Poor standstill start

Hi, I recently finished a MTB build with two unsensored motors (2 x 2000W) and VESC 6.6.

I’ve been running until now an AWD hub motor setup and I got very disappointed with the difficulty that the MTB has to start from standstill. If I’m on a flat way it manages to accelerate but if it’s more steep it just cannot start with me on top of it, which is very annoying and almost embarrassing.

Is this possible to improve by tweaking with VESC configuration or do I just need sensored motors?

The reason you have a bad standstill start is that you have unsensored motors. Your Motors don’t know which direction to turn until you give them a small push. (On a flat they are able to do it with some cogging because it takes the values from your Motor detection, but thats not ideal.

Benjamin Vedder coded a new feature that could help you called HFI.

Go over to the new forum (make a new account and leave this place behind) and read through the post, you can find a tutorial in the comments on how to set it up. https://forum./t/vesc-tool-2-0-and-firmware-4-0-the-beginning-of-a-new-era-serious/18881

and here is he video :


I did see Benjamin’s video on YT about HFI but to be honest I didn’t understand how to enable it…

Will look at the tutorial, thanks!

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I could follow the tutorial but regardless of the parameters, my plot looks always a mess like this:

The end result is that I cannot even start when using HFI.

I would say starting uphill is hard without sensors, unless gear ratio is big in first place

Though this hasnt been a problem for me since i dont have many hills around, though i do have sensored motors now and starting from stops is no problem no, before I always needed a push to start…

Whats your max power output (amps)? It might be because you are actually laking power. I use a sensorless setup using the good old BLDC mode, and that thing wants to fly under my feet :grin:

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That’s really weird, which motors do you have?

I have 100A available, should be enough I guess :slight_smile:

Dual 1500W, 5055. Bottle neck can happen in two places mainly, BMS and Vesc. Make sure your BMS can actually deliver that power if you are not bypassing it.

Wait, I just saw you are using hub motors, those things don’t have enough torque unless they have an internal planetary reduction gear or something, belt drive is going to give you the punch you are looking for.

I’m bypassing BMS and using a VESC 6.6 from flipsky. Well, the AWD hub motors were from a previous setup and they worked much better on standstill startup…

Do u have pictures? I also missed the point they are hub motors…

Sorry for the confusion, they are not hub motors! I just mentioned these from another build that I have for comparison purposes.

I’m using this kit here: image

with dual Belt-Drive 4000W(2000W*2) N6354 Out-runner Motors.

if @rich / @Andy87 is still on this forum, maybe they can give insight.

I didnt have vesc back when I tried to do uphills with unsensored motors, so there might be a way to make them work uphill too.

Though, there are some methods to make sensored motors on your own. some ppl just 3d print outer ring to be attached to the motor outside and this seems to be working also to get the hall sensors working.

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if HFI doesn´t work out (didn´t try it by my own yet) than AS5047 encoder would be an option, or external hall sensors like you mentioned.

I think his problem is more about power shortage, sensored vs unsensored only contributes to how smooth you take off. Unsosored would hesitate during take off but will definitely give you the torque you need once motors starts spinning. I suggest you take a look at your vesc settings, and better monitor your power usage during takeoff to see how it is actually used.

Yes, but my problem is only on the take off, when I feel some cogging. Afterwards I have plenty of power.

I feel you, I can’t stand unsensored motors, it’s so embarrassing. If HFI really doesn’t work (try it again) then maybe get sensored motors or add sensors. 6355 motors are not the best hill climber I would go with at least 6374. From which cells is your 10s3p pack made or is it a chinese one?

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I’m afraid already ordered a pair of sensored 6374… :relaxed:
In any case I think the VESC is not working optimally, I’m trying to figure out what’s going on. I guess it will suck less, let’s see.

Regarding the battery pack, I did it myself with 21700 Molicel 4000mAh 45A cells. Quite powerful ones.

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P42A is very popular right now. BTW, even though you have some very experienced dudes helping here, try forum. esk8. news for even more assistance.

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Nice to know I’m not missing something by choosing these cells, the specs are amazing and my experience with them so far confirms it.


Keep in mind they’re more of a 30A cell not 45A, they reach near thermal limits running at a constant 40A and cycle life degrades significantly.

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