Using regenerative breaking as home electric generator

[Galifer]

I've searched a lot online and here but not found any decent info on this. I've seen people rig regular bicycles to car alternators to make a generator. But it would seem efficient to me for space and money, to use one bike for both transport and energy production (for low energy use off grid life or living on the road.

So, my question is:
Can we use a regular ebike with a hub motor that has regenerative breaking, to charge a battery when stationary?
For example, make a stand for it so it doesn't travel, but turn regenerative breaking on to give resistance so you can peddle and generate electricity?

I've seen one video of someone doing similar but having to make complicated re-wiring. I am guessing his motor didn't have regenerative breaking. So I'm thinking it could be simpler with a motor than has regenerative breaking.

Would this be a relatively efficient way of doing things? Relative that is to the more common DIY bicycle generators?

Other questions that arise are, is regenerative breaking a simple 'on/off/ matter, or does regenerative breaking increase as you squeeze the break more? I ask this since I wonder if simply being 'on' might give too much resistance and be too hard to peddle, and if so, having variable breaking would be handy.

Does anyone have experience or links with this? Or other ideas?

I'm thinking that peddling for an hour should be enough to use LED lighting for a very long time! For example there was the Gravity Light, now replaced by NowLight, for which 15 minutes of pulling on the cord with your hands gives 2 hours of light or 15 minutes of phone call use. Using our legs should give far far more. Though I don't know how a hub motor for generation would compare with their system:
https://deciwatt.global/shop/nl01


Would be great to use an electric bike in this way as it would make the bike, the motor, and the batteries, all doubly useful. Whether for low-impact minimal off grid life or travelling on the road. Also aside from not having to duplicate systems, this should be way quieter than the versions using a regular bike with a pulley to an alternator - those things are noisy!

If anyone knows about this, does anyone know what the best hub motor might be for this that's legal in the UK? (We have a 250W limit here which I guess is flexible but yeah that's the official limit).

 

[E-HP]

Based on the principle of conservation of energy, you would burn 700 calories producing 200 watts for an hour. Those calories would come from your legs, sourced by the food you eat. Better eat a lot.

 

[Eastwood]

Yes E-HP is right you will need to eat lots of food lol
Maybe try carb loading the day before :wink:

But no you’re not going to get any charge by trying that. You’d be better off having someone pull you but that can be dangerous if you don’t have a quick break away. You need the weight of the bike and your body weight to help increase the load. Just trying to pedal in place would take you forever to get any charge. I’ve played around with this while riding and nothing gives me a charge unless I’m actually going downhill at speed. I can hold the regen all day and pedal with very very minimum charging.

 

[john61ct]

https://youtu.be/S4O5voOCqAQ

 

[Galifer]

Based on the principle of conservation of energy, you would burn 700 calories producing 200 watts for an hour. Those calories would come from your legs, sourced by the food you eat. Better eat a lot.

That sounds rather pessimistic! Just to give you an example, if you produced 200 watts of electricity for one hour, that would run a regular household LED light bulb for 40 hours continuously! And in a small space, that bulb can be quite sufficient. So let's say you use the light from 5pm to 10pm every day, that's your lighting sorted for 8 days! I'd say that's not bad for the cost of one meal, and better health as a byproduct, wouldn't you?

 

[Galifer]

Yes E-HP is right you will need to eat lots of food lol
Maybe try carb loading the day before :wink:

But no you’re not going to get any charge by trying that. You’d be better off having someone pull you but that can be dangerous if you don’t have a quick break away. You need the weight of the bike and your body weight to help increase the load. Just trying to pedal in place would take you forever to get any charge. I’ve played around with this while riding and nothing gives me a charge unless I’m actually going downhill at speed. I can hold the regen all day and pedal with very very minimum charging.

Interesting. Do you know why that is? Is there some modifications we could make to the system to make it work? Well I guess there are since I've seen someone on youtube from some years back who did so, but I guess I'm asking what would be the simplest way to do it, and the way best suited to still being able to use the bike for transport?

Also the video I saw, I saw no indication that it was a motor with regen capability, I don't know if it was or not, but I figured it might be an easier system to set up if it has regen capability. Do you know of others who have tried or know of any good system? I'd be most interested! Perhaps the regen is just optimised for certain conditions (going downhill with weight) but maybe there is a way to mod it? I actually saw another video of a recumbent bike getting multiple kilowatts from regen braking, so I'm guessing there should be *some* way of getting something out peddling stationary *somehow*...?

 

[Galifer]

https://youtu.be/S4O5voOCqAQ

Funnily enough I saw that before posting. I found it rather silly. First off, its, what was it, 750 watt toaster? I'm talking LED lights, so that's the equivalent of 150 lights! Even to charge a laptop is only what, 50 watts?

Secondly, what's the rush? He toasted it in 1 minute. If he'd relaxed I'm sure the eater could have waited 2 minutes instead of 1!

Thirdly, he used double the total energy needed - one slot was completely empty!

Fourthly, if I wanted toast I would use fire. Though I'd actually be making my own flat bread if I wanted bread, so no worries there, it's piping hot as soon as it's cooked. It's really light production and charging minimal electronic devices that's the issue.

 

[E-HP]

That sounds rather pessimistic!

And that tells a lot about you. Since that's the impression you get from facts, there is no predicted unfavorable outcome in my post, other than what you've concluded from the facts.

 

[calab]

I doubt the calorie measuring devices are accurate at all, you know when you hit the gym for a workout and you step on the tread mill and if you put your hands on the metal part that measures stuff, it suppose to measure how many calories burned but like I said I doubt its accurate at all.

 

[E-HP]

I doubt the calorie measuring devices are accurate at all, you know when you hit the gym for a workout and you step on the tread mill and if you put your hands on the metal part that measures stuff, it suppose to measure how many calories burned but like I said I doubt its accurate at all.

Yes, but fundamentally, you know calories in equals calories out plus losses. If you measure the calories out (charging the battery, or running the lights, etc.), then you know the calories in are at least that number, but more because of losses.

 

[Comrade]

It's really light production and charging minimal electronic devices that's the issue.

A small solar panel and a pocket size power bank would do the trick.

 

[Galifer]

That sounds rather pessimistic!

And that tells a lot about you. Since that's the impression you get from facts, there is no predicted unfavorable outcome in my post, other than what you've concluded from the facts.

No it wasn't my impression from facts. It was my impression from the choice of only sharing that. I didn't mean to be rude, but in the specific context of powering LED lights, and as I pointed out , 200 watts of electricity for one hour being enough to run a regular household LED light bulb for 40 hours continuously hence costing one hour of healthy exercise every 8 days, simply saying to eat a lot did sound quite negative to me. It seems a rather common and dismissive criticism of this form of sustainable energy production. Which was reiterated by the highly exaggerated 750W toaster video. Like if someone had posted about wanting to go on a one hour bike ride in the countryside, how would "Better eat a lot." come across? I think most people do understand that humans cannot do exercise perpetually without eating food.

But if you didn't mean to be negative, no worries!

 

[E-HP]

That sounds rather pessimistic!

And that tells a lot about you. Since that's the impression you get from facts, there is no predicted unfavorable outcome in my post, other than what you've concluded from the facts.

No it wasn't my impression from facts. It was my impression from the choice of only sharing that. I didn't mean to be rude, but in the specific context of powering LED lights, and as I pointed out , 200 watts of electricity for one hour being enough to run a regular household LED light bulb for 40 hours continuously hence costing one hour of healthy exercise every 8 days, simply saying to eat a lot did sound quite negative to me. It seems a rather common and dismissive criticism of this form of sustainable energy production. Which was reiterated by the highly exaggerated 750W toaster video. Like if someone had posted about wanting to go on a one hour bike ride in the countryside, how would "Better eat a lot." come across? I think most people do understand that humans cannot do exercise perpetually without eating food.

But if you didn't mean to be negative, no worries!

both examples are just facts. you could just do math to solve for your own scenario. if there's another source of calories besides food, then that might even a better benefit to share.

 

[DogDipstick]

context of powering LED lights, and as I pointed out , 200 watts of electricity for one hour

.. it is NOT "200 in one hour". You do not need to make " 200"... You need to make MORE.. You will NOT make " 200wH" of electricity, stored, in one hour.

I'll bet you a dollar.

It is closer to 3,4 hours of pedaling to make 200 watt hours.

An average, healthy, human.. can pedal at 100w output. Maybe 140w (I make this in bursts, cannot sustain it, I have datalogged my human output). Typical. 100w output of human energy is you SWEATING, NO FUN AFTER 30 MIN. Like pedaling up the steepest hill you can find. I am very strong, can lift 150 lbs easily, am almost 6 feet tall...and have very much stamina... but pedaling for hours on end is NOT FUN. I would not want to make and store 200wH ever: That is not a trivial amount.

Do you want to sweat for four hours every day? Like you are pedaling up a 20% grade? It is not like.. a nice little ride... A nice little ride, is like 25-40 watts. Perhaps 60 watts, if you are heavy. Pedaling along at 3mph. ON the flat. You would have to pedal at this rate to make 200 wH without breaking a sweat... So 8 hours to make that 200 wH, pedaling along like you are on the flat at 3mph... .

Then the conversion efficiently, then the work efficiency: You lose 10%-30% of your watts hours in the conversion to the battery, ... Lets say 20%. For every 100 watt hours you store, you had to make 120 wH.

You pedal for two and a half hours to make about 200 watt hours stored. IF you are pedaling like you are climbing a very very steep hill. Maybe three.

Every kid int he world knew how long, and how high the " big hill" was, and why they wanted to walk the bike up, not pedal it up. That is when you got off the bike, and began walking, the bike up the hill. We all did this, when we were kids. Imagine pedaling through that for well over two hours.

YOu would be better off, buying a horse, and putting the horse on the treadmill... and feeding him in the field.

Go outside, pedal up the steepest hill you can find, and if you are good with that ( pedaling up this hill for three hours, sweating), go for it, and good luck with your design. I certainly get hungry when I pedal for three hours daily.

 

[Galifer]

It's really light production and charging minimal electronic devices that's the issue.

A small solar panel and a pocket size power bank would do the trick.

Solar panels are handy of course. But I'm specifically thinking about this in the context of a very cloudy country (the UK) in a place that is already extremely shaded by tree cover. So unfortunately relying on solar is too often not an option. So I am more looking for solutions for this specific plan, rather than simply abandoning the idea. So any constructive input on how to make this workable would be greatly appreciated!

Just to give an example of an ebike being used as is, this new bike from Ryvolt can be put on a 'trainer' so it doesn't move as you peddle, to charge the battery through regenerative breaking, which is exactly the kind of thing I'm asking about, you can see this in this video of 'EUROBIKE 2021' at 1 min 34 seconds into the video:

https://youtu.be/36f0r-Hr6_g

I expect their bikes are extremely expensive and they also don't explain in the video how this works. I'm really interested in how we can do this with a DIY build. But at least this shows it's possible *somehow*, via regenerative breaking.

Above I said

I actually saw another video of a recumbent bike getting multiple kilowatts from regen braking, so I'm guessing there should be *some* way of getting something out peddling stationary *somehow*...?

I couldn't locate the video when I wrote that but for those interested here's the video of him getting up to 3.5 kilowatts back into his battery from regenerative breaking downhill:
https://youtu.be/EkuHx55fQlw

 

[DogDipstick]

https://youtu.be/EkuHx55fQlw

Lol the Electrogrom guy. He has been making those claims for years.

Like I said.. I am built like a brick house: Yet I can only do 100w output, continuously... and this means I will be sweating and panting the whole time.

 

[Galifer]

context of powering LED lights, and as I pointed out , 200 watts of electricity for one hour

.. it is NOT "200 in one hour". You do not need to make " 200"... You need to make MORE.. You will NOT make " 200wH" of electricity, stored, in one hour.

I'll bet you a dollar.

It is closer to 3,4 hours of pedaling to make 200 watt hours.

No problem. I was only using those numbers in response to the person who said about eating, since they were the figures that person gave. I still think 3 or 4 hours healthy exercise isn't too bad for 8 days of lighting. That's still maximum half an hour per day.

But besides that, do you really think the maximum energy production we can comfortably get is 50W? This guy seems to get about 150W regular day to day production. I'm not 100% sure if this is the energy that is the actual electrical energy production but it looks like it might be:
https://youtu.be/4X1g8XOu0Hs

YOu would be better off, buying a horse, and putting the horse on the treadmill... and feeding him in the field.

Go outside, pedal up the steepest hill you can find, and if you are good with that ( pedaling up this hill for three hours, sweating), go for it, and good luck with your design. I certainly get hungry when I pedal for three hours daily.

Not sure if I really need to point this out but there are certain costs, space issues, neighbour issues, and ethical issues, involved in using a horse for energy production! Not to mention having to arrange for the horse to be looked after if you go away for as much as a day!

And just to point out, the purpose of my post was not to gather negative critiques of why NOT to produce electricity by peddling. It was rather to collect info on HOW to use an electric bike to generate electricity as simply and efficiently as possible. So I openly welcome positive contributions to this project!

 

[Galifer]

https://youtu.be/EkuHx55fQlw

Lol the Electrogrom guy. He has been making those claims for years.

Like I said.. I am built like a brick house: Yet I can only do 100w output, continuously... and this means I will be sweating and panting the whole time.

You can see him chatting away on his video while producing an average of around 150W quite casually, as shown on the Grin 'cycle analyst'. Are you claiming his video is faked? And to be fair, that dude looks pretty old and not exactly athletic!

Also everyone seems to be ignoring the success of the NowLight which gives lighting powered by HANDS! I actually have one. I don't think it's that hard to realise how much easier it is to produce kinetic energy with our legs than it is with our arms. I really don't get why everyone here seems to be so negative about the idea of electricity production using legs. I would have expected more positivity from a bicycle forum on this topic, to be frank!

 

[DogDipstick]

Yes, I did exaggerate, a little.

Here is a datalog made by the Cycle analyst of me, 170 lb, and my 85 lb bike, pedaling along as hard as I can... At 20mph.. You can see from eh " power trace" at the top, only the section to the right is pure human power + pedal assist:, no throttle... on top of mine. That is me pumping pedals on the flat for as long and as hard as I could. At 20mph.... holding on the flat . Bike is adding 200w.


I made 250w for one eighth of an hour before I tired. ON this section, I averaged 130w, and if I could do this continuously, I would have made 130wH. ( SEE: AVERAGE HUMAN POWER<AVERAGE HUMAN RPM) I briefly peak at 244w output, but only an instant.

 

[HK12K]

Find a stream or river and rig up a paddle wheel on a shaft, pulley on the end, belt to your motor.

Or electrify one of those floating paddlewheel trikes. That could be fun.

I build these things to pedal less, not more. :lol:

 

[stan.distortion]

You would just need a pedal driven DC motor. A cordless drill or automotive heater fan motor would probably be adequate. Add a diode and wire it up to a car battery to "push" power into it. You can get more sophisticated, a car alternator with permanent magnets added would probably give more efficiency and that could make a big difference with the low output and something to show charge level would be good as there's nothing to prevent the battery being damaged through overcharging but a very basic charger pedal charger doesn't have to be complicated. Pretty much any rear hub motor and a 3 phase bridge rectifier would be even better depending on availability.

 

[Comrade]

Solar panels are handy of course. But I'm specifically thinking about this in the context of a very cloudy country (the UK) in a place that is already extremely shaded by tree cover.

Solar panels work on a cloudy day. They would work much better than your idea of generating energy for later use.

If there is shade, just move your solar panel 10-20-30 feet to the side so it's not in the shade?

You seem to be interested in the most difficult and backwards solution to reach the goal. Have you considered getting an aquarium of little tropical fish, and then harvesting the water wave energy? Somebody do the math if the energy required to constantly tap the aquarium to startle the fish to get them to move would offset the wave energy generated. :lol:

 

[Ianhill]

Would you be better off taking a rowing machine and converting that, you can use all your muscle groups and pull like mad, its not continuous like a bike theres a reset period but all we are trying to do is get the maximum amount of work done by the body in an exercise while converting as much as we can into rotation, side product meaning the body will need food and water to output alot of heat as loss on average people need 4× the calorific intake vs the workout.

Nothing wrong with gaining back what u put out but dont expect alot, another possiblity would be a cable multigym that uses a motors for resistance, i know my qs138 70h when fully shorted is hard to turn but i can do it by hand so gearing would be needed to multipky that torque into unmovable by any human then slowly increase a varible resistance to increase the work load no plates needed.

Just chucking some ideas out there for you, in reality like said even a solar panel on a cloudy day will tire the human before the days out and keep going for years with a little wind sidekick and a means of staorage such as a battery its a no brainer and cheaper as theres lots of second hand stuff about to build a system up for a few hundred quid thats 2 stage input plus small amount of storage, like you said 1kwh strored is alot in some situations if its just light your after, im putting something simular in a garden to run a pond and some lighting off grid timed and designed to work in the winter shade so any time of year the pond is trickling away when the pir sensing people in garden and the lights come on at night for a timed period then all off.

 

[donn]

Other questions that arise are, is regenerative breaking a simple 'on/off/ matter, or does regenerative breaking increase as you squeeze the break more?

(Excuse me if this was already answered and I missed it.) I believe regeneration is more a function of the controller, than the motor. There are controllers that support variable regen - e.g., Phaserunner series from Grin Technologies - and more that don't. In the latter case, I expect it's usually possible to configure your choice of regen level, but it will be either on or off, using a switch built into the brake lever. The motor must of course be a direct drive type, or at any rate with no internal freewheel.

 

[DogDipstick]

Other questions that arise are, is regenerative breaking a simple 'on/off/ matter, or does regenerative breaking increase as you squeeze the break more?

Regen can certainly be either or: Depending on controller. They can either be ON/OFF with a set level of regen capability, OR a 0-5v signal that is variable to the set level, like the typical modulation of brakes in a car.

Depends on the controller. Some controllers even just do a REGEN whenever you take the hand off the throttle...

Ie my Kelly controllers can do ON/OFF, 0-5v. or "Throttle release regen".... You choose the type of regen and inputs you have in the software programming. Many people use a 0-5v signal from a " third brake lever" that modulates the current on regen.