VESC - is pushing the board good or bad?

It’s been said specifically that the energy produced when just pushing and not having batteries attached will ruin ur stuff quickly. Check vedders site

You said many times “check vedder’s site” - post the link, please. I can’t find it. I’m really interested to see what’s the problem that causes that.

My theory ( again, THEORY, I don’t know how it works, that’s why am I asking you for the link ): Motor is spinning => You get voltage on it’s terminals => there is no ( or very small ) current => Voltage can rise easily => Voltage reaches cricital level ( at certain speed ) => something on the board can’t stand ( no longer works as an insulator, voltage barrier is broken ) => high current flows ( short circuit ? ) => component(s) get damaged

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Thank you!

So the general advice then sounds: unless you break or go crazy fast, you should be fine.

no. if you push the board without a battery attached you will blow it up!

braking without the battery should set off the high voltage limit and nothing will happen, hopefully. no brakes will happen for sure. but pushing without brakes is still enough to ruin the vesc. In my experience it slams on the brakes.

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With no battery is bad: if you brake, the voltage on the bus-line will rise very quickly, possibly causing over-voltage-damage before the VESC notices that something is wrong.

So without a battery, the accidental brake command will quickly fry the VESC (as long as you’re moving). When going down a hill faster than the unloaded speed, the NO brake commanded situation is the worst…

Turning the VESC off isn’t going to last long: The motor will power up the VESC. Then if you somehow activate the brake… you’re toast.

There is no reason why it should get blown up when breaking is not applied. There is just no current that coud damage something unless you allow it to flow ( using breaks ).

If the VESC starts to break itself without a battery, then you have a big problem.

read the link i linked. o wait it’s not there. let me find it

I read it and pasted few quotes there already. Basically what they said is that if you break or go crazy fast, you can damage it.


So, with a bad reciever connection to the vesc I have gotten extreme unwanted brakes with no battery connected

So if your receiver tells the VESC to break ( by a mistake ), it will break and you know what happens.

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maybe you’re right. i thought i’d read somewhere on there otherwise. how much current does flow with coasting and no batteries? is it limited? there’s some current flowing to get it to light up…but too much would be too much no? the quote you put in is me. maybe thats why I assume it’s bad because it’s thrown me a couple times with the bad receiver

I = U/R. If battery is disconnected, there is infinite R. But there is a microcontroller and other things that require some small amount of power ( a lot of R ). Remember, the higher the R, the lower the current. So if no breaking is applied, you got maybe 30mA ( I don’t know, I’m guessing! ) of current that is used by the board itself.

Once you break, you probably get short circuit somewhere due to too high voltage and that means a lot of current is transfered directly to the heat = bye bye your VESC.

I can’t really tell you anything more, I don’t know how the VESC works.

i understand you with the ohms law but with the motor increasing in speed and building a greater voltage…at some point the resistance of the esc maybe isn’t enough and too much current will run though? you say you don’t know the vesc in particular but i imagine at some point this will happen. but the more I read the more I’m not finding what I said before and the vesc will not die being pushed without a battery. just braking

Well, if you go crazy fast ( like really crazy ), the motor can generate higher voltage than the semiconductors on VESC can handle and they will became conductors. In that moment, your VESC is dead. But the same can happen even if the battery is connected ( just smaller chance as the voltage will be smaller thanks to the load - the battery ). So this is a different story.

Its almost midnight where I live, better gonna sleep. Take care.

Thanks for breaking it down.

With the fets, the transistors, they open or close the current, …when the board is coasting it lights up, so there is a current coming through and u say it’s very small, is it through programming that the current will be limited to maybe 30 mah and it will stay at that current until the fets voltage limit is broken, or does ohms law dictate the current increases with the voltage? A fixed resistance.

Which brings me back a step, what decides how much current is let through?

Hummie is correct! i used to push with the esc off and it would pop on and throw me off. when magnets pass over windings like in a motor it creates electricity. that can power on the esc. you can test this by taking the 3 phase wites from your motor and grounding them all together. than spin the wheel by hand and you can feel the power stall the motor. make sure you have the motor disconnected from the esc and any other electronics.


There is only as much current as is needed, unless there is a short circuit. When you break, the current goes thourgh the battery and it charges it. When there is no battery, VESC somehow redirects the current through itself ( I dont know, just guessing ) which probably ends up in a short circuit ( very small resistance, high current flows ) which destroys your VESC.

Hi. I am pushing with connected batterys, but when my battery was near to empty - only 4% left, on pushing my motor blocking and I almost crash. I was repeated 2-3 times to test… Is that means that 4% left of baterry means that battery are empty (in that moment) and lose contact?

xxxxxxxx. No idea

I have now dual FS vescs and FS motors with 6S batterys. But similar thing was happened before with my single chinesse motor and chiping vesc…

I am running a Raptor 1 DIY build since many years and I regular push with the battery switched off (longest was 3 miles). Never had any problem and I am running Enertion Vescs (not the focbox).

as long as you have a battery connected youre supposed to be fine.