I don’t think so, not on my board. I’m running one board in FOC mode and acceleration is very smooth.

You mention a potential bug in bldc mode between 85 and 95%. Could be.
The acceleration boost on my bldc board is at around 20 to 25kmh, so closer to 50% of top speed.

@whitepony is using FOC for a few weeks now and has also experienced these bursts.

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Can somebody please verify if FOC mode also has that behavior? If that is the case, is it stronger, less strong or the same?

Chaka talked about this recently,

He thinks and I agree it is probably from Voltage Sag. When accelerating hard a Big Voltage Sag is created initially,… then when voltage comes back to normal Sag, this boost is felt!