Overvoltage under braking!

Another day another issue!
This time its overvoltage under braking!
Cant find any fix myself,found a similar thread with the same issue but he ended up killing the vesc.
After using the st link to save my xenith its now running on FW 23.46 ive tried flashing it again with the same firmware via the unity app.
here are some screenshots of the bms settings…spot anything i haven’t?

I don’t understand what your asking?
You’ve provided photos of your smart bms settings page, what’s the relevance to an over voltage fault?

Is your bms not bypassed on discharge?
What exactly occurred, when did it occur, what charge level was your battery at prior to it occurring?

Yeah, on top of what Avi is asking I’d also be curious about your motor, battery, motor/battery amp settings, and regen settings

Im just guessing it maybe the bms from what I’ve been reading…bms is not bypassed for discharged,my xenith firmware was “bricked” i managed to recover it with my laptop and an st link but since then i have no brakes and an overvoltage reading in the hud of the unity app.

All my settings have been the same on this build 80 battery a…motor 60 a …regen -24 a… braking -60a

The bms was replaced and running fine the only thing that has changed since this issue was the firmware issue on the xenith,unsure if its related or my bms has just decided not to function as it should!

Ah, your settings are fucked. Your smart bms will not handle 80a.

If your bms is not bypassed then it will shut off charging on over voltage. That power has to go somewhere, so it may have bricked your esc.

If i recall there’s a fault counter in the android bms app that should say if it hit over voltage.


Why was your bms replaced?

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I can see how the thread may be confusing lol excuse my adhd! So i have full exceleration on a bench test just no brakes,ill try lower the battery amps to 60

Your bms is probably rated for 20-40a set your battery current with a margin below that number. You can find out bassed on the bms model number or in the app. This is why we bypass.

Did you replace the bms before or after the issue?

I need a full timeline to help.

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My bms is rated at 60a…i totally overlooked that when fitting the new one not sure what the old one was rated at! Its been running fine as well until this firmware issue,unsure if its related!
My xenith has now gone back in to this “read firmware issue” so ill have to sort that out with the st link! :crossed_fingers:

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So i found the old bms i replaced and it was also 60a! The previous battery owner thought it was 90a and had it set to 80a maybe thats what killed the previous bms!

I just replaced it for the newer version and kept the same settings “doh” well at least its not dead,think i will go the route of bypass soon anyway!
@Avi thanks for pointing out the obvious :rofl:
Ive been running this board on these settings for 2+ years now :man_shrugging:


So i couldn’t help but get moving again with this after work,was gonna leave it till the weekend but wanna get out carving by then!
Ive done the whole st link bootloader/firmware again and am happy it’s not the xenith causing the issue!
Im leaning more towards the bms causing this,i know there is a whole debate over bypass vs not bypassed but i have had no problems up until now and prefer to use a switch off the bms!
Ive configured all my settings and turned battery amp down to 60,on a bench test i can full throttle it for a while then get brakes but if i throttle it for a short time then try to brake it just hits the overvoltage issue…
Here’s a video,any suggestions or anyone that has dealt with the same overvoltage issue feel free to chime in…

I’d keep lowering braking and regen since it’s happening during braking. Otherwise I have no idea.

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What is the voltage of the battery during this test. Show us the home screen of the bms app, the one with the group voltages.


why is nobody asking for logs or xml

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The pack shows as fully charged to 18ah but the voltage on the 12s isn’t full,it looks like it is a problem on that,i plan to take the pack apart at the weekend check the welds and re-weld that whole group

Take a screenshot of the bms app home screen that shows where the individual pgroup voltages.

This is important!

All good brother,im pretty sure thats the issue now,i think the initial nickel i used to repar that group wasn’t of a decent grade! Once i pull it appart at the wknd I’ll see whats up! Appreciate your help :facepunch:

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