I‘m really interested in this. I hit that overvoltage so often… almost dislocated my shoulder the first time it happened, and 5 times in 2 yrs was really enough…
I found this simple circuit:
source I think i can build one, but i can‘t program digital outputs on my vesc. Could someone teach me that or head me to a guide, or simply do it 4 me?
I still need one too, overvoltage and battery cut off in general is scary. I’d rather not experiment that at all, you getting thrown by it 5x times is too much already.
Please report how it goes if you build it, on my side I’ll ask an engineer what he’d do/advise/correct based on both this circuitry and the ones shown previously.
Was thrown off once, jumped off and run it out the other times. The 5 shoulder dislocations were from snowboarding:/
The circuit seems dead simple to me, but i‘m a software noob and would need to change vesc settings, so it would give me 5V somewhere instead of going overvoltage cutoff.
Damn, didn’t know snowboarding could hurt this much (actually I may have been very lucky till now with snow sports : never broke / hurt anything despite many falls) !
I checked the full page you linked, yea it does sound pretty simple and hopefully reliable. Which resistor and which MOSFET would you use for this method ? Can it trigger upon overvoltage detection before the VESC issues a cut-off, it it relies on the digital output ?
Didn‘t plan anything so far. But any mosfet (as long as it can handle the loads) should do the trick. For the resistor, one of the big ones linked previously. Or maybe can find something gimmicky like the heater wire but with some arcs like in star wars pot racers maybe… probably not:D
I don‘t get the last part, but this would instead of going overvoltage cutoff rise a voltage on any chosen pin wich would then open the mosfet. That puts the resistor in parallel with the battery and the Voltage in the bus wire that would normally exceed battery voltage is droped by the resistor. There is no overvoltage cutoff anymore, the digital output and this circuit instead.
Sadly i can‘t program:(
Tried to make one a bit more simple: edit: look below for new schematic
Basically you only need a programmer to be able to test it ?
No this one does not require a signal fom esc.
You set a voltage with the potentiometer and it should work. i got help here recently, will make one soon i think
If you can lay it on a PCB under 50x50, I’m up to participate as test guinea pig haha! I might as well keep it in the fam’ instead of going freelance route. I’ll try it up to 13S voltage. I can relocate the resistor if it is big, “a la Mellow” with an aluminum cylinder.
I’ll need many brake choppers units in the long run, and push it to the DIY scene along the way if it works as a good standard !
How big should the difference between trip voltages be? lets assume a 10S 42V battery: trip on voltage is set to 42V, now we break but battery is already full and we would exceed 42V. instead of getting an overvoltage cutoff the break chopper turns on. Voltage suddenly drops (how much is dependent by the size of the dump load and battery capacity), and the chopper would instantly turn off again and may beginn to oscilate. Against this we create a second trip point. How much lower should that trip off voltage be?
i doubt 1V lower should be fine?
Depends in the load itself IMHO but looking at the unicycle project shown in video, a 0.5v max trip might be way enough.
Supposed behavior I see is : when he brakes is : it does actually exceeds the first trip voltage shortly and comes back under the value. But it still is fed with a lot of power from the regen braking, so voltage kinda “fights” to rise back to a higher level.
Edit : OK reading again what I wrote, had to correct it.
Given how the Zener opens gradually till full open (and vice versa) can’t you use 41.5v to 42v? I was guessing 41.7v trigger earlier cause it brings a safe margin too.
this should be the final circuit
the zener D1 just creates a 7V reference voltage, D2 is 12V supply for the op amp.
the first (high) trip point is set by adjusting the pot R4 the second (lower) trip point is created by adding a hysteresis resistor (R8)
if i set 41.5v as first point and use 2MOhm for R8 the second trip point becomes 40.9v. (1MOhm resistor and the second trip point becomes 40.4v)
Hey, how is the circuit going? Did you get your testing units done? I wanna try this too!
This is fairly common in high inertia industrial drives. I’ve installed a few of these to shed dc buss voltage.
Dude we absolutely need this into our DIY. What are you waiting for? 
Edit : On my side, I’m taking some time for myself, will press the throttle again in September. And I got a shlongboard FWD to figure out for August !
Take a look here: http://vedder.se/forums/viewtopic.php?f=15&t=586#p3515 http://vedder.se/forums/viewtopic.php?f=15&t=1723&p=9047#p9047 i also opened a topic on this forum, but the only response was that i rather just shouldn’t charge my battery full and that guy claimed to be an electrical engineer-.-
Lol that sounds like somebody I’ve met here too. Still we got good tracks with your topics and what has been posted here 
