VESC: How to get better brakes?

Hi all,

As most of you probably know by now I got a Lou board with a single hub motor that I upgraded with a Focbox. I thought that braking would be improved but I still struggle to stop when going downhill or at low speeds.

My initial idea was to increase motor min to -85A and battery min to -10A but it didn’t help and looking at the logs I don’t even come close to the set values. Interestingly the motor current even switches from negative to positive while braking as visible in the attached logs. Is that normal? What setting should I try next to get this thing to stop?

I am using sensored FOC and the battery is a 10S1P. Firmware is the current @Ackmaniac version 3.102 if I remember correctly.

hm interesting. tat has sensor correct?

Even 5A on a 1P battery would be pushing it. Really the only solution is to add more cells in parallel to increase the total charging current.

Have you tried learning to footbrake?

as you can see in the log my battery min setting is not the issue here. I am not even close to 5A

Just like how batteries can only deliver a certain amount of current before voltage drops, batteries can only accept a certain amount of current.

I know - please be constructive towards the actual issue. The voltage did not rise above 41V so there is still margin for the cells to take the current. It also does not explain why the current reverses and becomes positive while braking. The log shows the overall lowest battery min to be -2.59A and the lowest motor min to be -16.11A.

I don’t care about the health of the cells and whats good for them - I would have never decided for a 1P solution anyway. But this is a commercial board that I can only modify so much and a bigger battery is not possible.

Motor min becomes more dominant at slow speed, while the battery min value defines the brakes at speed. With -10A you don’t get a lot of braking. Best way to set up your board with linear braking behavior is to use the same value for both, motor and battery min. The generated energy needs to go somewhere and that is your battery. If you don’t allow the energy to shoot towards your battery, you have little to no brakes.

On top of that, your hubs have little (braking)torque.



So if I want to improve my braking on the Raptor 2 at speed; I would need to go from 10s4p to 10s4+p and flash other firmware on the focboxes to bypass the limit of -12A for battery min?

I basically want to be able to skid my wheels at full speed so I have all the control. At slow speeds, the wheels are actually able to skid already.

Can’t we bypass the battery for braking and send the energy to bitcoin mining or thin air?

Probably the motor is saturating, you can’t get the current higher than what you are getting no matter the limits

How small is the motor?

Don’t really know - it’s stock Lou. Smaller than my Jacob Hubs from the looks of it.

But why is the current polarity switching? And I can’t even reach -3A battery min - even though i set 10A. Why is that?

Are you using VESC-Tool, latest Version?


I am using @Ackmaniac’s current version (which is basically VESC-Tool)

There is a difference, and maybe now you get why Benjamin implemented the current settings as they are. If your Amp flow differs greatly from your settings, something is wrong in the code base. You would expect that the Amp flow matches your settings, so that you can actually adjust the system correctly, matching your motor and battery and desired brake strength - which is the case if you use Benjamin’s Software/FW. He knows exactly what he is doing! He coded the thing and has more knowledge about motor control than anyone else. There is a reason why things are the way they are… All you need to do is flash the original FW and use VESC-Tool, adjust the currents (e.g. -40A motor regen and -25A battery min.). You can adjust the positive and negative ramping (in PPM tab) to get the desired smoothness in the throttle stick/trigger. And if that is not enough, you can use the throttle curves to fine tune things even further. I can get every single board to run smooth like butter.


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Alright let’s see if this really is a firmware issue. I will flash the original version and try again.

A video with the app where you do your braking tests would be very helpful. Then you can do another video with the original firmware.

What i can see so far is that in the attached picture the speed was relatively low. Guess your motor isn’t a good generators. And volts are also not visible in the graph. So a video would really help.

@trampa you think it is wise to recommend -25A battery min for a 10S1P battery?

If you want to figure out the brake settings, you need to know the exact Amp flow at a desired brake strength. If the Battery can’t handle the Amp flow for a couple of seconds, but you need the brake strength for safety, you need to work on the battery (e.g. use stronger/better cells, higher P count), or accept that the brakes are not good enough for a safe ride. The braking energy needs to go somewhere and that is the battery. VESC-Tool will operate with the current you set. So it’s quite easy to adjust things to match your battery strength or desired brake strength. In the end it comes down to hardware limitations. Usually the battery is the weakest link in the chain when it comes to braking strength. This is why we all run high P counts on our boards. If a manufacturer sells boards with a 1P battery setups, he either accepts that the battery is operated outside it’s physical limits (creating a risk), or he accepts that the board doesn’t have good brakes (creating a risk). This is typical for designs aiming at a certain sales price point. Technically wrong solutions are accepted to meet the pre-set sales price point, no matter of the outcome. It’s all about bullshit marketing and fooling people around.

Advertised top speed for the dual drive: 35Km/h, Battery is 36V , 3000mAh (1P), Power output 3KW Obviously something is wrong with this product!

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My conclusion is that this is as much regen that this little motor can make. On my belted system if I downsize the motor pulley 2 teeth I get a noticeable increase in breaking power. So small motor with 1:1 ratio I don’t have much hope. Sorry.

Good luck with the software testing, I would be happy for you if I’m proven wrong.

Well I’d be glad if it is in fact “just” a motor issue. But the current polarity thing bothers me and seems counterintuitive for me regardless of motor size or gearing ratio. As long as I brake I expect to generate current and have negative battery current. It might be low but it shouldn’t become positive no?

I can send you the logs or a video. But the Lou is not that stable at high speeds and I did not feel comfortable holding my phone up while doing full-stop brake tests. I did not post the full log simply because of the enclosed GPS location data. It’s already illegal here so no need to push my luck :wink:

Voltage wise the log shows no increase above 41V.