Proportional braking/regen?

Hi there, sorry a bit new to this…. I’m working on an electric long john cargo bike build. I would like hydraulic brakes and have been looking at the Magura MT5E as a likely candidate.

That being said looking at its datasheet it looks to not have proportional signaling… Planning on using Grins Phaserunner, All axle motor, and Cycleanalyst for this build. Is proportional brake regen not a thing, or are there other parts I should be looking at?

Thanks!

Not sure I understand the question.

Variable regen braking involves only the motor as the braking element, not conventional brakes.

If you are looking to balance front/rear braking, I do not know of any direct system by which to achieve this. Unless maybe two motors, AWD, if the CA will handle this.

But to tie together hydraulic and electrical regen, don't think there is any system by which this could be achieved.

Once you have variable regen, then it get used for 90%+ of your braking work with the mechanical brakes used only at quite low speeds and for emergency stops. Then you recover as much energy as possible and the side bonus is that your mechanical brakes then need almost no maintenance.

WalkerYYJ said:

Hi there, sorry a bit new to this…. I’m working on an electric long john cargo bike build. I would like hydraulic brakes and have been looking at the Magura MT5E as a likely candidate.

That being said looking at its datasheet it looks to not have proportional signaling… Planning on using Grins Phaserunner, All axle motor, and Cycleanalyst for this build. Is proportional brake regen not a thing, or are there other parts I should be looking at?

Thanks!

Click to expand...

I think what you're asking is, "why does the Magura MT5E have an on/off switch (2 wires/pins), but the controller has variable regen (which requires a variable analog signal = 3 wires/pins)".

If you want variable regen, you'll need to install a hand control that can output a variable analog signal between 0-5V. Some (me) use a thumb "throttle" on the left side. Some make their own control by gluing a magnet and linear hall effect sensor on a brake lever. Or connect a "throttle box" by cable to a brake lever. Or, etc etc etc.

OR, it looks like the PR can use the throttle signal from variable braking (throttle becomes the brake control when you pull the brake lever).

Ya, you got it... Ok...

Any idea how "throttle" based regen is applied if you are using torque sensors?

Virtual coaster brakes would be great, ever been implemented?

WalkerYYJ said:

Ya, you got it... Ok...
Any idea how "throttle" based regen is applied if you are using torque sensors?

Click to expand...

No sorry. But I assume that if you don't have a throttle (torque only), then you'll have to add a brake control.

I have GMAC+PR. Variable regen is brilliant and as said earlier, mechanical brakes are very very rarely required. I control braking power with a thumb throttle mounted on the left bar.

Variable regen really is a lovely feature. I’m afraid I’ll never be happy on or in any EV that doesn’t have at least some form of regen control.

robby p said:

I control braking power with a thumb throttle mounted on the left bar.

Click to expand...

YOu can do it with a brake lever to make it more natural and instinctual, if you like.

After 1500 miles it has become about as natural as can be. Originally I thought I would want to have a proportional brake signal from the lever(s), but I rather like that the friction brakes are 100% not involved. The thumb throttle is inconspicuous and fits nicely between the brake & the grip.

I like Amberwolf's idea of replacing the rear brake lever with a lever used to control the regen on a variable regen set up, while leaving the front brake lever as normal. Different strokes....

Kinda like people driving their cars using their right foot for the brake vs. the left foot. I couldn't care less which you use. Just don't run over me or hit me in the rear!

Sorry if I didn't grok the details from the other thread

but is there a brake lever with a long enough pull and sensors accurate enough, that you could rig

First 40-50% of lever pull range does not engage hydraulics yet at all, use that for say the first 80% of the regen's range, then

have an overlap of the last 20% regen combined with a fast & strong mechanical ramp up

but not **so** fast that you put your tail up over your head

taking into account that in a panic stop you're just gonna haul back instinctively to full 100%

?

I'm with RobbyP. After using variable regen for an extended time, I want it completely separate from my mechanical brakes. Doing so maximizes the energy recovery and has made my mechanical brakes zero maintenance. I hate fiddling with any maintenance, and putting air in my moto tires every couple of months and checking battery balance 2-3 times a year pushes my limits. Good thing I don't care about my bikes getting a bit dirty, since they only get washed when overhauling, which should now be on a 5-10yr or more timeframe with my current rides.

If I can just figure out how to set up a solar powered automatic induction charging system for my bikes, so charging is just a matter of parking my bikes correctly. Then I'll be in hassle free transportation heaven.

Attempt at photo from mobile

AHicks said:

I like Amberwolf's idea of replacing the rear brake lever with a lever used to control the regen on a variable regen set up, while leaving the front brake lever as normal.

Click to expand...

The idea isn't to replace the rear brake that way...it's to add the regen to whatever existing braking there is. In the case that I show in that thread, I don't *have* a rear mechanical brake yet, so using the cable for the proportional regen "throttle" was an easy solution.

But as I think I noted in that thread, they make dual-pull brake levers, so that one can be used for the mechanical brake, and the other for the electronic one. Each can be adjusted so that the regen pulls most of it's range before the mechanical begins to really pull, depending on the amount of cable travel the lever allows vs what's needed to engage the mechanical brake. If necessary, a Travel Agent or similar can be used on the mechanical one so taht once it does begin to pull, it pulls quickly to it's full engagement, since it's only needed for that kind of braking anyway, for when the regen isn't sufficient or isn't working.

robby p said:

After 1500 miles it has become about as natural as can be. Originally I thought I would want to have a proportional brake signal from the lever(s), but I rather like that the friction brakes are 100% not involved.

Click to expand...

The only reason I suggest it is that if you're in an emergency stop, and the regen brakes are either not enough, or somehow stop working, there isn't time to move one's hand to the mechanical brake, but there is time to simply squeeze a lever further.

While (like a battery fire) it is a very low-probability event, it is a very high-consequence one.

amberwolf said:

AHicks said:

I like Amberwolf's idea of replacing the rear brake lever with a lever used to control the regen on a variable regen set up, while leaving the front brake lever as normal.

Click to expand...

The idea isn't to replace the rear brake that way...it's to add the regen to whatever existing braking there is. In the case that I show in that thread, I don't *have* a rear mechanical brake yet, so using the cable for the proportional regen "throttle" was an easy solution.

But as I think I noted in that thread, they make dual-pull brake levers, so that one can be used for the mechanical brake, and the other for the electronic one. Each can be adjusted so that the regen pulls most of it's range before the mechanical begins to really pull, depending on the amount of cable travel the lever allows vs what's needed to engage the mechanical brake. If necessary, a Travel Agent or similar can be used on the mechanical one so taht once it does begin to pull, it pulls quickly to it's full engagement, since it's only needed for that kind of braking anyway, for when the regen isn't sufficient or isn't working.

Click to expand...

My apologies. Didn't mean to put words in your mouth, I just lightly scanned the note, filing the potential for using a hand lever control for regen away for future use. I like that idea, and will likely be putting it to work when I get around to doing mine.

Not to take away from the potential for a dual pull rear brake lever, as dual pull is certainly an option, but syncing the regen to the rear brake application in an effective manner might be a bit tricky, no?

I suppose in a worst case scenario, in the case of a regen failure, with dual pull you would then have full use of a conventional rear brake for back up. That's not a bad thought either.... -Al

Being strongly right handed, if I set up that way, should the hydraulic lever be there?

Getting "precise" control on the regen not being so critical?

Double pull would allow for both front and rear mechanicals to work off the one handle, and the adjustability between them to ensure a good balance in a panic-stop.

AHicks said:

Not to take away from the potential for a dual pull rear brake lever, as dual pull is certainly an option, but syncing the regen to the rear brake application in an effective manner might be a bit tricky, no?

Click to expand...

Well, it depends on how you want the system to behave. If you are syncing them, to add regen to the mechanical to just make it stronger thru the whole range, you'd have to have a regen braking torque curve that matches your mechanical braking torque curve. Some controllers, like the Lebowski brain, have adjustable curves, so you could probably do that easily. Others don't, so would be dependent on the curves, or creating electronics to let you change the curve of the COT unit used for the ebrake.

But in my case, using regen *first*, and never activating the mechanicals unless more braking is needed than the regen can provide (or that fails), adjusting cable tensions separately with the dual pull lever should allow regen to max out before mechanicals begin to engage, or at least have minimal overlap.

If overlap would otherwise be too great, then the mechanical cable tension would be left looser, and a Travel Agent pulley (or similar) could be used to double the pull of the cable, so that when it does start to engage, it engages twice as fast, so it will still give max braking before lever pull is maxed out.

Additionally, the throttle curve can be changed in the Lebowski brain I"ll be using, to allow forcing the ebrake to max out sooner than it otherwise would, to also minimize overlap.

It's an experiment still to be done, so can't yet say if it will do what I want.

I suppose in a worst case scenario, in the case of a regen failure, with dual pull you would then have full use of a conventional rear brake for back up. That's not a bad thought either.... -Al

Click to expand...

Yes. In my case I'll have the rear brakes regen and mechanical on the left lever, and then *also* have the rear regen with the *front* mechanical brake lever on the right. This may also end up with an override switch, to allow for *just* using the mechanical front if I can determine any situations that would warrant that.


At present, I'm testing out an ATV thumb-throttle (cable operated, using another of the COT hall-based throttle units just like that used for the regen lever) on the right, and it has a dual-pull lever integrated into it (with a brake light switch as well). Unfortunately it's the wrong amount of cable pull for my Avid BB7 MTN brakes, so I'll have to use a Travel Agent or similar pulley to use it for the mechanicals (so at present the lever itself is not attached, and I'm still using the Avid single-pull lever). Details on that are over in the SB Cruiser thread.

If I was using the BB7 Road version, or some of the drum brakes, it would probably work fine without this. So the ATV lever would likely work for a number of bike builds that also could use proportional regen.