John Phoenix

I came across this. What do you guys say? I'd like to hear from electrical engineers who really know their stuff for this answer.

" Regenerative Braking? False. There is no such thing. Read below

At best regenerative braking restores 3% (that's 3 miles for every 100) in mild hilly areas and 5-6% in very hilly mountain areas. But the problem is that it will ruin most batteries by forcing too much amperage into them, also weakens the dropouts on the bikes by twisting the axle back and forth. So at this time regen braking is basically a gimmick and in my personal opinion it is not worth it because it can harm a $700 Lifepo4 battery pack and work the dropouts loose.

I thought hard on this, crunched the numbers, asked every vendor, talked to many people with regen systems and we decided against it until a new generation of regen with a soft engage and a better system for returning the amperage to the batteries. "

Edit Er forget debunking, lets just debink this one. LOL.. sorry forum doesn't let you edit the title.

radiorental

All the numbers and calculations aside..

For the average on-the-road scenario, you should be breaking in two cases; lights and emergencies. Neither are likely to be long enough to generate significant energy. If you're breaking a lot, you're doing something wrong and wasting tons of energy.

E.g. on my commute there's a hill where I coast down at speeds of 40mph, why would I burn off that momentum? The only loss is tire friction and wind resistance. If I regenerated then I might have slightly less windresistance but terribly lossy charging. It's a larger net loss.

You travel farther, faster and are therefore more efficient, in my mind, compared to scrubbing speed off in to regeneration which slows you, prolongs the journey and is energy-lossy.

Witt78

I really don't care how much power a regenerative brake puts back into my battery... What makes regenerative brakes soooo worthwhile, is their stopping power.

I'm telling you... If I only had those two little V-Brakes to stop my bike, it would be scary to ride. My Regenerative brakes immediately take the speed off my bike. Period.

I'm soooo glad I have regen brakes.

Witt78

PS - I noticed the "Debinking" thing too; but was going to let it fly. =P

John Phoenix

I see. So the upside is the braking power. Interesting.. the quote I posted above doesn't even touch this issue. I run 36 V now and the V-brakes stop me very well, but im going to 48 soon - motor is rated at 750 watts with no heat loss so I wonder if I will need the extra stopping power ?

I have never seen regen brakes.. my current levers have a motor cut off switch built in. Do regen brakes have this too? Do I need anything special to install regen brakes? If I need them, I will look into getting some.

Witt78

You would be shocked at the braking power I get simply from the regenerative brakes on my Magic Pie 2.0...

If I'm just trying to slow down, I don't use my V-Brakes at all. I simply squeeze a brake lever hard enough to activate the regen brake.

It's only when I'm trying to "Stop" that I use the pads on my physical brakes; and even then, I only use them while under 5 MPH. (Trying to burn off that last bit of momentum.)
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Furthermore, I use SLA batteries, not Lithium. So I don't have to worry as much about regen brakes blasting my batteries with sudden jolts.

Actually, I'm getting a desulfator unit to install with my next check. The desulfator will make good use of those blasts of power from my brakes.
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Regen Brakes are super cool.

prathmann

I agree with the original article that regenerative braking is primarily a gimmick. In normal riding there just aren't that many times that I lose substantial amounts of energy to braking. A few long mountain descents where the road is too winding to let my speed built up and the occasional light that catches me at just the wrong time. But otherwise I tend to use my brakes rather sparingly.

And I certainly don't see a need for a regenerative system for the braking power. Two caliper brakes are more than sufficient for our tandem on mountain descents where we sometimes get up to 60 mph - and that involves much more momentum than an e-bike would have. If you want still more braking power, or a drag brake for extended descents, then it's easy enough to add one - your choice of a disk, drum, or an additional rim brake. But regular brakes can lock up the wheels (not that I apply them that hard), so of what advantage is any additional braking?

Witt78

Disc Brakes are super expensive though... (And they can break.)

My V-Brakes are crap, and if I wanted to replace both of them with disc brakes it would cost me somewhere around $200. Hell, I could go to Walmart and buy a brand new steel frame bike with one disc brake for that much money.

I agree with Prathmann when he says the "Battery charging potential" of regen brakes is a gimmick. But don't underestimate the stopping power that can be provided by that giant magnetic field in your wheel well.

Why NOT use it as a brake?
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I'll tell you what... I'd unhook my front V-Brake. Then challenge any of you guys to a braking contest. I bet I could still win with my stock rear V-Brake and regenerative....

25 MPH to 0...

El Duderino X

I love the disc brake/regen combo on my BionX equipped ride. Considering the extra weight of an ebike setup (up tp 20+ lbs), my own size (6'3" 213lbs) and any added luggage that I may be carrying then the added stopping power of regenerative braking is very worthwhile. It's saved my bacon a few times during high speed urban commutes (especially on rainy days).

The magnetic sensor on the rear brake lever that activates the regen is simple to setup and position. As Witt78 pointed out it can be setup to engage the regen before the brake pads touch the rotor. Love me some regen.

Sangesf

All you need to do is get a controller that has the regen function.

Witt78

I'm using 48 volt SLA, so I have a very heavy battery pack.

Without Regen braking, I'd feel like Indiana Jones; in the mine cart.

It would seriously be scary. lol

miro13car

for those who think it is just gadget, you should try bike with well executed regen.
Stopping power of regen is almost a must on ebike, why to grind metal?
That is what gasoline stuff do - wasting breaking power into friction heat.
I also do not care how much I put back into battery.
Absolutely disagree about damging battery from regen - power electronics take care of this on WELL designed bike.
There are cheap bikes with terrible design regen.
I can't even imagine riding without regen,
try to stop 30KG plus bike only on V breakes even in very light wet road. It would be suiside for me.
You do not need disc breaks on WELL designed regen bike.
So yes you simply forgot about other factors.
MC

Witt78

Even though I have regenerative braking, I would still like to upgrade to disc brakes at some point.

Problem is, buying disk brakes is crazy expensive... I would go out and buy 2, $100 Huffy's with 1 disc brake each. Why go out and buy 2 disc brakes for $200 when you could get two new bikes with it?

Furthermore the all steel frames on those cheap common bikes are just right for an e-bike.
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I might do this just for the dual suspension, and to release my fears of a cracked aluminum frame. The brakes would just be extra.
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BTW, a disc brake on the front tire would be cool. With all the weight on the back tire, there is NO WAY the back of my bike is leaving the ground in a hard braking situation. All your real stopping power on a bike comes from the front tire. (Just don't fly over the handlebars.)

Allen

Because the $200 disk brakes are high quality and the wallyworld disk brakes are the lowest of quality.
For the same money you will have crappy disk brakes and two low quality frames in parted out in your garage.

Witt78

Maybe so, but I don't have the money to drop hundreds into a bike.

Besides, if you're going to start sinking money into an e-bike, why not just get a Yamaha, Cygnus or whatever? I wouldn't mind buying petrol so much, if I was getting 90-115 miles to the gallon. =P

Witt78

So Allan.

(Serious question. I'm not being sarcastic.)

What would you consider a decent quality bike that still has a reasonable "Price VS Performance Ratio"? Somewhere in the $300-$900 range?

A Diamondback perhaps? (I'm on a Sorrento right now, and the aluminum frame kinda makes me nervous to be honest.)

adamtki

I ride a bionx and I love the braking feature of the regen. Without it, my brakes wear out faster and I have to squeeze harder to get the same braking effect. Not only do I save the time and money from changing my brake pads more often, I save the rims on my wheels. If you commute in the rain, you can wear out your rims much faster.

Of course, the energy I get back every time I stop is an added bonus. Any time I need to slow down, I actually start my braking earlier so I can maximize the regen.

I feel safer with regen. The regen braking isn't affected by the rain. And when I'm going down on a long steep hill, instead of blasting down at 40mph, I can enjoy the downhill at 30mph without heating up the brakes.

Allen

I really can't answer that.
It's been 20+ years since I bought a complete bike (with the exception of my ebike).
I found that I always replace nearly everything on a bike with upgrades, so I quit buying complete bikes and started buying framesets. Even on my Ebike the only original parts are the motor, frame, and batteries. Wheels, IGH, handle bars, stem, saddle, etc, are all changed out.
I also have weird tastes in bikes, I prefer things like IGHs over derailers, upright handle bars, dyno hubs, and such.

That said, of the new complete bikes I like (such as the Breezer) they mostly fall in the $800+ range.
They don't have top of the line components, but say 2/3s of the way.
Even outside of biking I've found that cheep tools are usually more trouble than their worth, the most expensive tools are mostly hype, and most things just north of the middle line are are a good happy medium of quality and price.

Witt78

Yeah, I know how that goes...

So what do you think the best motors are? Black Lightning motors are crazy expensive from what I see, and prices on Crystalite are all over the place; depending on where you're shopping. Also, Crystalite has so many different types of motors, I don't know which ones are good and which ones are outdated.
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I just bought my first motor (Goldenmotor Magic Pie II) and I'm having heat issues with the internal controller. (Otherwise, I'm happy.)

Not sure where I'm going to go from here. This magic pie is "Fun", but if I'm using the bike for transportation, I need "Reliable" too. hehe

Allen

I have experience with two very different motors.
My ebike is equipped with a Panasonic mid-drive motor (inline to the chain right behind the bottom bracket).
It's a great motor and has held up as a work horse for thousands of miles--longer than the frame did.

I also have experience with Heinzmann hub motors. I've had no issue with the motor but the charger has given me fits.
Currently the Heinzmann is sitting in my parts bin waiting for me to build a better battery pack (the original was SLA and is at the end of their life) and I'll get a new charger with it. I don't know what I'm going get for a charger yet, not ready to do the build.

I don't have any empirical knowledge with other motors, so any opinion I'd have would just be parroting internet reviews.

dougmc

Actually, these things are important ...

It's not a net loss at all. If you used regenerative braking, then you'd go down the hill slower, and your battery would be more charged at the bottom than it was at the top.

NOTHING is more energy lossy than doing 40 mph. (Except doing 41 mph, or 42 mph, etc.) Seriously, if 100 watts will propel you at 15 mph -- you'll need around 1900 watts to do 40 mph. That energy may come from your awesome legs, your motor or from converting potential energy to kinetic energy as you bomb down that hill.

If you went down the hill at 25 mph and collected the remaining energy to recharge your battery, you'd still get down pretty fast, but would have some help for the next hill you go up (yes, 40 mph worth of momentum will help, but it doesn't last long since you burn it off so fast thanks to air resistance -- energy lost is proportional to speed cubed, but distance covered is only proportional to speed to the first power.) The problem is that the difference between 40 mph and 25 mph is about 1300 watts -- your battery probably can't be charged that fast.

Therefore, the risk of ruining your battery due to charging it too fast is likely real -- hitting the brakes at a high rate of speed probably creates many hundreds of watts of power -- normally this goes into heat on your wheels and brakes, but much of it could be sent into a battery. A good regenerative braking system ought to limit the rate that you can recharge the battery, and if you need more than that it'll either use your brakes for you or make you use your brakes yourself. But if the braking (and therefore recharging) rate is reasonable, then the entire process (recovering energy, using it later) should be at least 60% efficient.

For now, I would imagine that regenerative systems aren't such a big win. To actually take advantage of them, one would have to use the system's brake to slow themselves down as they went down hills and they'd have to go relatively slow to avoid overloading their batteries, and few people want to do that. Ultracapacitators might be the answer to that, but that answer isn't ready yet.

But if somebody had the willpower to use it properly, they certainly could find their range significantly increased by using it, especially somewhere with rolling hills. And it doesn't really require much extra hardware to support it, so it's really quite cheap to add it to an existing speed controller (when designing the ESC, it's not something you can easily add to an existing one.)

El Duderino X

Avid BB7s are excellent mechanical disc brakes. As good as some hydraulic systems. I swear by them and have them on all four of my bikes.
Jensen USA used to sell 2008/2009 Avid BB7s for around $41.00 a pop. Rotor and caliper. They still have good prices on the 2010 models.
https://www.jensonusa.com/store/sub/1...0&pricemax=400

Really, you can't pay too much for a good set of brakes. Safety first!

B.

Witt78

$71 a pop is the price I'm getting. =\ Though that IS the best price I've seen so far.

And you're right. Good brakes are important. Maybe not as important as water, but as important as HOT water!
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Right now I am confident with my braking power. My regenerative breaks slow my bike down in a hurry, and my V-Brakes are more than enough to stop at low speeds when the regenerative break is not that effective. I just hope my battery does not explode or burst into a fireball one day.

That and I'm having heat issues with my Magic Pie II's internal controller... And it's freakin' November. Regenerative brakes probably don't help with heat issues.

miro13car

damage from regen current to battery - it is general statement.
What battery?
Ping for sure,
, my cells can be charged safely at 3C that is 30A , I never saw 30A going into my system from regen on my TidalForce, the most I saw was 20A and it was stopping from 21km/hour downhil.
again what better system you can have which NOT affected by rain and will not block wheel ??
Come on you are roding electric , you are suppose to use regen no griding metal.
MC

chvid

I love my Nine-Continent Hybrid with disk brakes - I average about 15 watt hours per mile, for about a 45 mile range on a Ping 48V 15Ahr battery. The disk brakes work well. Why would I bother with all the extra complexity of regen, ebrakes, two way torque arms, blocking diodes on the Ping battery etc. Plus I like to go fast downhill and save the momentum for going up the other side. I just don't see the point. Modern batteries are so good, that I'd rather just carry another Ping when I want to go 80 miles. And if I switched to Headways, the logic for regen would probably be even less, just because the batteries are so good. That "something you are getting back" is just what you lost in smooth momentum gliding up to a stop sign from far away by eco-driving or in maxing your momentum down a hill. You might as well get the kinetic energy back going up the other side, although as noted you will have higher wind resistance which might be equivalent to the thermodynamic inefficiencies of regen charging...