Regenerative Braking.

[Synthman]

Apparently my bike has regenerative braking. I'm slightly familiar with regenerative and dynamic brakes on trains, but to be honest I never noticed anything when I braked on the bike. I thought it would slow the bike down a bit but it doesn't seem to have any braking effort at all.

I have noticed if I take the battery out, and put the key in the bike and switch it on anyway, the lights (front and rear) will come on when the bike picks up speed, although slightly dimmer than usual. The security alarm also still works when the wheel starts going round.

I've also noticed if I coast down long hills my battery indicator creeps back up, and stays up if the descent was long enough. Today I got caught out after 10.5 miles of mostly uphill riding. The battery cut out completely less than a mile from home. However I started pedalling down Headington Hill, and coasted down to the traffic lights and stopped, and I couldn't believe the low warning light went out. When the traffic light turned green I turned the throttle and the bike started moving. I got nearly 250 metres and then the battery cut out again.

So does the regen actually work then? I assume so because I coasted downhill for half a mile and got enough charge for 250 metres. Or do all ebikes do that? Once my battery dies, that's it, it never creeps back up again.

I also get asked quite often if "the bike charges when pedalling" and I say it charges when braking or going downhill.

 

[Ultra Motor]

Apparently my bike has regenerative braking. I'm slightly familiar with regenerative and dynamic brakes on trains, but to be honest I never noticed anything when I braked on the bike. I thought it would slow the bike down a bit but it doesn't seem to have any braking effort at all.

I have noticed if I take the battery out, and put the key in the bike and switch it on anyway, the lights (front and rear) will come on when the bike picks up speed, although slightly dimmer than usual. The security alarm also still works when the wheel starts going round.

I've also noticed if I coast down long hills my battery indicator creeps back up, and stays up if the descent was long enough. Today I got caught out after 10.5 miles of mostly uphill riding. The battery cut out completely less than a mile from home. However I started pedalling down Headington Hill, and coasted down to the traffic lights and stopped, and I couldn't believe the low warning light went out. When the traffic light turned green I turned the throttle and the bike started moving. I got nearly 250 metres and then the battery cut out again.

So does the regen actually work then? I assume so because I coasted downhill for half a mile and got enough charge for 250 metres. Or do all ebikes do that? Once my battery dies, that's it, it never creeps back up again.

I also get asked quite often if "the bike charges when pedalling" and I say it charges when braking or going downhill.

Hi Synthman

I think your analysis is correct. Most motors will 'regen' when going down hill, but barely enough to power the lights. Some newer bikes on the market and systems like Bionix have a specific regen mode that actually uses the engine to brake.

Our new Hybrid 24 has regen and you can feel it, when you squeeze the lever enough to engage the cut out switch but not enough to push the pads to the disc you can feel it.

I think more and more will eventually come with it

Mark

 

[NRG]

Direct drive motors can regen but internal geared types can't due to the internal freewheel. Also, batteries can recover slightly if not used for some minutes so it could be the voltage recovered beyond the cut out voltage.

Normally when regen is in operation the braking effect is very noticeable, on my old Cohnis motor kit it would power the lights and put voltage on the output of the controller but there was no regen taking place, nothing went back into the battery when freewheeling.

 

[Synthman]

I doubt it was my battery recovering because it never has once it cuts out, even after leaving it for a few hours! Is the motor supposed to make sound when regenerating?

 

[banbury frank]

My bike has a Infineon controller it senses when you fit a brake lever switch and starts to Regen is is electronic braking it comes in softly and gradually increases also the cycle annalist tells you how much you have regenerated


all from www.ebikes.ca Homepage of the revolution

Frank

 

[EdBike]

Does regenerative braking really add value to an electric bike. A bicycle is already a very efficient machine, and even going downhill or when braking hard I wonder if there's many joules to make the cost and weight of adding regenerative braking worthwhile?

Cue Physicist?

 

[NRG]

Not in my opinion, there's not nearly enough mass in rider and bike to make it worthwhile, the best use of hills with a bike is to make faster progress down them than fretting over a few Wh put back in to the battery. It works well with hybrid cards as mass and momentum is far greater.

 

[indalo]

I'm no physicist but I'm a little sceptical about the value of regenerative braking on an ebike.

Only recently I was informed by someone more knowledgeable than me that turning a dimmer switch down to lower the lights in a room uses exactly the same amount of electricity as it consumes at the max setting so you can see that I'm a dullard when it comes to electrickery as I didn't know that.

In my naivety, I can't imagine how regenerative braking could be viable on a bike but I'm open to persuation.

Indalo

 

[NRG]

Flecc has posted many times about regen, here's one:

http://www.pedelecs.co.uk/forum/73615-post3.html

 

[mechaniker]

Hi,

regenerativ braking is only possible on direct drive motors, "NRG" is right.

regenerativ brake is a soft or a strong brake depend on how much the controller allow. "ecrazyman" controller is adjustable for regen-brake, can setup by software, Bionx is also adjustable.

It is a nice feature in hill terrain but you need good battery, like sony-konion.
cheap battery cant work with regen-Ampere from 2c
The braking is so good that you dont needso much the normal brakes when using regen and the charging give around 6% more range in hill terrain, in flat is no sense.
This was the good points, now the bad point´s

You need a high-price battery for example "sony-Konion" other battery go brocken if you drive downhill and the charging works with high Ampere.
You need a big size direct-drive with high weight and no freewheel.

I never suggest regen because of to much bad points and trouble on battery, in my eyes is a leight weight motor with freewheel the better option.
On cargo-bike is different, i suggest directdrive with regen and high class battery

regards
frank

 

[Synthman]

If I had access to a treadmill I'd like to empty the battery, put the back wheel on the treadmill, set it to a high speed and leave it for a while to see how much the battery voltage increases.

 

[Mussels]

I'm no physicist but I'm a little sceptical about the value of regenerative braking on an ebike.

Only recently I was informed by someone more knowledgeable than me that turning a dimmer switch down to lower the lights in a room uses exactly the same amount of electricity as it consumes at the max setting so you can see that I'm a dullard when it comes to electrickery as I didn't know that.

In my naivety, I can't imagine how regenerative braking could be viable on a bike but I'm open to persuation.

Indalo

I'm afraid your more knowledgeable friend may not be quite how you think. Years ago this was true when variable resistors were used but now they work differently and do save the world when turned down.

There's an explanation below for those who aren't already bored.
HowStuffWorks "How Dimmer Switches Work"

 

[jimmyhackers]

interesting stuff.

i know that the bad points are up there. regen doesnt really regen a lot

however i think a lot of the people are missing a main point about regen brakes. its essentially another set of calipers making braking quicker,safer and more efficient. also less stress/wear on your real calipers, pads, discs, rims.

i wonder if my controller has regen capability hidden in the instruction manual by chinglish. its labels 3 seperate conectors as brake and only tells me what one of them does. :S so far all braking does is cut the motor.

its brushless and gearless so who knows

 

[jwm]

Yes braking force is increased, but it's only a benefit if bike brakes struggled to stop you.

Regen will undoubtedly become more common, though this will be based on technological advances rather than a real need (along with a sales pitch).

John

 

[flecc]

A hub motor can be specifically designed to be a full electrical brake as well, and three years ago Panasonic released one such e-bike in Japan with 3000 of them as a trial launch, the front hub motor being the only front brake.

I've heard nothing since and they've never come out of Japan.
.

 

[EddiePJ]

I presume that the system wouldn't have allowed for pedalling in a non assist mode?

I have a golf buggy that I use as a wheelbarrow on jobs, and that has an electronic brake. I keep meaning to remove the damn thing as it's a pain in the backside. It over compensates, and acts even harsher as the battery charge reduces. Perhaps those 3,000 bikes suffered from the same issue.

 

[OldBob1]

In the Lift industry they have been using variable frequency drive motors for many years, the speed control is all done electronically. The mechanical brake is only used for stationary parking or an emergency stop.

 

[tsmith2456]

There's a good article about the "energy economics" of regenerative braking here:
http://static1.squarespace.com/static/530f94cde4b0f38aa20cfad0/t/54e28e20e4b05ae6226b267f/1424133664794/regenbraking.pdf

 

[oldtom]

There's a good article about the "energy economics" of regenerative braking here:
http://static1.squarespace.com/static/530f94cde4b0f38aa20cfad0/t/54e28e20e4b05ae6226b267f/1424133664794/regenbraking.pdf

With my limited understanding of the mysteries of electrickery, this appears as a clever piece of work which really debunks all the hype surrounding energy recovery on EAPCs.

Now, I don't know if all the arithmetic and assumptions are accurate or realistic but from personal experience, I have never experienced any noticeable increase to a dwindling battery power level so I prefer to view the system more as a braking assist rather than an energy recovery source.

Tom

 

[jdallan]

Towards the end of a 25 mile ride today on my KTM with Panasonic regen hub motor, after climbing a long gradual incline, I saw the battery indicator bars drop from 3 to 2. I then had a fairly steep downhill stretch using the regen function and saw the bars go back up to 3. After resuming pedalling under power the bars dropped back down to 2 after just under a mile.

Therefore it seems the regen on my bike works but I feel it is more a gimmick than an asset. It can, however, be a useful braking assist as Tom says.

Jim