I have suddenly NO MORE BRAKES

Afraid AF to ride now. Thi morning i changed the BMS of my last board. I haven’t touched anything FOCBOX / TX side yet now i can only accelerate with the throttle and I have absolutely NO BRAKES anymore. I haven’t touched anything on the BLDC sofware i ve checked again and I don’t see the problem.

I would point to the BMS being the logical culprit. Care to share some info on what BMS you have and how it’s hooked up and what the overall change was?

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Also… your BLDC tool is upside down…

Just kidding. Hate when that happens to my uploads too


Is the battery charged to full? The BMS might cut off in this case.

No the battery is charged to 80 %

It’s exactly the same BMS i had before it’s a Bestech 100A 12S

If you can, just remove the BMS and try to connect battery directly if that helps, if not it might be easiest to redo the settings (unless you have a spare remote laying around) and if still no change try a different remote.

I don’t wan’t to remove the BMS since i used my last shee of heatshink. I m pretty sure i did everything right for the BMS ( it’s just 2 negative wires not rocket science ) I tired to apply default configuration in the app config menu and not any changes… when i hit the throttle i works flawlessly but there’s absolutely no brakes and sometimes the throttle don’t work it’s such a weird behavior. Why would a bms would make my vesc act like that ?

I have typed faults and this resulted : i dunno what i means

yup. ‘‘‘tis the bms. don’t fully charge your battery and you’ll be fine.

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Either that or a cold joint on the new BMS from his wires…if nothing else changed(cold joint, high resistance low current capability either direction) could cause your faults or broken series connections


I think he said he is only charging the battery up to 80%. Full battery shouldn’t be the issue then. But I agree it looks like your bms is not allowing your vesc to dump power to the batteries thus not allowing it to do regen braking


oh yea didn’t see that. i think @Deckoz is right

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Measure each cell voltage. Maybe the bms is not balancing well and you have one cell near 4.2v while the rest are at 80%. This could trigger an over voltage protection on the bms also cutting regen braking

Also, check the style of BMS you have doesn’t require you to use the C- for discharge as well as charge or the other way round P- for charge aswell as discharge…?

That’s what i tought but i ve been very carefull with soldering sinc i already had issues with cold joints in the past. I what you say is right i shouldn’t have any power to accelerate either ? I can accelerate as much as before can even reach 65 kph i just can’t break, so it’s returning the energy the problem i think I have to admit i m clearly lost on this one spent almost the day on this one and no results so far

Can you clarify this as the two conflict.

-your throttle works normal and the brakes don’t work -your throttle is janky and your brakes don’t work

Clarify this too -your BMS is used for discharging -your BMS is bypassed for discharging

Your bestech BMS -has an eswitch -does not have an eswitch

Fyi that’s backwards

BMS Labels(not all are on every BMS but they all are the same meaning) -P is discharge negative (on every BMS) +P is discharge postive (rare) -B is battery negative (always on every BMS) +B battery postitive (rare) -C or -Ch is charger negative (on most BMS, if not available use -p)

There is no +C as the postitive side of the charger either connects to directly to the battery positive, or the B+ on the BMS. On BMS with no C ports. Negative charger goes to -P, postitive still goes on battery positive or b+ BMS terminal

Sorry i m not clear enough.

The throtle is normal but janky 1 time out of 3 and no brakes

I’m afraid i can’t answer this question.

I don’t use the integrated e switch because the last one failed so i use an antispark. With 80A fuse

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The soldering on BMS

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