Regenerative brakes in the rain

[electr0n]

I was riding into work this morning in the rain and not even very fast maybe around 40 kph and I hit my regenerative brake and felt the tire slide and didn't feel all that safe. I have no rear brakes at the moment beyond regen. I think with winter coming and more slippery conditions I may tune down the regen effect or even turn it off. I can see it being especially dangerous on ice.

Other than that regen is great. Although I do wonder how good it is for batteries to have constant charge reversal.

 

[shorza]

Regen brakes really shouldn't lock up on you. If anything it'll have a very slight lock up effect.
As always, care should be taken when braking on ice or around corners.

 

[biohazardman]

Depending on the system and settings regen can be light to nonexistent or slow you nearly as much as a brake. Sliding on the wet pavement going down a hill or around a corner can happen. Ride a bit different or adjust your settings. If your batts are not up to snuff, won't take the many amps of regen, you will know soon enough with battery or controller damage. Regen killed my controllers multiple times till I figured out my batts would not absorb the amps. So I disconnected it and had no more problems. Better batts that I now have would cure the problem but now have geared motors so no regen there. Good luck and ride safe.

 

[Lessss]

Slippery road can be like ice, the brakeing force was engough to stop the weel spinning.

Please consider a trike for winter riding. Just transfer your kit.

 

[neptronix]

Tune your regen down ( setting EBSLimit to 0 in the infineon software should get it down as low as possible ) and/or get a really wicked fat rear tire

 

[Holz2010]

I was riding into work this morning in the rain and not even very fast maybe around 40 kph and I hit my regenerative brake and felt the tire slide and didn't feel all that safe. I have no rear brakes at the moment beyond regen. I think with winter coming and more slippery conditions I may tune down the regen effect or even turn it off. I can see it being especially dangerous on ice.

Other than that regen is great. Although I do wonder how good it is for batteries to have constant charge reversal.

I have a related question posted here http://endless-sphere.com/forums/viewtopic.php?f=6&t=44405&hilit=5303 as whenever I am going faster than 25 MPH I lay down a patch of rubber when hitting regen. At 40+MPH, it can be a bit of a wild ride, especially if hitting a patch of sand. I have a 20" rear rim with a 5303 hub motor. Even adjusting the regen down to the gentlest setting, this occurs. Methods suggested getting a fatter tire, but I suspect I might still have an issue as I am already running a 2.1x20 tire. (Methods also suggested he might develop a modulated or controllable regen braking set up -- but I don't know if that would happen unless there was a groundswell of interest.) We'll see I guess.

 

[veloman]

you know, I've been thinking about not using regen or not much at all, on all my normal rides which don't require a full battery charge. The charge reversal, and especially the double of typical charge amps that I see during regen can't be great for a battery. Brake wear ..... psh, brake pads don't cost much and still last a while if its dry. I want to be as nice to my battery as possible.

I haven't locked my rear wheel during regen yet, but haven't ridden in real wet conditions yet either.

Maybe I will at least turn the regen down like Neptronix says. Limit it to about 200watts instead of 450w. Now that it's getting colder I'm about to put together a lighter weight Mac build anyway. Something that will use my pedaling effort more efficiently.

 

[Holz2010]

you know, I've been thinking about not using regen or not much at all, on all my normal rides which don't require a full battery charge. The charge reversal, and especially the double of typical charge amps that I see during regen can't be great for a battery. Brake wear ..... psh, brake pads don't cost much and still last a while if its dry. I want to be as nice to my battery as possible.

I haven't locked my rear wheel during regen yet, but haven't ridden in real wet conditions yet either.

Maybe I will at least turn the regen down like Neptronix says. Limit it to about 200watts instead of 450w. Now that it's getting colder I'm about to put together a lighter weight Mac build anyway. Something that will use my pedaling effort more efficiently.

I absolutely have to have regen just as an alternative form of braking. Either that, or carry a drag anchor to throw out! With the long and very steep hills around here, my Avid-BB 7's are literally smoking hot if I use them solely on some downhills.

 

[MadRhino]

Regen can be very powerful when you are using a big motor and high current, yet it doesn't stop the wheel and a tire slip can only be very short unless it happens in a turn on slippery surface. Trust that your rear wheel will regain traction very soon, and get used to a little slip of the rear. Best is to have both good brakes and regen, and to have independent control of them. I find the powerful regen to be a very useful feature on my bikes and it makes them much safer in emergency braking, but I don't brake with regen every time. Most of the time I use the brakes only, for braking precision and also to give a chance to my motor and controller to cool a bit.

 

[Ykick]

+1 MadRhino...

It's really all about the best tool for YOUR job. Everybody has different needs, bike design and terrain. Regen can be a wonderful thing but I don't see the need for it in my daily application.

Not only the issue faced by OP but you need better torque arms and battery capable of surviving significant regn current. If I lived and rode in hilly terrain, I'd deal with all that but as it stands, regen simply doesn't offer any significant benefit to fit my use so I just go with good brakes and let momentum do it's work.

Without steel studs/spikes Ice is flat out dangerous for cars, bikes or trikes. Hell, I've even been in conditions where you can't even walk. Solid ice, stay home. Patchy ice, be careful and learn when to get off the bike and walk through treacherous sections.

 

[steelmesh]

You need a smarter regen system with "traction control" where you compare the front and rear wheel speeds. If the rear delta exceeds a specified frequency, it will need to reduce the regen command to match the front wheel speed, all instantaneously.

I drive beater cars with the ABS not working...safe way to reduce speed in my pickup on that icy bridge is to manually downshift, the rear wheels keep spinning preventing my truck from spinning around in circles. However on two wheels, this is very dangerous. Basic rule for me is, I don't drive on two wheels on slippery roads.

 

[Trackman417]

What kid of controllers are you guys using how many amps are you regening? I regening a MAX of 10 amps and that slows me down a good 1-3mph per second or so. I cant do emergency stops with such weak regen but it helps get some ah's back. On a good 8mile ride I can get back .5 ah's. I don't worry about cooling because I'm trying to use as little power as possible.
I thought regen couldn't lock up the rear wheel.

 

[GCinDC]

ditto, trackman. regen for me is like dragging a wet cat. i wish i could skid!

if i could max more than 15A, i'd get lipo nanos to take advantage, otherwise my 2c charge (20C dishcarge) lipos are enough.

don't slip and slide in winter. put these on and enjoy yourself!

 

[cal3thousand]

I was riding into work this morning in the rain and not even very fast maybe around 40 kph and I hit my regenerative brake and felt the tire slide and didn't feel all that safe. I have no rear brakes at the moment beyond regen. I think with winter coming and more slippery conditions I may tune down the regen effect or even turn it off. I can see it being especially dangerous on ice.

Other than that regen is great. Although I do wonder how good it is for batteries to have constant charge reversal.

I have a related question posted here http://endless-sphere.com/forums/viewtopic.php?f=6&t=44405&hilit=5303 as whenever I am going faster than 25 MPH I lay down a patch of rubber when hitting regen. At 40+MPH, it can be a bit of a wild ride, especially if hitting a patch of sand. I have a 20" rear rim with a 5303 hub motor. Even adjusting the regen down to the gentlest setting, this occurs. Methods suggested getting a fatter tire, but I suspect I might still have an issue as I am already running a 2.1x20 tire. (Methods also suggested he might develop a modulated or controllable regen braking set up -- but I don't know if that would happen unless there was a groundswell of interest.) We'll see I guess.

Doesn't your smaller diameter wheel make it easier to lock up as the ground has less mechanical advantage to continue turning the wheel versus a larger diameter wheel?

 

[Ypedal]

my KMX trike with 5304 in 20" rim at 100v will regen 60 amps at high speed and will cause slight loss of traction on the first hit, the wheel does not lock up but the 3" Vee rubber tire will still squeal from the braking force..

runnin 13.5ah of Nanotech packs, no issues yet.

i would not want this type of braking in winter, and 2 wheels.. suicide. .. but it's perfect on the trike, off-road, i can drift around corners, so much fun.

 

[Cresh]

Hmm, you guys are making me rethink my plans for winter riding in the snow. I was going to use my direct drive mxus when there is snow and ice on the ground and the Mac for other times. My thinking was to use regen braking for going down hills because I thought it was not possible to lock up the rear wheel using only regen - I thought it would act like an ABS, but it sounds like it isn't going to work.

2003 giant Yukon, Mac 7t, 52v

 

[John in CR]

Cresh,
By nature regen can't lock up, but it can slip. For your needs a very light regen force is the way to go. As long as you have a programmable controller, even if the lowest setting is still too strong, then you can mod the shunt in the opposite way used to get higher current limits will reduce the force, and then for forward current just increase the current limits to get take off back where you want.

 

[Ypedal]

for snow and ice, you want very slow and progressive engagement braking, any hard brake force will cause a slide and wipeout.. stick to mechanical brakes for winter imo !

 

[Holz2010]

I was riding into work this morning in the rain and not even very fast maybe around 40 kph and I hit my regenerative brake and felt the tire slide and didn't feel all that safe. I have no rear brakes at the moment beyond regen. I think with winter coming and more slippery conditions I may tune down the regen effect or even turn it off. I can see it being especially dangerous on ice.

Other than that regen is great. Although I do wonder how good it is for batteries to have constant charge reversal.

I have a related question posted here http://endless-sphere.com/forums/viewtopic.php?f=6&t=44405&hilit=5303 as whenever I am going faster than 25 MPH I lay down a patch of rubber when hitting regen. At 40+MPH, it can be a bit of a wild ride, especially if hitting a patch of sand. I have a 20" rear rim with a 5303 hub motor. Even adjusting the regen down to the gentlest setting, this occurs. Methods suggested getting a fatter tire, but I suspect I might still have an issue as I am already running a 2.1x20 tire. (Methods also suggested he might develop a modulated or controllable regen braking set up -- but I don't know if that would happen unless there was a groundswell of interest.) We'll see I guess.

Doesn't your smaller diameter wheel make it easier to lock up as the ground has less mechanical advantage to continue turning the wheel versus a larger diameter wheel?

Exactly! But that's the point -- it is a 20" wheel, so I have to work with that. Currently I use both the Regen and the Discs for braking depending on the situation, but we have some long, steep multi-mile long hills here and that is tough on a disc brake. A larger diameter or larger width tire would definitely help, but I am at the limits now of what the trike design will allow. For those that do use regen, a modulated regen system would be gentler on the torque arms, and in my case, help to eliminate that patch of rubber on the road.

 

[amberwolf]

(Methods also suggested he might develop a modulated or controllable regen braking set up -- but I don't know if that would happen unless there was a groundswell of interest.)

Kingfish is working on this problem now:
http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=42666
though the first tested solution doesnt' work due to the way the controller software works, and he is designing a second method now.

There are controllers (generally not cheap) that do have modulated regen, and I believe Lebowski's also has this.

There are also ways of building your own "controller" that is just for regen, where your brakeswitch would turn off the motor controller and turn on the braking controller, and then you either use the throttle to control braking power (which I don't like) or have an analog sensor in the brake system that determines how much braking to give, and modulates the braking controller accordingly.

You can use the existing power stage in the motor controller to do it, too, by automatically disconnecting the MCU's gate control pins and having your secondary MCU or other control method modulate the gates of the phases so they give the braking you want. You could even tap off of the throttle and brake wires right inside the controller for this. But it would probably be complex to setup and do--less so than building an entire brakign controller, as the power stage is already done for you, but making the control setup is probably just as complex a project.


You can get a primitive two-level braking control by plug braking, wiht a contactor that disconnects the controller's phase outputs form the motor and then shorts two phases for the lower braking level, and shorts all three for full braking.

 

[Holz2010]

(Methods also suggested he might develop a modulated or controllable regen braking set up -- but I don't know if that would happen unless there was a groundswell of interest.)

Kingfish is working on this problem now:
http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=42666
though the first tested solution doesnt' work due to the way the controller software works, and he is designing a second method now.

Hey, thanks for the information Amberwolf. I have no talent for technical solutions like that (and really appreciate what a lot of you guys do here), and if Kingfish, Methods or anyone else comes up with a drop-in solution for modulated ebraking/regen that would be great.
My half-assed solution has been to rapidly stutter the regen button with my thumb to modulate the initial force of braking. Unfortunately, it tends to wear out the regen button faster than one might like, and its none to easy on the thumb either :? Also at 40+mph, thumb control is sometimes a little dicey, so an electronic modulation that can be easier manipulated would be great!

 

[amberwolf]

My half-assed solution has been to rapidly stutter the regen button with my thumb to modulate the initial force of braking.

You're lucky that it works at all for you. On the controllers I have here, they all have such a long delay between engaging the ebrake signal and actually starting any kind of braking, and then another long delay between releasing the signal and ceasing to brake and restarting the motor, that that method will not work on them.

As such, neither will PWMing the ebrake signal, which was a thought I had had before about modulating the braking. If it weren't for the delay, this would be a super-easy way of doing it, by setting the controller for the max amount of regen, and then modulating the ebrake signal's duty cycle, you'd get more or less braking force the harder or softer you pull the lever. Unfortunately I don't know of any controllers that don't have such a long delay, and thus would allow this to work.

I suspect it's because tehy didnt' want spurious noise on the ebrake line to trigger braking, so they used a low-pass filter either in hardware or software, but regardless it makes moot the idea.

 

[cal3thousand]

(Methods also suggested he might develop a modulated or controllable regen braking set up -- but I don't know if that would happen unless there was a groundswell of interest.)

Kingfish is working on this problem now:
http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=42666
though the first tested solution doesnt' work due to the way the controller software works, and he is designing a second method now.

Hey, thanks for the information Amberwolf. I have no talent for technical solutions like that (and really appreciate what a lot of you guys do here), and if Kingfish, Methods or anyone else comes up with a drop-in solution for modulated ebraking/regen that would be great.
My half-assed solution has been to rapidly stutter the regen button with my thumb to modulate the initial force of braking. Unfortunately, it tends to wear out the regen button faster than one might like, and its none to easy on the thumb either :? Also at 40+mph, thumb control is sometimes a little dicey, so an electronic modulation that can be easier manipulated would be great!

That's how I would drive my Ferrari if I had one. No ABS... all foot work

 

[electr0n]

To be clear my wheel didn't lock up but my regen is pretty strong at higher speeds 40kph and up. I'm using lyen's 18fet on the highest setting with an hs3540 at 88.8v nominal. I believe I've seen around 1000 watts during regen peaks, maybe higher, I haven't really made a point to check. The braking force is sudden and very effective at higher speeds.

I'm going to have to get my rear brakes in order this weekend and when the snow hits I'm going to play with the lowest settings on the controller otherwise I will disable it.

 

[shorza]

I fine the lowest setting on my 18 FET Lyen isn't low enough.