Enabling regen on China KU63 BLDC motor controller 36V 250W

I'm looking to enable regenerative braking on my e-bike but i'm kinda a rookie on this subject.
after some research I was thinking about connecting the X with the DS to activate regen but then I would also like to add a button so i can choose between regular braking or regen braking but i don't know where I have to connect the cables of this button.
I have the schematic of the controller and a picture of the controller.
do you guys have some other options maybe ?

raedet said:

after some research I was thinking about connecting the X with the DS to activate regen but then I would also like to add a button so i can choose between regular braking or regen braking but i don't know where I have to connect the cables of this button.

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If connecting X to DS enables regen, then that is what you must switch to enable or disable it. Otherwise, it is whatever connection you must make to enable or disable regen.

Keep in mind you may have to power cycle the controller to change modes (some do, some don't), so it might not be something you can switch while braking.

I can't tell anything about wiring from your schematic, as it is too low-resolution to read any markings; they are all blurred out. If you have a high enough resolution version to read all the markings, you can attach it to your post and we can see if it has useful information.

Thank you for the reply I don't have a higher resolution but i do have a Url to the website where I found the schematic https://www.avdweb.nl/solar-bike/electronics/ku63-motor-controller

Ah. He has a link for the full resolution readable version right above the "thumbnail" image, as a PDF file. I've attached it to this post for future reference in case that site ever goes down. Note that this schematic is specifically for the version that the person running that site re-engineered from a 5-year-old (at least!) design of the KU63, so it is not the same as the versions you can buy anywhere.
View attachment China-BLDC-motor-controller-36V-250W.pdf


That site itself doesn't reference regen braking, only motor-shutoff-braking, so it's possible (even likely) that the version documented there doesn't support regen braking at all. (this is not uncommon). Nothing in the schematic helps indicate what you might be able to do to enable or disable or affect regen braking.


So your best bet at this point is to try adding wires from a switch to the pads you think might work, and see what happens when you have the switch on, vs off. If it doesn't affect anything, try shutting off all power first, then changing switch states, then turning power back on. If it still doesnt' affect anything, you could try other pads with the switch, or add switches for *all* unused pads.

Note that it is common for functions to be enabled or disabled by connecting the labelled pads associated with them to a ground. Someetimes they are changed by connected to a 5v source instead, or to another labelled pad--but usually you ground them.

Without knowing what your specific version of the controller, including it's specific firmware version, was designed and setup at the factory to do, experimentation is the only "sure" way to find out, but it does risk making the controller nonfunctional.


Another option is to checkout Casainho / Stancecoke /etc's Open Source Firmware OSFW thread(s), and see if yours is one of the compatible models, then try using the OSFW instead, which usually does allow quite a lot of customization of controller operation, as long as the hardware you have supports the function you want.

Thanks again for the help, it's a school project for my last year in high school. I chose to mod a (older) e-bike so it can brake with regen im not the best with this electronic stuff, i wish i was , but i hope this projects helps me more with understanding the subject.
I have read several post on here but every controller is different the best thing now is to test and observe, as you said.
i also thought about programming the controller so that all mosfets stay open when braking but this would be too complicated i think
and something else the e-bike that i have has a geared hub motor ( DC 24V 250W) so now the motor won't generate electricity but if i solder the freewheel it would (by my guess) but then is the question will it get too hot ?
Im trying to do as much as i can with the parts that i have and not buy something from eBay or amazon because then i wouldn't learn as much.

raedet said:

Thanks again for the help, it's a school project for my last year in high school. I chose to mod a (older) e-bike so it can brake with regen im not the best with this electronic stuff, i wish i was , but i hope this projects helps me more with understanding the subject.

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Keep in mind that stuff that came on a premade (OEM) bike that doesn't do regen probably is not capable of it at all, especially if it came with a geared hub that has an internal freewheeling clutch. There would be no reason for them to include the option since the motor can't use it without modification, so you may need a differnet controller to do it (possibly a different motor).

i also thought about programming the controller so that all mosfets stay open when braking but this would be too complicated i think

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If it is compatible with the OSFW then you dont' need to rewrite the software, just change the settings appropriately, if the ahrdware supports it.

If you start from scratch to make your own control software (because youc an't read out what's already in there), you'll probably be at this for a few years to get it to operate the motor normally first, and then potentially more to get acceptable braking. You'll also blow up a lot of hardware in the process. (there are a lot of threads about such things, including hte OSFW threads, if you do decide to follow that path)

and something else the e-bike that i have has a geared hub motor ( DC 24V 250W) so now the motor won't generate electricity but if i solder the freewheel it would (by my guess) but then is the question will it get too hot ?

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You can look up "lock clutch" and similar terms here on ES for geared hubs to see how others have done it, but normal electronics soldering probably wont' work, as they are usually steel.

How well it works depends on the motor and the controller and the battery and the wheelsize, etc. You can get some idea of this by going to https://ebikes.ca/tools/simulator.html , reading the entire page so you know what everything is and how it works, and then setting up some different systems similar to what you've got, to compare operation under the different circumstances you want ot use it under.

Keep in mind that stuff that came on a premade (OEM) bike that doesn't do regen probably is not capable of it at all, especially if it came with a geared hub that has an internal freewheeling clutch. There would be no reason for them to include the option since the motor can't use it without modification, so you may need a differnet controller to do it (possibly a different motor).

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Bummer, this news really puts me in a bad mood.. But if there isn't any other way so be it. I appreciate your help let's hope now that buying a different controller will be enough.. do you have a preferable controller available in the EU ?

If it is compatible with the OSFW then you dont' need to rewrite the software, just change the settings appropriately, if the ahrdware supports it.

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I'm feeling dumb to ask this but where do you find the Open source Firmware because i don't find anything directly on the internet

I don't have a link, but you can look for the threads here on ES based on what I said above:

Another option is to checkout Casainho / Stancecoke /etc's Open Source Firmware OSFW thread(s), and see if yours is one of the compatible models, then try using the OSFW instead, which usually does allow quite a lot of customization of controller operation, as long as the hardware you have supports the function you want.

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The actual stuff is probalby on github or similar, but you should look at the threads themselves first for the links to the stuff you need, and the discussion about doing it to various controllers and displays.

It's also discussed right on that page you linked, where you got the schematic from. I think there are links too.


Also keep in mind that if you flash the MCU in your controller (with anything), and something goes wrong, you usually end up with a useless brick and have to go buy a new one. So if you need the bike you have to go places, I'd recommend keeping the stuff that works as it is, and get new stuff to experiment with. If it's all just an experiment, and not needed for riding, it's safe to do whatever you want to try out.

After some asking around on the internet someone suggested the MicroWorks 30B4 board, but this board is mostly used for unicycles or is it possible for this situation ?
Chancing the CPU of my KU63 could also be a possibility but i wouldn’t now which CPU
I think the KU63 motor controller is used as base for the open source ebike smart controller from Casainho so maybe i can do the same mods as him or is this too far fetched ?

Chancing the CPU of my KU63 could also be a possibility but i wouldn’t now which CPU

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I think it’s the STM8S105C6T6