Recreating the Model S braking system

[bronz]

Hi, I'm relatively new to the forums and e-bikes. I am wondering how regenerative braking is normally set up. From what I have seen lurking around, normally a special brake lever is used to engage the regenerative mode of the controller and is called the "e-brake." Has anyone heard of setting up a throttle so that it engages regenerative braking as soon as it's closed? The Model S does this, activating regen' braking whenever the gas pedal is not depressed. I think it's a good idea so I would like to get some feedback about it before I try to implement it in something I build. Has anyone used a setup that does this?

 

[tony67]

My lyen edition infineon controller does this. I think all infineon controllers have this ability. It is enabled by connecting the white wires together. As energy recovery it is not very effective, usually achieving under 5% regen but it will reduce wear on brakes.

 

[wesnewell]

You can do it, but it's not commonly implemented that way.

 

[Punx0r]

Automatic regen works in a car, but on a bicycle you often have to release the throttle to indicate/signal...

 

[Wheazel]

Sure it works, but consider this:
In a traditional car you actually transform quite some kinetic energy to heat in the brakes when braking. (Energy that can be used for regen with conversion losses) Good aerodynamics relative to the mass.
On a bike almost all energy is wasted to move the surrounding air. Very little energy actually goes into the brakes. Bad aerodynamics relative to the mass.
This means there is not as much to gain on a bike compared to a car for identical systems.

 

[wineboyrider]

I use regen on both of my Direct Drive bikes with lyen controllers, only because it's less wear and tear on the brakes and rims. I also, like the feel of the regen as it slows the bike very smoothly.

 

[amberwolf]

Has anyone heard of setting up a throttle so that it engages regenerative braking as soon as it's closed? The Model S does this, activating regen' braking whenever the gas pedal is not depressed. I think it's a good idea so I would like to get some feedback about it before I try to implement it in something I build. Has anyone used a setup that does this?

If you don't want to coast, ever, then I guess that would work, but if you like to coast along for any reason, you would want a separate button to do it instead.

Or set it up like the Vectrix (at least some of them?) where throttle in one direction controls power, and the other direction controls braking.


In a car it seems like few people ever bother to try to coast down the road, so a system that doesn't allow it might be ok, but in a bicycle where coasting is often desirable, I think most poeple would prefer the ability to do it. Up to you if you need it or not.


Since any existing bicycle rider (presumably including yourself?) already is trained to "instinctively" use the brake levers to slow down, it's probably a better idea to simply add a switch to your existing levers, cables, or arms to engage the regen in the controller (assuming you don't want to replace your levers with teh crappy ones that come with most kits).

Or if you want proportional regen braking instead of on/off, get a controller like the one in development at Grin Technologies (ebikes.ca) recently posted about here on ES (yesterday?) and use an analog sensor on your levers/cables/arms/etc for that. There are probably other controllers that do proportional regen, besides the expensive ones like Sevcon, but most ebike controllers do not--they have braking that is either on or off.

 

[bronz]

Thanks for this feedback guys, it's very helpful.

 

[xenodius]

The adaptto controller also allows for proportional regen from a hall signal with programmable ranges =) It'd be very easy to wire up a custom lever for that. In my case, I'm on a tadpole-- I need individual front brakes so I can properly brake on high speed turns (more brake on outside wheel, so I don't lose traction) and so I would need three levers, which I don't want. So I'm going to use an extra thumb throttle for e-braking. I plan on setting it fairly high, on an exponential curve... that way I should be able to skid my rear wheel if I want to. =D

 

[Chalo]

So I'm going to use an extra thumb throttle for e-braking. I plan on setting it fairly high, on an exponential curve... that way I should be able to skid my rear wheel if I want to. =D

E-braking is inherently anti-lock, because back EMF approaches zero as RPM approaches zero. That's not to say you couldn't skid a bit if your road speed and braking demand were both high.

 

[amberwolf]

Although if you choose to use Plug braking (directly shorting the windings) instead of typical regen braking, or some form of active braking that actually reverses power flow thru the motor to counter it's forward rotation, then you probably could skid the wheel easy enough--but neither one is a standard feature of any typical ebike controller I know of.


I think there is a moped/scooter posted about in the last couple weeks that does have the active braking, though. Can't remember the name, but it's claimed to be "made in usa".