E-brakes built into the controller?

[BIG BEAM]

Why hasn't anyone built electric brakes into a controller?It would eliminate brake service for one wheel.They've been doing it in R/C for years.I know the regen would be very little but still it would be some.Seems like a win win thing to me.But I am a noob and might be missing something simple.
DON

 

[Jeremy Harris]

They have. All the cheap Xiechang/Infineon controllers have a regenerative braking function built in. It can work in a couple of ways and is user programmable via the programming interface.

Jeremy

 

[amberwolf]

Just remember that any form of regenerative ebrake on a permanent magnet motor has the opposite performance curve of a mechanical brake--it performs better the faster you are going when it is applied, and worse the slower you get, until at some point it no longer provides any effective braking. Certain things a controller can do will extend the bottom end of that curve farther down, but it still doesn't work when nearly stopped and actually stopped.

Mechanical brakes do the opposite--they work less well at high speed, but at low speed or stop they can work so well that it could take so much force to turn the wheel that the tire could be destroyed before the wheel will turn (or in the case of disc brakes, the spokes may stretch and break before the disc breaks friction lock).


Also, at high enough speeds to work, regen ebrakes act like disc brakes do, regarding the tension against the wheel, assuming you have sufficient torque arms installed to properly transfer the braking force to the fork from the axle. If you don't have a good torque arm setup on the axle (preferably both sides), you may rip the axle out of the dropouts when braking from high speeds with ebrakes, as that braking force could be many times the possible startup force of the motor, depending on the controller's braking design and the battery's ability to soak up the current (or the plug-braking load's ability to dissipate the power without melting).

 

[BIG BEAM]

Yeah but couldn't it be built into the brake lever (proportional)like they do with R/C.Then the rider would take into account the force it creates (hi speed vs low speed braking).
DON

with simple regen you have little control over the braking affect.

 

[amberwolf]

Ah, that's a different question!

That can be done, and some do have this ability (though they usually do it by activating it with the lever and then having throttle control amount of regen).

I have an untested idea of PWMing the brake input, using a linear hall (or a pot) to replace the switching one in an ebrake lever, but if the controller has any noise filtering in place for the brake line, it probably won't work, without removing that filtering. If the filtering is electronic that's easy, but if it's in software...we don't have the source code to rewrite and reflash the MCUs in the controllers with. Someone would have to write new controller code entirely from scratch, which I can't imagine happening just for this.

 

[Jeremy Harris]

Yeah but couldn't it be built into the brake lever (proportional)like they do with R/C.Then the rider would take into account the force it creates (hi speed vs low speed braking).
DON

with simple regen you have little control over the braking affect.

Not too hard to do. The brake lever switches could be replaced with a linear Hall sensor, like the throttle uses, and this could be switched into the throttle line when braking. Alternatively, I believe that there is an option to use what feels like engine braking, where closing the throttle applies a variable amount of regen depending on the throttle setting. I've not tried it, but seem to recall seeing a post here where someone had.

This gives a reasonable solution, as you can finely control the amount of regen braking by just limiting the throttle movement and without needing to touch the brake system. The only thing to watch is the brake balance. If you have a rear wheel drive system then using large amounts of regen braking might not be a wise thing to do.

Jeremy

 

[BIG BEAM]

Like anything I'm sure people will get used to it(as long as a standard in used and all controllers do it the same)Another idea is to spring load the throttle so that one way you have proportianal throttle and then if you let go it will go to neutral(coast) and twist it the other way and the more you twist it backwards the more brake it applies.Just thinking out of the box here.
DON

 

[DAND214]

And then you push it further and back into your parking place?? Just kidding. :lol: i have the regen braking and yeah as you slow down the brake gets weaker. Then you use the brakes to stop and or hold you in place on a hill.
Dan

 

[Hillhater]

sure its technically possible and theoretically a smart thing to have... but..
..Ask yourself if regen braking is really necessary or beneficial.
what exactly would it add that you dont already have, and what problems may it introduce that you dont want . :wink:

 

[fechter]

I used regen on my Zappy scooter. The mechanical brakes on those really sucked, so having regen helped immensely on long steep downhills. Mine was set up with a limiter circuit that kept the regen force constant regardless of speed until it got down to crawling speed, then it gave out. I had to adjust the limiter to keep the belt from skipping teeth, which was the limiting factor. This also prevented the rear wheel from skidding.

Most of the chinese controllers don't have a very sophisticated regen setup so its not as useful as it could be.

To me, ideally the regen would ramp up you barely touch the brake lever and reach a maximum that would stay constant with speed change like my Zappy's. If the maximum is set properly, you can avoid excessive component stress and heating.

One thing to also keep in mind is that the motor will be generating heat during regen as well as during acceleration, so motor heating can become an issue.

The amount of energy recovered is pretty pathetic on a typical bike setup (something like 25%), but having brakes that don't fade on a long hill can be pretty important. If you live in the flatlands, its most likely not worth the bother.

 

[Hillhater]

The amount of energy recovered is pretty pathetic on a typical bike setup (something like 25%), but having brakes that don't fade on a long hill can be pretty important. If you live in the flatlands, its most likely not worth the bother.

I suspect that 25% is a maximum .!
I am no expert on this, but i have discussed with professionals in this field and they are adamant that regen is hardly ever worth the extra cost of the installation. 8 -10% energy recovery is typical even on the best commercial applications (those big mining dump trucks)... but the braking effect is absolutely essential for them as mechanical brakes are cactus after only a few hours without it.

 

[adrian_sm]

I use regen, and only get about 4% on my daily commute.

On a light electric vehcicle like ebikes, most energy is lost to wind drag, not the lose of kinetic energy to heat of start stop braking.
In a car, or even a motorbike the percentages will go up.

)Another idea is to spring load the throttle so that one way you have proportianal throttle and then if you let go it will go to neutral(coast) and twist it the other way and the more you twist it backwards the more brake it applies.Just thinking out of the box here.
DON

That is exactly how the Vectrix scooter works. It has a throttle that rolling back applies throttle, rolling forward applies regen.
Very nice set-up IMHO.