how to make a proportional / variable regen ebrake brake lever

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how to make a proportional / variable regen ebrake brake lever

Post by amberwolf » Apr 03 2020 3:51am

this project is for those that don't want to use a throttle to control braking force, and prefer a brake lever (perhaps because it is what you're already used to on a bicycle for braking, and if you've ridden as long as i have, it's so hardwired it could take years to change the reflex action. in the meantime, you're left with the dangerous possibility of indecision or using the wrong control or the right one in the wrong way, in an emergency situation.)



this can be used in the simple way for any controller with an independent analog ebrake input.

this can be used in the more complex way for any controller like the phaserunner and present grinfineons that come setup with a single analog (throttle) input, which responds to voltage range below normal throttle outputs as proportional regen braking, if you use a cycle analyst v3 as well.

there is an even more complex way that i havent' developed and tested yet, to directly control the pr/gf without a ca v3; this requires voltage translation electronics to change the throttles upward-going voltage range to a downward going voltage range that is much smaller.




simple way:

you'll need a regular cable-style brake (or ebrake) lever, but with no mechanical brake cable attached to it. if you use an ebrake lever, you can then use the switch in it to activate brake lights, either directly for low-current units, or remotely via relay for incandescent/etc. a scooter or motorcycle lever will also have a switch in it that is designed to switch the brake light on when pulled, so you can use these too. mount this to your bike wherever you prefer to use it. if you already have both a left and right brake lever that control mechanical brakes, you may either have to put this "behind" one of them, or figure out a way to split the cable from it to both the mechanical brake and the cot (see below). that's not covered here.

you'll need a cable-operated throttle mechanism (cot). some of these are hall output, and some are potentiometer. as long as your controller supports the full voltage range on it's independent analog brake input, it doesn't matter which one you use. the cot should come with a cable, housing, and adjusters; the adjuster end should have a cable end that will fit in your brake cable holder of the brake lever. if it doesnt', you'll have to change the cable to a regular brake cable, and come up with a way to fasten it to the cot's pulley, if it doesnt' already have the correct knob at that end.
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mount the cot unit wherever you prefer; if it's not weatherproof it should go inside whatever *is* weatherproof on your bike or vehicle.
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the cable most come wiht is pretty short, so you might have to replace that cable and housing with one that is long enough to reach the spot you want it to go. you may also have to change the adjusters to fit your brake lever, unless you just use a regular brake cable and housing, and use the adjusters already on the lever. the adjusters on it are not meant for brake levers, but for cable-throttlegrips, so it's unlikely the threading and size will "just fit" your brake lever.
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the electrical cable is also pretty short, and probably has a tamiya or similar plug on it; this probably wont' fit whatever controller you're using, so you'll have to fix that, too, while you're splicing on a longer cable. so far the ones i've seen use red for 5v, black for ground, and green for the signal output. wire these up to the appropriate pins on your controller's analog brake input.

every controller's setup program and method is different, so none are covered here. but you'll need to set up that input for the voltage range you actually get out of the cot, for the range of travel you get out of the lever for the braking movement you prefer. it's possible that the cot wont' pull it's full range for the amount of lever travle you can get. in my case, i got exactly the full cot range for the full lever range; i doubt that will happen for every cot and lever combo.


once it's setup, all you have to do to engage braking is to use the lever naturally.

there may be controllers that require you to engage a brake switch at the same time or before sending the control voltage to the analog brake input. if so, you can use an ebrake lever and use that switch to do this.

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Re: proportional regen ebrake lever

Post by amberwolf » Apr 03 2020 4:00am

note: this post is still a work in progress and will be edited as i doze and wake and get all the details lined up.



complex way:


you'll need a common (wuxing, etc) cable-style ebrake lever, but with no mechanical brake cable attached to it. the ebrake switch should be the type that closes (or grounds) only when the lever is pulled. (you could use the other kind, but you'll need to work out your own additional circuit to invert the operation of the relays). a scooter or motorcycle lever will also have a switch in it that is designed to switch the brake light on when pulled, so you can use these too.

mount this to your bike wherever you prefer to use it. if you already have both a left and right brake lever that control mechanical brakes, you may either have to put this "behind" one of them, or figure out a way to split the cable from it to both the mechanical brake and the cot (see below). that's not covered here.


you'll need a cable-operated throttle mechanism (cot). some of these are hall output, and some are potentiometer. as long as your controller supports the full voltage range on it's independent analog brake input, it doesn't matter which one you use. the cot should come with a cable, housing, and adjusters; the adjuster end should have a cable end that will fit in your brake cable holder of the brake lever. if it doesnt', you'll have to change the cable to a regular brake cable, and come up with a way to fasten it to the cot's pulley, if it doesnt' already have the correct knob at that end.
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mount the cot unit wherever you prefer; if it's not weatherproof it should go inside whatever *is* weatherproof on your bike or vehicle.
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the cable most come wiht is pretty short, so you might have to replace that cable and housing with one that is long enough to reach the spot you want it to go. you may also have to change the adjusters to fit your brake lever, unless you just use a regular brake cable and housing, and use the adjusters already on the lever. the adjusters on it are not meant for brake levers, but for cable-throttlegrips, so it's unlikely the threading and size will "just fit" your brake lever.
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the electrical cable is also pretty short, and probably has a tamiya or similar plug on it; you can cut this off because you're going to connect it to the relay for the signal wire, and the ca v3's 5v and ground for the other two, while you're splicing on a longer cable (if you need more length). so far the ones i've seen use red for 5v, black for ground, and green for the signal output.



you'll also need at least one relay. if you have a 12v source for lights, etc., then use relays with a 12v coil. if you don't, you'll need to use the 5v from the ca or the controller, so get a relay that has a 5v coil, and that uses as little current as possible to pull the coil in, so you don't strain the ca or controller's 5v supply. or youll need to use a relay that has a coil that runs on the same range of voltage as your main battery (might be harder to find in something really tiny). the relay needs, at minimum, to be an dpdt / 2p2t, so it has a common and a normally open and a normally closed for each of two separate independent switches inside. one of those is to switch the throttle signals, and the other is to engage the ca's ebrake signal.

i used three spdt relays because i had them out of an old dead ups board. in my case i also have a brake light, so the last one is used to turn that on at the same time.
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note that you're going to have to modify the wiring from your existing throttle (if any) to your cycle analyst v3. if you don't have a throttle, and are only using pas (cadence or torque) you don't need the relay for this, and can skip those steps, in this case, you wire the cot wires all directly to the ca v3's throttle input connector. and the ebrake switch directly to the ca v3's ebrake input connector, as normal.


if the ebrake switch is a two-wire switch, then one wire connects to one of the coil pins. the other wire connects to the voltage that coil needs (5v, 12v, or main battery voltage). don't use the wrong voltage, as it will either burn up the relay or make it not reliably switch on. the other coil pin is wired to the ground for that voltage source. when you pull the lever, the relay should click on.


the common pin of the relay is wired to the cycle analyst v3's throttle input connector, it's signal pin. the normally closed nc pin of the relay is wired to the regular throttle's signal output pin. the normally open no pin of the relay is wired to the cot's signal output pin.


the cot's 5v and ground wires are wired to the same points as the regular throttle 5v and ground wires. you can either modify your existing cabling, or make jst (or higo, etc) cables to match your existing wiring setup, to "y" the two throttles and the relay to the ca v3's throttle input port as plug-n-play.


don't test any of the stuff above without the bike / vehicle's powered wheels offground. if you've left out a ground or miswired something, you could get full throttle and that's no fun at all when you're not actually riding the bike. ;)



in the ca v3 setup menus, there is a brake section. enable prop regen, and assuming you're using a phaserunner setup as normal factory settings, or a grinfineon, setup the voltage for 0.8v. it may change to 0.79 automatically when you save; that's normal afaict.

now the ca will automatically change modes when the brake lever is pulled, so that throttle input in a normal range (whatever you've already setup in the throttle input setup menus) will cause the throttle output to send a 0.8v signal to the controller as you start braking, down to 0.0v as lever pull reaches max. the grinfineon/pr will respond by a little regen braking for a little lever pull, or max regen braking for max pull (as long as the lever pull range causes the cot to output a compatible voltage range with the throttle input settings youv'e chosen).
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you may need to determine the voltage range you actually get out of the cot, for the range of travel you get out of the lever for the braking movement you prefer. it's possible that the cot wont' pull it's full range for the amount of lever travle you can get. in my case, i got exactly the full cot range for the full lever range; i doubt that will happen for every cot and lever combo. if you don't get enough voltage for the full range, you would have to change the ca v3's throttle settings (not desirable as it also affects your actual throttle) or you would have to build scaling electronics to compensate, or use something like the travel agent pulley that's designed to compensate for the wrong lever on the right brake / etc for road vs mountain bike levers. if it does what you want without this, you're set. if not, you'll have to decide whihc of these ways works best for you.


once it's setup, all you have to do to engage braking is to use the lever naturally, and youll get electric braking that increases force with lever travel.

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Re: how to make a proportional regen ebrake lever

Post by SlowCo » Apr 03 2020 1:56pm

Great work and thanks for making this tutorial :thumb:

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Re: how to make a proportional regen ebrake lever

Post by rowbiker » Apr 03 2020 6:37pm

Well done, amberwolf. A very useful addition to making ebikes safer and more fun.

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Apr 04 2020 10:53pm

thanks...it's not done yet, but what's there is usable by anyone that wants to do it. :)

eventually i'll get something more refined worked out and posted, but if that never happens, at least this is up now.

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Re: how to make a proportional regen ebrake lever

Post by j bjork » Apr 08 2020 6:01am

Would it not be easier to use a hydralic brake handle, and mount a pressure sensor on it?

So when you press the handle, the pressure goes to the sensor. The harder you press, the higher the output. I have not tested it yet, but I think it should give a natural feeling too.

I dont know how high the pressure is in bike brakes thogh? (To choose the right sensor)

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Re: how to make a proportional regen ebrake lever

Post by Nixunen » Apr 08 2020 6:16am

j bjork wrote:
Apr 08 2020 6:01am
Would it not be easier to use a hydralic brake handle, and mount a pressure sensor on it?

So when you press the handle, the pressure goes to the sensor. The harder you press, the higher the output. I have not tested it yet, but I think it should give a natural feeling too.

I dont know how high the pressure is in bike brakes thogh? (To choose the right sensor)
I made variable regen brake lever using my Hope tech 3 lever and linear hall sensor + magnet. Now when i pull that rear brake lever. first it uses variable regen, and there is free movement in lever, so i can pull lever some distance before pistons / brake pads start moving. So if i want i can use only regen, and if it is not enough i just pull more and it start to use normal rear brake

Voltage goes about 0.10v to 2.5v (2.5v when lever is completely pulled, also there is possible to adjust that, just simple turning that screw more open or more close (tip of screw move either further or closer to sensor and that adjust how long that movement in lever need to be)


This is how i do it I remove bite point adjustment screw out of lever and replace it with steel screw (because it is magnetic). Then i cut that screw down and place top of it little magnet.

There is picture about that screw (before cutting down) also there is that hall sensor taped for testing.
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Next thing was using dremel and take little bit material of end of lever, so there is space for hall sensor
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I glued hall sensor under that bite point adjustment screw (using strong epoxy) and same epoxy i used to glue magnet top of that steel screw. There is one picture for it
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There is also short video when i was testing it. I am sorry that audio is Finnish language, but this time i don't want to make another English language video. But there can see how it work (watching multimeter voltage display, so ti acts just like throttle etc, just need to connect regen brake port. And if i change that magnet another way, then voltage goes high to low, about 4.7v to 2.5v but i want to use it like this, so it goes low to high)

[youtube]jRieAlAamV0[/youtube]
Last edited by Nixunen on Apr 08 2020 1:33pm, edited 2 times in total.

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Apr 08 2020 12:05pm

j bjork wrote:
Apr 08 2020 6:01am
Would it not be easier to use a hydralic brake handle, and mount a pressure sensor on it?
if you have hydraulic brakes, it might. *** (see below) ***

but most people don't, and there's not usually much reason to change the entire brake system just to get this feature. ;)

(or to have to learn how to install and bleed them, which you'd have to be able to do to install such a sensor in the hydraulic line of an existing system, or else take it to a shop to have them do that, if they're willing to.)

(as an example, the cable-operated avid bb7 disc i use works perfectly fine to skid the wheel for the sb cruiser trike, with minimal lever effort. a different system is completely unnecessary. ;) )


*** caveat: as long as the sensor outputs something within the same range as your throttle's output range (and definitely within the 0-5v range max), if using a cycle analyst to do the prop regen translation for controllers with only one analog input, because the ca will be using the same range settings for your regen throttle (the cot/lever) as it does for your actual throttle. if the range is greatly different, the ca will not correctly translate the full movement range of the lever into the 0.8v to 0.0v range required for the prop regen throttle input range of controllers setup to do this. (the ones that aren't programmable like the phaserunner is).


if using the sensor on a completely separate input, then it doesn't matter what it's range is as long as the controller's separate analog brake input will take that voltage range and is programmable to react to it the way you need it to.




another issue is that you will also be applying your mechanical brakes at the same time as the ebrakes, instead of being able to use them separately, unless you have a pressure sensor that is *very* sensitive, such that it's full output range is for a very small pressure change, such that the entire range is used before your mechanical brakes begin to apply pads to rotors. that might be a little more sensitive than some (most?) people would want, though i expect it'd be easy enough to retrain the hand to use them adequately.

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Apr 08 2020 12:07pm

Nixunen wrote:
Apr 08 2020 6:16am
There is picture about that screw (before cutting down) also there is that hall sensor taped for testing. Bigger pictures if you click them.
since the pictures do not show up for me (and probably for some others), and so they cannot be lost if the external site ever goes down, would you please attach them directly to your post using the attachments tab instead? this uploads them directly to the es forum server, so that anyone that can see the post can see the pics, and they are stored and backed up with the post itself.

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Re: how to make a proportional regen ebrake lever

Post by j bjork » Apr 08 2020 12:50pm

I don't mean that you should have to change the hole system, or connect it to the line and use it with the mechanical brake. I mean just use the handle and the sensor instead of the brake line.
And use a sensor that put out 0-5v, maybe something like 40bar for max output. (or what pressure you get when you pull the lever hard)

Then it would not be a matter of pulling the lever to the point where you get the brake power you want, instead pull as hard as needed. Just like normal breaks, I think it would be much more natural.

I think in your solution when you should pull the lever the right amount and not to far, you will lock the wheel in a stressful situation.

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Re: how to make a proportional regen ebrake lever

Post by Nixunen » Apr 08 2020 1:27pm

amberwolf wrote:
Apr 08 2020 12:07pm
Nixunen wrote:
Apr 08 2020 6:16am
There is picture about that screw (before cutting down) also there is that hall sensor taped for testing. Bigger pictures if you click them.
since the pictures do not show up for me (and probably for some others), and so they cannot be lost if the external site ever goes down, would you please attach them directly to your post using the attachments tab instead? this uploads them directly to the es forum server, so that anyone that can see the post can see the pics, and they are stored and backed up with the post itself.
Sorry, i didn't know that pictures not show. Because it show them fine with my screen. But now those are fixed.

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Apr 08 2020 5:55pm

j bjork wrote:
Apr 08 2020 12:50pm
I don't mean that you should have to change the hole system, or connect it to the line and use it with the mechanical brake. I mean just use the handle and the sensor instead of the brake line.
ah, well, you'd still need to setup the "complete" lever/mastercylinder and perhaps a bit of line to the sensor, unless the sensor can be directly installed into the mastercylinder. i'm not sure how to bleed the system (or if it needs it) if setup this way?

but that might be smaller and "cleaner" install than the regular lever and cable operated throttle assembly (the cot i have is almost as big as the palm of my hand). possibly more waterproof; i don't know how weather resistant the cot i have is.


And use a sensor that put out 0-5v, maybe something like 40bar for max output. (or what pressure you get when you pull the lever hard)

Then it would not be a matter of pulling the lever to the point where you get the brake power you want, instead pull as hard as needed. Just like normal breaks, I think it would be much more natural.
it would certianly be an interesting experiment. if i had lever/mastercylinder parts to do this with (other than some large motorcycle stuff of unknown condition) and a sensor, i'd try it out.

I think in your solution when you should pull the lever the right amount and not to far, you will lock the wheel in a stressful situation.
if you mean with the regular lever and cot, that's certainly possible, if you've not practiced "panic stops" so you won't react that way, becuase the lever doesn't have as much resistance as a mechanical brake. that could be fixed by adding a pull spring to the lever with sufficient tension to give the force desired. (or increasing the force of the internal spring of the cot to this degree).

it also depends on the amoutn of force your regen can provide--most controllers cant' create enough regen current to lockup the wheel.

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Apr 08 2020 5:57pm

Nixunen wrote:
Apr 08 2020 1:27pm
Sorry, i didn't know that pictures not show. Because it show them fine with my screen. But now those are fixed.
thank you--that's a pretty neat setup, now that i can see it. :)


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Re: how to make a proportional regen ebrake lever

Post by SlowCo » Apr 18 2020 5:50am

That seems to be a very heavy and overkill solution to "only" get regenerative braking. I like the pressure transducer idea when put inline with a normal hydraulic brake system.

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Re: how to make a proportional regen ebrake lever

Post by j bjork » Apr 21 2020 7:18am

That is exacty what I was talking about. Interesting to be able to make a 15min video of a simple solution :)
SlowCo, yes it is a bit bulky. It will be smaller if you use a bicykle handle. It sure can get smaller if you build something from scratch, but a lot harder.

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Jun 06 2020 12:27am

I found another brake lever unit that is useful for this:

https://www.amazon.com/gp/product/B07GF9V6X7

which also has a thumb throttle that pulls a cable, so should be usable with one of the cable-operated throttles to move that off the handlebars.

The whole unit is made of metal, so less likely to break the thumb tab off like so many before it.


The lever is dual-cable-pull type, separately adjustable for tension. However, they're for "ATV drum brakes" rather than bicycle disc or rim brakes, so probably don't have the right pull amount to work with those, like the Avid BB7 disc brake on the trike's front wheel


The main thing, though, is to use it with the COT unit as noted in this thread, for proportional regen braking. Having the second, separately-adjustable, cable pull is just a bonus. ;)

It also has a brakelight switch built in, so you can use that for brake lights or for the relay engagement like I did, etc.

If this does work with the BB7 cable disc brakes (even if it requires a pulley to change advantage ratio), then it would let me control the ebraking from it at the same time as the regular braking--and be able to even setup the regular braking to not start until after the regen braking has already progressed to significant levels.

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Re: how to make a proportional regen ebrake lever

Post by john61ct » Jun 06 2020 1:32am

For me, I see proportional regen braking as "drag braking", preventing excessive pad wear and supporting controlled long descents and steep grades

completely separate from safety in emergency stop hard-braking.

I certainly would not want the latter to depend on the former

nor allow any delays for any reason

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Jun 06 2020 3:59am

Note that this is OT for this thread, which is a how-to, not a discussion on types of braking, but I'll answer it here to prevent spread of misinformation.




Proportional (variable) regen is is *controllable* regen, which means you can modulate your braking just as you can with mechanical brakes, and control your deceleration (emergency or otherwise). So you can have braking as powerful as your motor/controller/battery system can support, which can be setup on some of them to be greater than the motor acceleration capability, enough to lockup the wheels.

Without that, you only get on/off regen, which means you have no control at all over it--you just get what you get as soon as you engage the switch. So if you set it up for hard braking force, enough to potentially skid your wheel like a mechanical brake should have, then you may just lock up your wheel, and be unable to modulate braking, and perhaps just crash.

If you don't have strong regen then it's not much good as an emergency brake and you'll have to use mechanical brakes anyway.

And in an emergency it's usually a bad idea to slam on your brakes all the way anyway, as that often loses you control of the situation, especially if it's your steering wheel doing the braking.



Additionally, if you have strong regen and you only have on/off control over it, the slamming on each time is hard on your motor's axle and mounting system, and with the cheap components and manufacturing processes often used, even with careful attention to mounting, can result in broken axles (or mounting systems), and destroyed wiring, etc. (and broken faces if it's on the front wheel).

If you have proportional control over it then you don't have to slam it on even in an emergency stop, so you can be much easier on your hardware.


There are additional considerations depending on the electrical system as well, but those get complex due to the myriad variations so not going into them here.

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Re: how to make a proportional regen ebrake lever

Post by john61ct » Jun 06 2020 11:44am

And personally, the actual-hard-stop braking to be used in an emergency, should not depend on complex electronics to work

nor any "higher-level" thought process, rely on instinctive lizard-brain reflexes only.

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Re: how to make a proportional regen ebrake lever

Post by NCC1941 » Jun 06 2020 5:35pm

john61ct wrote:
Jun 06 2020 11:44am
And personally, the actual-hard-stop braking to be used in an emergency, should not depend on complex electronics to work

nor any "higher-level" thought process, rely on instinctive lizard-brain reflexes only.
I can understand the thinking behind the first part. But what could possibly be more instinctive, on an ebike, than having brakes happen when you squeeze a brake lever?
"The Kitchen Sink" - 2016 Surly ECR 29", 2WD Grin All-Axle + 9C RH212, 2x Phaserunner, 52v50Ah EM3ev (Rolling WIP)
"Novara Barrow eBike" - 2016 Novara Barrow Bike, Luna BBS02, 52v28Ah EM3ev (Retired)

john61ct   100 GW

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Re: how to make a proportional regen ebrake lever

Post by john61ct » Jun 06 2020 7:21pm

Sure if that's how you get yours to work.

Others have a separate control, even a dial pot.

My point is, the mechanical braking side of what happens when you pull / squeeze should be enough to do the job on its own, even if the regen stops working completely.

IMO.

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Jun 06 2020 7:36pm

You're completely missing the point of this whole thread. :roll:

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Re: how to make a proportional regen ebrake lever

Post by amberwolf » Jun 09 2020 4:21am

amberwolf wrote:
Jun 06 2020 12:27am
I found another brake lever unit that is useful for this:

https://www.amazon.com/gp/product/B07GF9V6X7
Some pics of this unit at the end of the post.

It's definitely all metal, and fairly heavy--have to weight it, but perhaps a pound and a half. Not exactly precision-machined or a well-designed casting, but it doesnt' have sharp edges or obvious problems, other than the brake lever itself being rather floppy, with no bushing/etc in the pivot. Not a big deal.

It does have one more feature I couldn't be certain of, just looking at the pics online, but suspected: a "parking brake" lock pin. While pulling the lever back, push the pin down, and it will lock the lever back to that position. That's a feature I've been wishing for enough to have already worked out a way to add it to my existing brake levers, but not yet gotten around to building. (lot of work).

There is also another feature I couldn't be certain of, a throttle-limit adjustment screw. Running it out lets you push the thumb tab in further, running it in limits how far you can do so. This could be used as a top-end limiter for controllers that don't have a way to adjust max throttle input, if you needed to do so fro some reason, or to match your throttle's max output to the controller's max input, if for instance the throttle was capable of a high enough output voltage that the controller would error out (rare, but possible).


The dual-pull cable uses a floating-pivot for the cable-stop holders. There's a bolt on it that may be able to tighten down to prevent the floating if that is necessary on any particular system, to prevent tension differences in the two cables from affecting each other (or it's use as a single-cable system). Might require washer(s) on the bolt to allow it to fully clamp this down.

The barrel adjusters are a bit hard to move in the threads; this will be even harder under tension. I'll grease them and see if that's still true--if so, I'll have to see if any of my taps / dies are the right size and thread for these, and chase them to see if that helps.

The angles everything is at seem to be just about perfect for fit on the trike for my usage and handlebar angle, etc., though I won't know for sure till I get it on the bars and try it.

The only two things it doesnt' have that I would like are a mirror mount hole, and a barrel adjuster for the throttle cable.
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Mahe   100 µW

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Re: how to make a proportional regen ebrake lever

Post by Mahe » Jan 31 2021 7:44pm

Nixunen wrote:
Apr 08 2020 6:16am

I made variable regen brake lever using my Hope tech 3 lever and linear hall sensor + magnet. [...]

Voltage goes about 0.10v to 2.5v (2.5v when lever is completely pulled, also there is possible to adjust that, just simple turning that screw more open or more close (tip of screw move either further or closer to sensor and that adjust how long that movement in lever need to be)
That is the most elegant solution I encounter so far! I'd love to reproduce that work but it does not seem straightforward to realize. I'd have a few questions to that end:
- could you provide a seller link or specifications for the hall sensor + magnet you used? I suppose they are various kinds.
- can you explain the role of the screw again please? I understand it is convenient to adjust the distance between hall sensor and magnet and calibrate it accordingly. Do I understand correctly that using an iron screw, the screw itself becomes the magnet sensed by the hall sensor?
- what range of distances between sensor and magnet are we talking about actually? (or between sensor and screw tip, if that's what it comes down to)
- how instrumental is your specific brake model ? Would such an approach work fine with some standard, middle range, say my simple Shimano brake levers? (I'm thinking of the screw, the cavity for the hall sensor a'nd the free range before triggering mechanical brakes). Probably any setup where hall sensor and magnet are brought closer together by braking would do it, right? Like roughly tape/glue the hall sensor on the fixed brake body and magnet on the brake lever, near the point of contact? But sure a clean setup is important. Often there is some play in the brake lever with respect to the fixed part. Could that contaminate the signal to the point of making the sensor useless for braking? (again the distance/sensitivity question)

Many thanks in advance for any hint you may provide!

Mahé

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