Regenerative Braking tests
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- čas přidán 29. 11. 2017
- Is regenerative braking really worth it? Well it depends on how often you choose to brake! This might also depend on the application as there is a lot more recoverable energy in other vehicles, but I've tried to convey the basic energy conservation that can be used for all type of electric vehicles. It was difficult to keep this video as short as possible whilst still conveying all the information I've gathered, so I hope you find it interesting!
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Interesting to see regenerative braking used on a bike. For railroads, regenerative braking is much more powerful. In the US it is called "Dynamic Braking." Electric and diesel-electric locomotives use it to control heavy trains (10,000 + tons) while descending long grades. The dynamics can take the entire load of the train to maintain a constant speed without need to use its air brakes or drag its brakes all the way down the hill. Since locomotives do not use regenerative braking to recharge batteries, the power from their traction motors is fed into large, air-cooled, resistor banks where the energy is transformed into heat. Standard dynamic brakes can not completely stop a train. Their effect fades out between 3 or 4 mph and air brakes are used for stopping. Just thought you might like to know.
Steel wheels on rails are a lot more efficient than rubber tyres due to a lower rolling resistance. I've been told a railed vehicle of the equivalent weight over the same distance would consume 1/7th the energy of that a rubber wheeled vehicle.
So a lot of that energy could be captured back in comparison.
You would not believe me, but I'm a locomotive engineer and everywhere in the world electirc trains, electric locomotives and diesel electric locomotives have dynamic braking with resistors lol, even diesel hydraulic locomotives and trains have hydro dinamic braking. But apart from that, newer electric trains and locomotives like siemens vectron are putting their ED braking back to grid and it's recuperative braking ;) More on the same subject, all diesel - electric locomotives are hybrids and they have been around for 100 yrs, but now I guess is just recognised as technology evolves, so it can be used better then just a heavy load transmision that can sustain grater forces :)
@@fauzirahman3285 that explains why it was possible for a strongman to pull 1000 ton train, yet pulling 700-1000 cars even on perfectly flat ground would be impossible. Hysteresis losses in the rubber and also the slight rubbing from expanding and contracting contact patch area (strongly depends on tire pressure) would make the force requirements too much.
In fact because there are so many cases where the brake pads in cars slightly rub against the wheels, it might even be impossible to turn 4000 car wheels at once. Even if each pad rubbed against the wheel and created 250 grams of resistive force at the edge of the wheel, it would still take a tonne of force to simply turn all the wheels!
@Jake\Nerd No. The engineer applies the brakes manually. And newer A.C. motors can stop a train completely.,
Mining haul trucks do the same thing. They will have a diesel generator and electric wheel motors. Most of the time they go down hill they'll use the regen to slow them, and like the trains, dump it across a big resistor bank. Sometimes you can hear a high power fan turn on to help cool the resistors.
Part of the sales pitch for regen brakes is the reduced wear on the friction brakes.
Where Regen really access is at saving your brake shoes. Ebikes tend to wear brake pads down faster because you generally travel at higher speeds and they are heavier. Regen breaking mitigates that problem nicely.
Man! The level of research you've been through is amazing! Thank you!!!
I havn' t heard such a concise explanation of energy transfer since college days. Congratulations Tom, very well done!😎
I must say, This is probably one of the best channels on youtube, I would like to thank you!
Great video and assessment of a lot of the variables involved. My 2 cents: one other major component of loss that was not discussed is the motor itself. I did some measurements with an elevator (straight up, straight down, slow speed, no significant wind drag), using a 1/2HP permanent magnet brushed DC motor. The motor was rated at 90v * 5.4A = 486W. With 745W/HP, that works out to (745 / 2) / 486W = 76.6% motor efficiency. (For ease of math, the motor loss was just over 25%.) That loss applies whether the motor is providing power, or sinking power. In short, I had ~50% loss right out of the motor alone. BLDC (brushless DC motors) can be more efficient than that, potentially past 90%--but still, that's a 20% round-trip loss.
In addition, the bulk of motor loss came out of the voltage, not the current--so I basically provided it 90v, and got 45v back at the same regulated motor speed. This also means that the motor controller has to "boost" the generated motor voltage to just beyond the battery voltage in order to recharge the battery. And unfortunately the easiest way to do it (i.e. no extra parts needed) is by PWMing a short circuit across the motor leads, and dumping the resulting "kick" back into the battery through the blocking diodes on the motor driver FETs. (Basically a boost converter, but with the power source and boost inductor being one and the same device.) While cheap and effective, this design is unfortunately also very inefficient.
At least it's the thought that counts...
An excellent video on the efficiency of regenerative braking
Just found this video, great stuff - I'm thinking of doing the E-bike conversion on my old touring bike and researching the options. I can confirm that overcoming air resistance is the main energy loss on a bicycle I have drop handlebars, on a gentle downhill I can easily coast past somebody on an upright bike who is pedalling furiously, so even reducing the air resistance a bit by going down on the drops makes a huge difference - so presumably would make the use of Regen more effective.
Thanks for the practical test of the system! In addition it would be nice to see how you build the regenerative braking as well :)
As always. Great video and well done tests and explanations :)
On a bicycle I’d assume most of the “wasted energy” is overcoming wind resistance. With a fiberglass shell or even a polycarb windshield I bet that your efficiency would go way up. This was a great we’ll put together video, but I’m waiting for a wiring guide to this setup!!! How does the recharge thumb throttle fit into the wiring? Can you ask the motor to spin up while it’s spinning in reverse while the e-brake is active? Would you get more recharge by slowly easing into the thumb throttle, like in electric motor vehicles? I am so interested in your unique approach to ebike engineering, I hope to have my video up soon detailing some of the work I’ve done on my bike, because, although we have similar performance, our approaches are vastly different!
Thanks for the great videos man. Keep it up
The regen is all done within the speed controller (VESC6), I simply wire in two inputs (input ADC1: twist throttle & input ADC2: thumb throttle), then configure in software that I want the ADC1 to activate throttle and ADC2 to activate regen. When the brake is activated, the throttle from the ADC1 is cut off. In terms of how much intensity of regen braking to use, I'm not entirely sure and will need to do some testing on it. Thanks!!
I would say the used energy for bikes really depends on where/how you are driving and the specifics of your bike.
But in general i would assume that at the speeds most people drive every day it would be the friction of the tires.
The percentage of energy used on a bike, to counter wind resistance is **very** high - on an upright bike, it'll be 80% or so.
For typical bikes the crossover between air restance and rolling resistance is at about 15km/h. Since drag increases with the square of the speed (rolling resistance only linearily), drag is quite quickly the relevant type of resistance. For example going 30km/h instead of 20 (so 50% faster), you need almost 3x (+200%) the power. All "non-refundable" unfortunately.
didn't know about those figures specifically, that whats one of the things I was getting at. Since most of us aren't willing to compromise the design of a upright bike to make it more aerodynamic, I wouldn't worry too much about that % of "wasted energy".
With that being said though, EV's like the Nissan leaf have some pretty undesirable industrial design quirks due to the engineers trying to maximize aero. The battery in the first leaf was only 24 kWh, less energy than found in a single tank of gasoline. (81,891 BTU vs. 115,000 BTU)
it's actually pretty remarkable what we've been able to do with EV's in the last decade alone, especially when considering that gasoline cars have so much more stored potential in almost every circumstance. Yet we still are getting comparable ranges and performance specs because of gains in regen efficiencies and aero.
Finally an intelligent and comprehensive explanation. Thank you.
Great video! You will be a great engineer and are a great teacher.
I spent a lot of time thinking about regen braking in bikes, and the data you generated elucidated the real thing is not that great.
The electronics efficiency could be a reason, but I think battery is the most starving component at the electric system. Maybe with capacitors, as suggested below you could get a few more miles.
Awesome video, thanks. This proves the gut feeling I had surrounding the usefulness of regen B. It also makes sense then that hub motors are losing in popularity to mid-mounted motors, despite the fact that they are not capable of RB. I do think that RB would be a lot more useful in extremely large vehicles, like long haul trucks, mine vehicles and trains. Just think of all those trucks that have to gear down to brake to save their brakes.... There has also been a study of an electric mine dump truck that actually produced more power than it consumed, purely because it was primarily carrying loads down an incline!
Awesome! I was wondering about this myself when riding my friends boosted board, which also has RB. Interesting video Tom :D
Thanks Gavin!
This is the reason why it makes sense to add a freewheel to electric drive. :-) And it was also one of the reasons why my electric motorcycle didn't have regenerative braking.
I really like the simplicity of your project. I am seriously thinking of building another e-bike - mainly because I have almost free access to VESCs (I designed a custom - smaller version). Thank you very much for sharing all your files and so many details of the project!
I was wondering about this too, I wonder how freewheel would compare in efficiency to regen in real use, I suspect that it would do very well in hilly terrain where you can just build speed on the down hill and if you peddle assist. Also, if you run out of range, I wonder how much peddling resistance the electric motor provides that would be eliminated with a free wheel, seems a lot to push that belt and motor along with the bike.
this is just top quality content man you're on fire. keep it up :)
I agree with you Dr Müller
one should also account for different efficiency in other types and makes of battery, generator, and bikes! Might not add up to much difference, but it is a factor. Great video!
Thanks, I think you have vindicated my choice of a non- regenerative e-bike for use in my flat area - the Fens!
Excellent video! I've heard that poor regen efficiency is due largely to internal resistance in batteries. Some have proposed hybrid battery/ultra capacitor set ups. Wonder if you could test a set up like that?
This was very interesting!! Thank you!
thanks, a good factual presentation... don't stop now
THANK YOU! Pretty much the first question everyone asks about my ebike is, "does it have regenerative braking?"
I always responded with, "it's not really worth the added complexity and cost..." But video this will be the perfect explanation!
Cheers!
What complexity? What cost? Any of the BLDC motor controllers available these days will already have regenerative braking enabled, and so there is no additional cost (for the motor or controller), and the only additional complexity is hooking up a switch to enable the feature.
I work as a courier on the evenings and I can burn through breaks very rapidly, so the cost saving in brake pads is a lot more than a few extra battery cells.
An immediate like for this impressive video. Have you considered monitoring the temperature of your battery and charging unit to get an indication as to where some of the power is wasted?
Currently I've only monitored the temperature of the speed controller. But thats a good idea to look into! Thanks
Off track - how do you produce your graphics?
+Richard Wenner I draw it all in Adobe Photoshop, then move things per frame like stop motion animations. Or for the energy meters, I adjust the scale of the coloured bars in Sony vegas video editing software
Slick - its a good result. When we do this I remember an evening I had here in Cardiff with the guy who edited 'Match of the Day' - back in film processing days. The sound on film is physically offset from the image so editing was a fag. He told of nights when the program went out where you could still see the cleaning water on the final broadcast as the film was being fed by hand from final processing directly into the tele-cine. We don't know we are born! :) Thanks
Yeah, your animations are great too :) Have you seen this? Its about MOSFETs temp conditions with better (some, at least) airflow, which you have, - it is sufficient? Cooling of battery (not so tightlyy coupled cells? some active fan too?) may be key to better efficiency, but still its very aggressive discharge/charge, where some pro LiFePo4 are probably better capable also. And BTW, VESC is open-hardware with parts at $50 probably. Its quite curious your 3 VESC4 died as, proper temp handling is core feature of firmware, when limits currents too.
czcams.com/video/UwVQQ_LY5bc/video.html
i added regen to my direct drive rear hub motor kit and one thing that no one is talking about is how good it is at braking without ever locking up. normally when braking as you apply both brakes hard the weight goes forward making the back wheel light and making it lock up, by using regen braking you have a brake that wont lock on the back allowing you to use the front without having to modulate the rear.
great data gathering and analysis. Probably on a recumbent bike the regenerative ratio could be better due to lower wind resistance.
Would a setup like this work: 2 batteries A + B + a generator unit: A is the driving battery, B is the gathering battery. A is driving the bike, B is connected to a generator that takes / converts the kinetic energy like a dynamo into electricity. A smart setup could measure A capacity and reaching a certain point of low voltage switches to B while Generator B is disconnected from B and connected to A. Etc. Not sure whether this could work...
well done Tom. good vids, a quick question- could a front dynamo hub be wired into that vesc 6 thing of yours and put a sort of continual small trickle charge into the battery and would it be worth it?
Great video!!!
Excellent description and analysis. And lovely English countryside. Where is this?
I really like these videos
This gives you a great way to test the effect of aerodynamics. I remember when carrot shaped helmets and closed wheels were a thing in professional cycling. All that does is reduce drag, which you should be able to measure with this setup. I suspect you could improve efficiency quite a bit by reducing energy loss through friction, drag, etc.
Great vedeo. Would like to know energy lost by wind. What was the power at constant speed? Also... the efficiency will change depending on acceleration rate.
Just wondering, in the kinetic energy calculations, you made it seem quite simple. I was just wondering whether you considered the rotational kinetic energy in addition to your translational(linear) kinetic energy. If you were to leave this additional energy out it would make your predictions for the energy regained artificially high. Just wondering.
great info and content Tom. if you dont mind...How well does that gear ratio and electric motor handle the uphills around here (i'm from st albans and also went to herts uni). i was contemplating adapting or buying an electric motor/bike for my hybrid to take me to luton and back each day for my commute but i've seen a few of the electric scooter vids on youtube not really like that sort of gradient and struggle to power the uphills.
Thanks for the vid - the controller supplier discontinued the product, but I imagine there are alternatives around, can I ask which motor/bat combo is yours?
Good test!
Does your bike allow you to pedal also? You can recover some of your own input to the battery. Viscous friction wastes more of the energy the faster you go. As someone has mentioned before, a fully enclosed recumbent (velomobile) would give better results.
regenerative braking is perfect for me where there is lots of up and down hills and i have to constantly hold the brake for several hundred meters to not over speed.
I just ordered a e-bike kit with regen braking so i will se if i love it or not in a month or so
Curious. On a vehicle like this what's better:
- friction free drive train coasting
- regenerative braking
Like traditional drive trains have a ratcheting cassette, but if you could disengage the cassette with a clutch instead of the ratchet it may save on friction, allowing you to coast further than you'd gain from regen.
As it really seems friction and drag is the biggest enemy to your energy reserves here. Being able to coast without expending battery use on flat sections seems key to making the most of this.
i think regenerative braking only will save your brakes over time, i like this vid, it showed me lots of interesting stuff and if its worth getting regenerative braking for a bike if i go electric.If you were to pedal while regen is on would you recharge your battery
Hi Tom. Excellent project and video, but at 4:09 you show a kinetic energy figure of 3.59Wh and you state that theoretically you should be able to recover ALL of this energy if it were not for the inefficiencies of energy conversion. No problem, that is a given, but since you actually recovered 1.27Wh, is the efficiency of the regen braking not closer to 35%?
Available = 3.59Wh
Recovered = 1.27Wh
1.27 as % of 3.59 = (1.27/3.59) x 100 = 35.3% Surely the figures can't lie?
Regards Mark in the UK
+thecorbies Hi Mark, yes that is correct! When riding, I mentioned it was 14% 'efficient', however what I meant to say was "it recharged 14% of the energy used". So later in the video, I adjusted what I meant to say that it gains 15.7% back into the battery. This 15.7% wasn't meant to be the efficiency of the regen period, but instead, how much battery is recharged during the regen period.
Regards
Tom
Good point, but in this case the efficiency of the regen braking is much more than 35%:
Available = 3.59Wh
Recovered = 1.27Wh
Max speed 35mph or 15m/sec, consuption is 30Wh/km
Final speed 0, average consuption is 15Wh/km
Time of breaking 12sec
acceleration is - 1.25 m/ss
Breaking distance 1.25x12x12/2=90m
spent energy for passing breaking distance 0.09x15= 1.35Wh
then 3.59-1.35= 2.24Wh is left for returning back
Recovered 1.27Wh of 2.24Wh or 56% !!! :) .
could the regen braking be more efficient if you added capacitors? and how much more efficeient ?
The most glaring issue with this was the noise. Not that the noise itself is an annoyance but it is clearly the main source of the energy that is lost from the main kinetic->electrical-> kinetic loop. For that matter I would wonder if it were instead possible to place a flywheel next to the rear wheel that can return kinetic energy from braking without producing a lot of noise or drag.
This is interesting but could pedalling help with keeping the battery charged too. I find it interesting in breaking is where we can get some of the energy back!!
Awesomeness. Let me know when you turn into Buddy Pine from the incredibles!
Great video. I think windage loss varies as square of speed.
To prove this can you use your setup measure energy used at various speeds over a fixed distance Viz:
Do a 1 mile trip there and back at 20MPH and measure energy used.
Do a 1 mile trip there and back at 10MPH and measure energy used.
Do a 1 mile trip there and back at 5MPH and measure energy used.
This will give very useful practical results.
It does.
Fd=0.5*Cd*A*rho*V^2
Intresting... I wonder if there could be a way to charge the battery while riding? Maybe a setting that that you could set to like 10% or 5% load can be applied to charge the battery?
The trick is just ride downhill. Thing is that regenerated energy doesn't have the weight penalty of a bigger battery. So, it helps a bit. In some situations, it might be quite a bit.
hope near future Tesla owner - do you think that ‘strategic coasting’ is close to regenerative braking?
(current BMW can disconnect transmission in its ECO mode)
Wondering if Tesla rapid/easy user controlled no-regen can increase distance more than fixed amount of regen
Have you done tests with long hill climbs like 500-1000m of elevation? I’m thinking the efficiency might be higher for those, but curious by how much...
First of all I just want to say that I really like your videos!
I believe that an error is made when comparing the efficiency of the regen braking accelerating and going up a hill. Pounder that you would go up the hill very very slowly, and then go back down very slowly with the regen breaking, then the wasted energy from drag would be minimal. On the other hand, if you would go up the hill a great speed and down again fast because the regen breaking wasn't powerful enough for the slope, then you would waste more energy to drag. Therefor, I think it is wrong to suppose that the 15,7% would be true for the slope example.
Another point is that in theory you would approach your final speed as a limit when time goes to infinity so you would have better efficiency if you accelerated to 25mph instead of 35.
Could you please show the wiring that allows the regen braking? Lots of people like me on the internet trying to figure out how to wire their hub motor kits that have "Low Brake" feature, but no wiring diagram. I agree with other comments that point out the excellent braking quality of regen brakes, especially the anti-lock nature. To optimize... Front wheel hub motor! Add an ultracapacitor... That is my dream bike!
nice video!
Is there a way to put an efficient capacitor in the loop to boost performance? If the maximum recharging rate of the batteries is less than the draw on the system, then that would mean a lot of waste heat. My guess is that if the batteries charge slower than they discharge on this system, a capacitor in between would allow more of the energy to be recovered and either pushed back into the battery slower or used to accelerate the bike on the next leg.
At such low efficiencies using electric regen, you should explore other methods like compressed air, hydraulic, fly wheel, springs etc, basically any method to get something back quick when you have to slow down and waste energy unnecessarily.
Seems to me like if you used better battery management (in software, probably) to control the rate of regen, you could probably significantly boost the efficiency of the recharging by controlling the current rate of recharging. Perhaps an intermediary supercapacitor bank and some MOSFETs?
Tom you are right -15% is the maximum of energy which can be returned by ebike regen during the most agressive riding like yours. With other kind of riding the regen will drop till 2-3% and even till zero.
I checked this on hillclimbing : spent 99Wh and returened 16Wh, i.e. the same 15%. During another long usuall riding including some hillclimbing I gained only 5%.
I deleted my previose post :-) .
THANK YOU! I've long been wondering about this. Neither of my ebikes are capable of reg braking and I've been wondering if I was missing out on anything.
Yes you ate extra ranhe
Riding a bicycle means that most of of the power and also the energy is used to overcome the losses due to the driving resistances, mainly caused by air turbulences. The thrust needed to overcome the driving resistances goes with v², the drive power therefore goes with v³. You cannot expect to regain a lot of energy by regenerative breaking because the kinetic energy is relatively small.
wow that is a fabulous bit of research.I have been telling people that regen is not worth it.Partly because I don't believe the batteries can absorb the regenerated power fast enough.They put out say 15 amps on acceleration but cannot absorb 15 amps on recharge or can they?
Hi Tom could you explain how the regen works please? Eg. If you apply your disc/rim brakes, how is that energy captured? Or is regen only harvested from using the electric motor? And is that the equivalent of 'throwing it into reverse'?
A motor spun backwards can become a generator through some clever engineering. With regen, you brake only with the motor and not with the pads. Feel free to look up a more detailed explanation!
Now I'm even more curious on the le mans hybrid cars like the porsche 919.
If you watch those cars they are able to gather a huge amount of battery charge from their regenerative braking.
This kind of breaking is useful for town taxies (specially in Paris): hybrid cars can use the generator to descelerate not the brakes. Recharging his battery and breaking less w/ physical brakes, these taxies makes 5x more kilometers than others typical taxies!! (By a reducing of brakes replacement and by a better autonomy of his batteries)
I think you should use this braking system in both of the brakes it will increase the efficiency by 30% if u r using on one . Another thing is if u use an another motor in front wheel so while the vehicle will move that motor will also generate energy while moving along with the wheel. I hope i am correct.
Hi Tom, i'm building a similar electrical setup onto a soooter. Are you using a BMS between your battery and VESC? If not, do the cells get out of balance very easily?
Is your regen variable or fixed? On my Chevy Volt, sometimes if i max regen brake, I get a burst of high generation for a very short period, vs if I regen slowly over a longer distance, seems to be better.
Just curious, great experiment!
You should try a super cap as a load for the breaking. Regenerative breaking works if you do it at peak efficiency point. I doubt the batteries are sinking the current the motor could be generating.
Its all about matching impedances. A super cap is really low impedance so the idea is you charge the cap as much as posible and then dump the energy back to the batteries with a boost circuit.
The more current the more breaking.
You could get an idea of what you need by checking the voltaje open circuit at full speed and then the short circuit current at full speed. Do the math and that should give you your equivalent series impedance. Your load should always match that to have the most power transfered.
This is what I am looking for, a super cap to even out up and down hill rides. I don´t want an electric bike I just like to store the energy wasted if I need to break and use it shortly after. A flywheel might do it but I guess it will be to heavy.
I second that motion. But I'dd add a voltage measuring capability accross the capacitor.
When the voltage gets near the capacitors rated voltage (which is often low for super-caps) then the excess current that couldn't be sunk by the now charged capacitor is dissipated as heat over a high wattage resistor.
The same principal easy to understand would be a 220uf 50v capacitor slowly being charged.
Over the cap, you'd connect a 47v zener.
The cap would absorb current until it got to the 47v, and then the other incoming power would be dissipated as heat in the zener - Protecting the capacitor from overvoltage, and allowing the continual un-interrupted load.
@@dancoulson6579
a zener alone would be impractical, but you could get a 30-35v zener and hook it to the gate of a mosfet (or several) with maybe a resistor to take some load off of the mosfet.
also theres no need to let the super cap charge at all, as the more voltaje it has the less difference between the two and so less current being sunk. you should really keep it as low as the boost circuit allows.
The zener thing could work as a sort of protection for the super cap in case it were to "saturate", it should still give you some magnetic breaking though it would be wasting the energy as heat.
if anything the boost converter and the voltage limiter should be capable of handling more power than what you would or could generate typically un average. say a slow breaking or a sudden one where youd be dumping all the kinetic energy from the bike and your body into the regenerative break, to avoid saturating the cap.
also i wouldnt use a normal high voltage cap as they have really high esr compared to super caps. you need energy density not voltage tolerance.
sure 50v makes all easier but it will be huge in comparison and your boost converter would also be bigger becase it would saturate much faster so it would basically have to be as powerful as your motor breaking at which point you might as well do away with the cap and just use the boost converter as a break.
if resistance is constan then the cap at 0v will sink twice as much current as when it reaches 25v (assuming 50v open circuit), and that means half the breaking force, thats why it doesnt matter as much the voltage of the cap as its the impedance.
like how a 100C 1Ah lipo cell can do 100A because its really low impedance even though its only 3.7v.
for city usage which necessitates more stop and go figure it would probably extend range a bit more, especially with pedal assist
You could use a pelletier and a heat sync in the battery to use the heat to produce electricity
That's great. I have a high power kit 52v 40 amps. Can go pretty fast. My city has no bike lanes so it's safer to go faster, when riding alongside the cars. I've been using the regen brake for the main purpose of assisting the brakes when braking from high speed. It's great. I don't even care about the battery regen, just the added brake power is awesome. I wonder why it's not more popular, some people don't even know their controllers are capable of regen braking. It's a great safety feature.
I've been wondering if there is a way to use the brake levers sensor to make a brake tail light for the bike. Any ideas?
Thanks.
I just watched your video and remembered back in my childhood I had a light system that used a generator to power the lights it had a flip switch to drop the head of the unit on the side of the tire. Could this be used to recharge the battery. I was just wondering.
I am trying to recreate a similar setup using a VESC 4. Where did you connect the throttle for braking on the VESC so that it registered as a brake? What application did you use for control?
i have a 48v e bike,rear wheel drive, sometimes i think front wheel drive hub would be more fun, because you could wheelspin everywhere in the mud.
I will have to try your test with my faired recumbent bicycle equipped with a "Copenhagen Wheel" similarly bluetooth enabled. It uses the bluetooth for all control functions, except for pedal input responses, so I have to pedal slowly backwards to enable regen.
One factor I suppose you did consider was to begin your test with a battery less than fully charged so that regeneration voltage differentials could effectively deliver energy to the pack.
I think the Tesla formulation, beside good aerodynamics, is to have a large enough battery and a motor of sufficient power to do regen quite agressively. My Prius does use regen as best it can, but an 8 mile long mountain down hill route I do quite regularly fills the battery to its software governed 80% level in just a few miles, and then it has no place to store the potential/kinetic energy.The big motor/big battery Tesla can probably use much more of that potential energy returning from its climb up.
I was surprised that your E-bike was capable of 35mph. I thought most european e-bikes cut out at 25 kph, and here in the US the legal assist top speed is 20mph(32kph) so I cannot duplicate your top speed test. I do know that my bike is much better aerodynamically than yours.
This is a home made bike, top speed need not apply ;)
He could have gone even faster with a lower gear ratio!
great video...thats exactly what i was thinking will happen and that regen breaking is pretty much a waste of cash and time for its actual use of it...i would rather put the money towards a bigger battery...or some other upgrade.
can you apply the regen break and peddle the bike? and recharge the battery? exchange carbohydrate energy for electrical :)
The vehicle systems are efficient, obviously the mass but also the smart BMS.
Friend of mine drove Uber for 3 years in a Prius and the brake pads weren't even bedded in.
Thanks for the video. I just bought sine wave controllers for one of my bikes and they have EBS braking. Is that the same as regen braking? The other thing is...does the motor have to be compatible with this feature, or do all hub motors allow the controller to take advantage of this option? I'm trying to reduce the wear on my rake pads.
all hub motors are able to do regenerative braking, it is more the matter of controller, if it supports it or not, in combination with a switch (manual or implemented in brake lever) for engaging the RB.
Nice Video
Hi did you make an experiment about what drains most of the battery energy..20" wheels or 26" wheels?..On same distance and same speed?..
Surely the battery can’t be happy with you charging it (braking) at the same rate/current as you’re discharging it (accelerating). Does the VESC not limit the charge rate?
When calculating rb efficiency you should only consider the energy being used to accelerate and decelerate the total mass and disregard wind resistance etc as the energy recovered by the braking is only harvesting from the kinetic energy available(+ potential lost if going down hill or - pe gained if going up hill). Energy lost due to drag etc will be a function of acceleration as this will determine how long it took to reach terminal speed an so will be greater for slower acceleration and this means that all the energy put in cannot be available for braking recovery. Only the kinetic available at the instant of applying the brakes will be available and a great deal will still be lost due to drag and conversion losses during braking. You should find that your actual energy recovery from the available energy is much higher than it first appears.
can you share the details of how you have constructed the system?
The intent of electric assist isn't to be used constantly like on an electric car but to be used for accelerating and a boost up hills. Typically when riding, one would pedal more for cruising and after needing that boost at the red light. The energy input from the cyclist would likely add to the regeneration of battery energy.
It would be interesting to see how much power rolling resistance consumes in general and during regenerative braking. If you check how many watts of power your motor draws at a few velocities, you could determine how much power is required to overcome rolling resistance (or overall resistance due to air drag) and interpolate a curve to get the power dissipated by rolling resistance at any speed. From there you can get a Watt-hour approximation for kinetic energy lost to rolling resistance during regenerative braking. You could also find out what range your system should have at different velocities and what the rolling resistance coefficient is for the road with respect to your bike's tires.
Infinion Air resistance alone, will account for at least 80% of the energy used. Bikes are, ridiculously un-aerodynamic.
I wonder, can you make a like "nos" for ebike with supercapacitors? While accelerating supercapacitors can deliver high current for a short period.
i want to add a flatwound brake that can release the energy again and regen into caps so you get most brake energy back
I dont know why they have not come up with a friction mounted generator.One that is separate from the motor but connected to the battery LIKE THE OLD BIKE LIGHT wheel generator's to charge the battery .It could be powered by the rim front or rear in some fashion and regulated for regeneration and always in the generation mode while in motion unless disabled by a lever or switch.A drive system could be developed based on the rim or hub.It also could be incorporated with regenerative braking.
yea i never expected the region to increase the range much. the big thing is the reduced damage to the breaks
Hello. Do you have a eletrical schematic to do a renegenrative system using a simple standard controller? Thankyou
How much more would it add to also have your pedaling regen the bike and only pedal up a hill or at cruise?
I wonder which is the real efficency of the bike on a test bench. I mean without any drag, air friction and so. The motor has one eficiency, than all the transmission and frictions in the wheels. I guess this is less than 50%, and probably dependant on the cruising speed.
Thanks. I was wondering abozt that for a while. Though it hast obviously other benefits such as less breal wear. (Or in The case of a mpuntainboard: it adds breaka in the first place. Yai :D)
that products no longer available, which is a shame, since i wanted it for a project
Very interesting! We’re adding solar cells to our electric scooter (Model M365) which will be utilized as a range extender. We noticed that the phone app which communicates with our scooter (Mi Home app) shows an energy consumption as low as 50 watts when traveling at a constant speed of approximately 5 to 7 miles per hour. We are presently using the SunPower monocrystalline solar cells, rated at 160 Watts (See Elfeland SP-22 Folding 160 Watt Solar Panels). If these cells can produce half of their rated output we may have a constant input (while the sun is shining) of power - acting as a range extender for the EV scooter. The EV scooter has a 250 watt motor, and a 36 Volt Lithium battery. We purchased a Genasun Boost MPPT Charger which will add power to our battery, from the solar cells. Marissa Muller here on you tube utilized 240 watts of SunPower solar cells to power her 250 watt electric bike across the country, permitting the solar cells to do 60 to 70 percent of the work, while she add the 30% to 40% via peddling the bike. Marissa notes she chose to limit the sunlight’s contribution of power so that she could get some exercise and thus help improve overall health. It’s a story that inspired us and so we too are studying how we can allow nature to help power our electric scooter.
Very nice Ebike by the way! Great video!
if you added a cap bank you would recover more of the energy from braking.
What are things you could do to increase the regen braking's efficiency? It seems most of your efficiency loss is through there, rather than in acceleration.
What are you using to apply or engage this regeneration brake and how does it work