Using regenerative breaking as home electric generator

[E-HP]

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.

There's still having to deal with the heat from the motor and controller if regenning for an hour, since it's not an efficient conversion. The best idea pointed out already, if pedaling, would be a high efficiency car alternator, with high copper fill. Those can be up to 75% efficient.

 

[Hummina Shadeeba]

Producing 200 watts while conversing is not hard
https://newatlas.com/the-pedal-a-watt-stationary-bike-power-generator-create-energy-and-get-fit/13433/

Maybe could just put some tape on ur throttle holding it in a braking position.

 

[E-HP]

Producing 200 watts while conversing is not hard
https://newatlas.com/the-pedal-a-watt-stationary-bike-power-generator-create-energy-and-get-fit/13433/

Unless you did this yourself, the only person on this thread that can attest to whether it's easy or hard is DogDipstick. I could try the same with my cycle analyst, but I don't feel like sweating that much, and I know what it feels like just to pedal an unpowered hub motor, even without regen.

 

[Hummina Shadeeba]

I’ve ridden with a wattmeter at 200 watts while talking for hours many times. As the article tells its not that hard especially if you cycle a lot.

Regardless of if u can maintain 200 or 150 watts.. if u want to ride a stationary bike at home and make electricity sounds cool to me


My attempt to quit my job and take up “pro” cycling and just sell my generated electricity back to the power company revealed i wouldn’t make enough energy/money to even support my needed caloric intake


Getting a hub with super low cogging torque would be desirable. Unfortunately I haven’t seen a hub designed for low cogging being made in a long time. I remember some hub in the past that had skewed teeth


https://www.omnicalculator.com/sports/cycling-wattage

 

[E-HP]

I’ve ridden with a wattmeter at 200 watts while talking for hours many times.

This is with a hub motor regenning, correct?

 

[Hummina Shadeeba]

I’ve ridden with a wattmeter at 200 watts while talking for hours many times.

This is with a hub motor regenning, correct?

Nope just regular bike. Of course cogging torque will suck away some of the energy produced unless a non-cogging hub is found. What’s the lowest cogging hub available?

 

[dogman dan]

Anybody else got one of those hand crank flashlights? Works in a pinch, but cranking one long enough to light up for very long is quite hard work! If they could make it easier, they would. Better than nothing in the zombie apocalypse, but its a good thing that is not happening.

Years ago, a guy was working on a prototype sytem like this for use in the third world. He was picking the brains of the guys at E-Bikekit for it, and trying to source just the motors. The idea was that you could charge small batteries, without needing to be daylight. Nowhere near 200 watt hours, but little stuff like cell phones, and small led lights with rechargeable batteries.

It was of course, back when solar panels cost a lot more than they do now, and not a real good idea because of the inefficiency of converting food into electricity. But it can work, just not real efficiently. It could be one way to make a small business out of charging peoples phones in a remote area.

Today, for the same cost of equipment, you can have a 50w solar panel and a small battery, like 200wh, for it to charge. Then you could charge anything small off that battery, day or night. What would you prefer, pedal all day, or watch a panel charge your battery.

 

[E-HP]

I made an attempt yesterday to test regen while pedaling. Note that my max regen is set pretty low, but will still slow the bike down to 6mph on a 10% descent, before it cuts out, and still providing 500W before 6mph (~7A).

I had to find the right gear to get to a speed that would provide decent regen, which was at around 3rd gear. I was able to hit 2A of regen by standing on the pedals and cranking as hard as I could, but that only lasted a several yards, getting up to about 12mph, but I couldn't maintain it. I was able to maintain 10mph, and 1.5A @ 80V for about 2/3 of a block before I decided it was too stupid to go on. People riding by were wondering what the heck I was doing. I figure with losses, half my effort was going toward regen. Getting up to a speed that provides any decent regen by pedaling is nearly impossible.

 

[LewTwo]

Every time I see this thread I can not help but think of those old WW2 movies with one soldier talking on a shortwave radio while the other cranks the generator by hand.

https://en.wikipedia.org/wiki/SCR-284

 

[ColinB]

Yes, a hub motor can act as a generator. I don't know anything about it's efficiency though. Some controllers will work with the throttle and e-brake lever to change the amount of regen. It's a cool idea. Nothing wrong with trying to solve a problem with what is on hand.

If the person already has an e-bike, how will they charge it? I think we can agree that pedaling an un-powered hub motor is not much fun. Would the house run off the ebike battery? Or would a home battery be needed also?

Solar could be better.
- No effort, so the owner can do other things. (Like work. Eat. Sleep.)
- "Home" voltage likely 12 volts. Most ebikes are not set up for 12v, so converters would be needed.

 

[Galifer]

You would just need a pedal driven DC motor.

Are normal direct drive ebike motors AC or DC?

Pretty much any rear hub motor and a 3 phase bridge rectifier would be even better depending on availability.

I would greatly appreciate if you could explain this a bit more. Let's say you have an ebike with a direct drive hub motor that has regenerative breaking, what more do you need and need to do, for good charging of the battery when the bike is lifted up onto a 'trainer'? And how would that differ from simply peddling with the regenerative breaks activated to the degree suitable for comfortable peddling? Thanks!

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.

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

I don't know where you live but here in the UK clouds tend to be larger than 10~30 feet across; and you seem to be deliberately ignoring the fact that I am specifically talking about a place extremely shaded by tree cover. And this is not a post about solar. Even if you want it to be one.

You seem to be interested in the most difficult and backwards solution to reach the goal.

The goal is to learn how to generate electricity using an ebike. If your goal is simply to ridicule the idea, please stop commenting, it is quite unhelpful.

Would you be better off taking a rowing machine and converting that

Thanks for the suggestion but I had really hoped that my post made it quite obvious that the aim is to use an electric bike, and I have made it quite explicit why this is preferred, i.e. making extra use of an item already in use, rather than buying more items and using more space etc. I really have no idea why so many of you on this bike forum are so vehemently opposed to this actually quite common idea and practice of using bikes to generate electricity. You may not like the idea but many people do it. I am just trying to find a less noisy way than the more common route with a car alternator, and being able to use a bike without permanently dismantling it so it can't also be used as a mode of transport!

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.

Ah yes you are right, thanks (and to you too @DogDipstick ). I actually found that out since asking from some further online research, can vary how much regen breaking. I'm still curious if this means we can simply put the bike on a trainer and squeeze the break a bit while peddling or even turning it on a specified amount through the software (anyone here tried that or seen it done?) or whether there is some other modification that might make a significant difference to the efficiency of generating.... Would be great if the solution is that simple, perhaps it is! ....?

 

[Ianhill]

If you touch all the motor wires together and turn the motor thats the max resistance you can get to increase it will need gearing.

Imagine the mosfet sitting inbetween these shorted phases and acting as a gate the more i open the mosfet the closer to the shorted phase postion i get the more resistance in the motor my legs will feel and more power is created from the back emf.

The motor will create some form of ac waveform depending on the magnets shape it could be sinewave or squarewave that then needs to be rectified and smoothed out, if its charging a battery the smoothing part is not so necessary in most cases.

End of day the losses in a system like this is the same reason we don't see the crane and block generator that stacks them high when the grid has surplus and brings the structure to the ground under regen when the supply is low.

Add in humans 25% efficiency in top of that and you will need to be buying alot of diet needs, side quest you will get fitter than you have ever been before like super human athelete fitness levels.

A human can boil a cup of water but the effort involved is mad and the understanding of whats needed in prep is no joke either, after it you will feel like turning jnside out with every muscle hurting and lungs burning no relif for minutes.

Id rather a steady exrecise and buy a panel myself i dont fancy a heart attack needing to use my supply to defibrillate myself.

 

[CONSIDERABLE SHOUTING]

I'm also interested in "converting" home exercise equipment into electrical dynamos, but more because I want a home gym anyway and it seems like a fun project. Might as well get something other than just a better physique out of it anyway, right?

The low tech website had an article just recently about it, and they found an old flywheel-based exercise bike was best; I'll be looking for one too but more due to space constraints at home than anything else, though a rowing machine is also VERY high on that list because I can easily breakdown and stow it.

https://solar.lowtechmagazine.com/2022/03/how-to-build-bike-generator.html

 

[Galifer]

I'm also interested in "converting" home exercise equipment into electrical dynamos, but more because I want a home gym anyway and it seems like a fun project. Might as well get something other than just a better physique out of it anyway, right?

The low tech website had an article just recently about it, and they found an old flywheel-based exercise bike was best; I'll be looking for one too but more due to space constraints at home than anything else, though a rowing machine is also VERY high on that list because I can easily breakdown and stow it.

https://solar.lowtechmagazine.com/2022/03/how-to-build-bike-generator.html

Thanks, the flywheel does sound useful. I don't quite get how their's is a flywheel - perhaps the 'tire' is filled with heavy material? From this post so far, aside from all the negativity, it sounds from the positive contributors that a regular ebike with direct drive motor with variable regen breaking would work as is. But I guess adding a flywheel would greatly improve it. That would be hard to achieve without making a permanent mod, such as maybe filling the tire with sand. Though maybe making lead attachments to go along the inside of the rim between the spokes, maybe secured in place by clipping to the spokes, could work, so long as they don't interfere with the breaking system. Hmm.....

 

[CONSIDERABLE SHOUTING]

I believe its that the rotating mass to generate resistance was a flywheel that would use air resistance.

I think in the article it says why an ebike motor was a bad idea- because you'd have to pedal at high RPMs to generate any real power. They used a friction-mounted wheel on a 24v motor as the "generator" and kept it all DC.

 

[dogman dan]

Too many trees is a definite issue. My RV has 300w of panels on its roof. But where I like to go, it can be putting out only 50w of power at a given time. 100 foot tall pine trees cast shade a long ways. Not always possible to get much out of my solar for the whole day. Once the shade hits in late afternoon, I have to run a generator to keep my house batteries full enough to be able to run my watt hog fan on the heater in the morning. The best I can do is try for camping spots that at least have good sun at noon. But its usually running the generator for an hour in the evening to top up before night up there in the forest.

In short, some places are not great for solar. But nowhere is it good for pedaling up power, if you need more than a few wh to run a light. I could never keep up with my RV by pedaling. Just the motherboards in the propane fridge and other stuff in the RV uses up about 50w day and night. But the panels are still worth having on the roof for sure. When I get a better camp spot, and its not too cold in the AM, I can go a few days without running the generator at all, if its not too cloudy.

 

[stan.distortion]

You would just need a pedal driven DC motor.

Are normal direct drive ebike motors AC or DC?

Pretty much any rear hub motor and a 3 phase bridge rectifier would be even better depending on availability.

I would greatly appreciate if you could explain this a bit more. Let's say you have an ebike with a direct drive hub motor that has regenerative breaking, what more do you need and need to do, for good charging of the battery when the bike is lifted up onto a 'trainer'? And how would that differ from simply peddling with the regenerative breaks activated to the degree suitable for comfortable peddling? Thanks!
...

If you can find an ebike hub motor then ignore the DC part, a hub motor will work as-is but driving a DC motor would take some fabrication work. Look up "3 phase rectifier", plenty of info on how the diodes are arranged and diodes to handle those power levels are cheap. Car alternators have the same kind of rectifier built-in, usually easy enough to remove and most motorcycles have one as a separate unit that also limits charge voltage.

 

[999zip999]

Can you turn a hub motor into a wind turbine if you have a large enough blades

 

[stan.distortion]

Can you turn a hub motor into a wind turbine if you have a large enough blades

Good point, would be a better use of a hub motor, more erratic but greater overall output.

 

[999zip999]

Does Ireland have any windy days ? The pictures I see everyone has to pin their hat down or tie it down with a scarf. Happy saint Patrick's day or only in the USA is that a holiday

 

[stan.distortion]

Does Ireland have any windy days ? The pictures I see everyone has to pin their hat down or tie it down with a scarf. Happy saint Patrick's day or only in the USA is that a holiday

Don't get me started, we have wind a-plenty but inshore it's almost useless without storage, no consistency. It's a no-brainer anywhere there are constant winds though, places like coasts with guaranteed 10mph every dawn and dusk could be a goldmine.

 

[999zip999]

I hope you aren't referring to the Irish people to be high wind it. Breathing is a good exercise and when you're in a pub having a pint or two it's good to let the wind out. If only we you put all that wind to use.
You better wrap up or that Irish wind can cut you.
I told you just don't get me started.

 

[Hillhater]

Can you turn a hub motor into a wind turbine if you have a large enough blades

Good point, would be a better use of a hub motor, more erratic but greater overall output.

The best use for a hub motor is to drive an Ebike as designed.
As others have said , it could be used as a generator, but human power output is pretty pathetic,. An athletic fit cyclist would struggle to generate 100-150 W for a constant output....so impractical really.
Personal (home) wind turbines do work to some extent,...but if they were actually worthwhile do you not think they would be sticking up from every residence at least as common as Solar ?....No,..they are a hobby toy .!
Solar is the only practical mobile electrical energy source.

 

[dogman dan]

A friend of mine lives completely off grid in a very light density area. One thing he really likes is the quiet. He hates his neighbors small wind turbine, not so much because it's all that lound, but because it makes a particularly irritating high pitched noise as gusts of wind hit it. And it often makes this sound all night.

He gets his power from generators, but they don't run while he sleeps, and the noise from them is a low frequency hum, vs a high whine. He needs to get some solar though, and a propane fridge.

 

[stan.distortion]

...
The best use for a hub motor is to drive an Ebike as designed.
As others have said , it could be used as a generator, but human power output is pretty pathetic,. An athletic fit cyclist would struggle to generate 100-150 W for a constant output....so impractical really.
Personal (home) wind turbines do work to some extent,...but if they were actually worthwhile do you not think they would be sticking up from every residence at least as common as Solar ?....No,..they are a hobby toy .!
Solar is the only practical mobile electrical energy source.

Wind is totally viable but only in a few places, I've lived in desserts where you've got a guaranteed wind twice a day, to the sea when the sun comes out and landward when it goes down (iirc, might be the other way around). That's an ideal spot, you could farm it by the acre for both wind and solar and get better yield than crops and I'm assuming those consistent and reliable winds happen in all kinds of regions, not just in sunny places.

Erratic winds could also be viable with masses of storage, hilltops with scope for pumped storage are a good option (especially if there's also scope for some extra hydro) but turbine design also needs to take a step forward, contemporary designs aren't capable of making use of high wind speeds and that's awesome power in 40-60mph gusts, potentially 10kw from a couple of meter span. It just needs flexible masts and fast responding pitch/furling to handle the immense shock loads, carbon fibre is more than capable of doing it and tree trunks do it all the time.