18 ms·

How to build a bike generator with control panel

112 points by jfoucher 5y ago

thehappypm 5y ago
One kiloWatt-hour of electricity costs around $.24 in my state. If you can output 100 Watts for 1 hour, that’s .1 kWH. Do it every day for a year that’s ~36 kWH, or about $10 in electricity.
barbazoo 5y ago
> This website runs on a solar powered server located in Barcelona, and will go off-line during longer periods of bad weather. What a neat idea
- mywacaday 5y ago
  I was wondering what the 84% floating batteryicon was about until I scrolled back up
aliswe 5y ago
I wonder what the HN pundits say about the efficiency? (no sarcasm intended)
- WJW 5y ago
  It's not very high, obviously: energy is conserved and humans are not particularly efficient in converting food into energy. It's also not very effective: the article itself mentions that boiling the water for a single cup of tea took almost an hour at 60 Watts. Imagine how long you'd need to pedal to power a microwave with this, or a clothes dryer. Each of those would need at least 10x more power, so you'd be looking at 10 hours of pedaling for a single load of laundry. At that rate it's quicker to just do away with electricity entirely and wash your clothes by hand. It could be useful in an emergency situation where you have more food than electricity though, or if you really really need something small that can only work on electricity like a HAM radio.
  - aliswe 5y ago
    I'm more into the lines of "how would this be improved with least amount of effort and most value"?
    - WJW 5y ago
      Honestly as long as it remains human-powered I don't see a lot of value to be gained. Humans just don't generate a lot of raw power. The quickest way to improve this system would probably be to attach it to a set of wind turbine blades or a waterwheel, but "how to build a very poor wind turbine" is not nearly as catchy as a blog post title.
  - toast0 5y ago
    For a washing machine especially, the inefficiencies of turning mechanical energy to electrical energy and then back are going to be be pretty bad. If you could work out gearing to spin the tub mechanically, it might be better, although the back and forth motion of agitation isn't something I'd know how to do. Pumping the water and spin dry should be relatively simple, although getting enough speed for effective spinning may be a challenge.
    - pitaj 5y ago
      > although the back and forth motion of agitation isn't something I'd know how to do A smaller wheel linked to a larger wheel, where the smaller wheel is driven by the bike. As the smaller wheel spins, the linkage will move back and forth. If the second wheel is sufficiently larger, it won't be rotated enough on the push stroke for the pull stroke to complete a rotation, and will oscillate instead. https://imgur.com/B1ykmpB https://imgur.com/B1ykmpB
    - masklinn 5y ago
      Mechanical washing machines were a thing before ww2. You might be better off finding one in an old barn and replacing whatever it uses (likely a crank) with a PTO you can link to a bike. Adapting a modern washing machine would likely be quite a bit more difficult.
- jeffalyanak 5y ago
  I think they made the right choice in designing it around providing an adjustable mechanical resistance. As it's primary goal is for working out and charging cell phones I think it's best compared to a normal workout bike, which outputs all of the energy as heat (and sound). Sure, the usable energy is minimal, but it's higher than zero and it can meaningfully top up your smaller electronics devices.
olau 5y ago
I was curious whether they talked about the practicality of the whole setup, and they do, e.g. > Electric kettles that run on grid power are often very powerful and boil water in a matter of minutes or even seconds. Boiling water using a bicycle generator will take a lot more time, but it’s perfectly possible. We acquired a commercial 12V electric kettle with a vacuum insulated reservoir of one litre. During a test, boiling water for one cup of tea took slightly more than one hour at an average power production of 60W. To be honest, although I realize it would be ridiculous, but if inverters were small and cheap, I would personally prefer having an exercise bike plugged into the grid. That way my exercise energy would at least be useful to someone, somewhere.
- TheSpiceIsLife 5y ago
  Inverters are tiny and cost almost nothing. Here's one for under $50 that will do what you want: https://www.ebay.com.au/itm/Car-Power-Inverter-12V-to-240V-AC-Converter-200W-With-4USB-Phone-Charger-AU-/193941414985 https://www.ebay.com.au/itm/Car-Power-Inverter-12V-to-240V-A...
  - rootusrootus 5y ago
    A grid-tie inverter will be quite a lot more expensive.
  - explorigin 5y ago
    200W isn't a lot of power. Most microwaves are 1KW. You'll need an inverter that can do that at least to run a fridge constantly and a microwave periodically.
    - _carbyau_ 5y ago
      Inverter is not a battery so it is translating the useful work from the human directly. I am imagining a 1kW sprint run by Uni students for microwaved ramen noodles!
    - TheSpiceIsLife 5y ago
      I swear the comment I replied to said: "would personally prefer having an exercise bike plugged into the TV..." When I replied to it. However, I have no proof and am often wrong.
horsawlarway 5y ago
Alright - this is mostly off topic, but I see this website pop up here fairly frequently, and I really really hate the battery level indicator. I find it makes reading the actual content far more difficult than it should be. I get that it's intentionally drawing attention to the fact that this site is solar powered, but it pulls my eye to the line literally every time I scroll. I end up closing the tab out without finishing the article - it bothers me so much. Personally - I'd really love to have an option to hide it. I'm completely down for showing it by default - but after a minute or two on the site, the novelty has worn off and I'd really rather focus on reading your content.
- marcodiego 5y ago
  For this and other cases, I use this extension: https://alisdair.mcdiarmid.org/kill-sticky-headers/ https://alisdair.mcdiarmid.org/kill-sticky-headers/
- savingGrace 5y ago
  I had no clue what you were referencing. I'm using Brave, and I have it automatically turn on the 'Speedreader' mode. When I disabled it, I then saw what you are referencing. I know the other browsers also have a mode that gets rid of all the junk and lets you just read the articles. Maybe you should give that a try?
  - MBCook 5y ago
    That’s what I had to do, use Safari’s reader mode. I too found the charge level indicator too distracting to be able to read the article as-is.
- seanb 5y ago
  Drop the `solar` subdomain: https://www.lowtechmagazine.com/2022/03/how-to-build-bike-generator.html https://www.lowtechmagazine.com/2022/03/how-to-build-bike-ge...
  - horsawlarway 5y ago
hbarka 5y ago
I know this is way off-topic but in Calum’s YouTube video about British Intelligence in Gibraltar he mentions a pedal-powered generator which was the primary source of power for the agents working deep inside the bunker. https://youtu.be/2n97nh9PKH4 https://youtu.be/2n97nh9PKH4
TobySKT 5y ago
mixedmath 5y ago
I'm impressed at the relatively high efficiency of the system. Pedalling at 150 watts and recovering 100 watts of electricity is higher than I would have expected from such a simple system. I'm very curious how much better the system would perform if the flywheel were attached directly to the drive-train instead of via friction roller. In practice this might not give much higher efficiency, but I would guess that the chain and primary sprocket would wear out slower than a tire friction-running a flywheel. (They mention that they don't do this because this because it would be harder to build. I believe that. But I'm still curious.)
- gruez 5y ago
  > I'm impressed at the relatively high efficiency of the system. Pedalling at 150 watts and recovering 100 watts of electricity is higher than I would have expected from such a simple system. It doesn't seem very surprising that motion can be converted to electricity at 66% efficiency. Normal power plants[1] can convert heat to electricity at 64% efficiency. It'll be much more interesting to see the end to end efficiency of this, ie. how many calories were consumed compared to electricity were generated. [1] https://en.wikipedia.org/wiki/Combined_cycle_power_plant https://en.wikipedia.org/wiki/Combined_cycle_power_plant
  - KennyBlanken 5y ago
    A well-trained athlete can achieve about 33% efficiency in terms of calories used (not 'consumed' - we're talking about energy coming from glycogen and fat, in addition to whatever is eaten. The human digestive system can only process a couple hundred calories per hour before it starts diverting blood flow to the digestive system, which impairs athletic performance significantly.)
- samatman 5y ago
  I've done enough bike wrenching to have raised an eyebrow on that. What you need is two gears on the flywheel, rather than one, a gear rather than a friction wheel on the generator, and some way of tensioning the second chain which you run between them. This isn't the kind of harder to build that should stand in the way, although I will grant that the single gear was already on the wheel and changing that does involve, well, changing that. This gets ~10% efficiency back, which for a generator is huge. It's probably the only efficiency gain left, other than a gear cassette to optimize power to a target voltage.
gwbas1c 5y ago
FWIW: https://www.lowtechmagazine.com/2022/03/how-to-build-bike-generator.html https://www.lowtechmagazine.com/2022/03/how-to-build-bike-ge... is much easier to read. The current link is the version of the site where the server runs off of solar power.
- codazoda 5y ago
  I like the solar version better. :shrug:
rootusrootus 5y ago
150W is a pretty good workout sustained for an hour. Humans can do what, maybe 1000W or so at peak? Non-athletes, I mean. But nobody is putting out 1000W for very long. I'd have guessed that over an hour 75W-100W is more realistic. I recall playing around with a bike generator at the local power plant about 30 years ago and it was hard to keep a regular light bulb lit for any length of time.
- thehappypm 5y ago
  It would be a lot easier today, LED bulbs are about 10x more efficient! Someone outputting 100W could light up an apartment.
- masklinn 5y ago
  > Humans can do what, maybe 1000W or so at peak? Non-athletes, I mean. 1000W is “trained biker sprinting”. > I'd have guessed that over an hour 75W-100W is more realistic. The mechanical output which can be maintained over a work day is generally estimated around 75W. So accounting for losses 100We for an hours is realistic but vigorous effort.
- matsemann 5y ago
  I like to bike, but am just an amateur. My ftp is ~280W, which is what I can sustain for a long time without accruing too much lactic acid. I've held 200+W for hours. Just to give a baseline. A heavier person could probably do even more. A track cyclist can reach 2000+W bursts, but they are freaks.
Ottolay 5y ago
This is so cool. Viable for LED lighting in an off-grid situation when there is little sunshine for solar panels.
kitd 5y ago
A rowing machine employs a wider range of muscles and so will enable more power to be produced. Here's a DIY rowing generator that one guy built: https://www.lybrary.com/a-rowing-machine-which-generates-electricity-a-36.html https://www.lybrary.com/a-rowing-machine-which-generates-ele... He claims 100W steady output but I'm sure more is possible. One advantage of the bike over a rower is you can be doing other things at the same time, like reading a book, or tapping on a phone or keyboard. On a rower ,only passive activities like listening to music or watching a screen are realistically possible.
- KennyBlanken 5y ago
  Leg muscles are the largest and most powerful in the human body and it's pretty easy for them to exhaust the body's aerobic capacity. The number of muscles involved is not a limitation for longer duration power generation. There's aerobic capacity, but also glycogen and oxidative (fat) energy pathway efficiency. Experienced endurance athletes usually have quite high oxidative energy capacity/efficiency. These sorts of projects are silly because even a decent average adult male will struggle to make 100-150W for an hour.
  - kitd 5y ago
    Leg muscles are the most powerful in he body, but they are not used to the extent on a bike as they are on a rowing machine. Additionally, they extend the work done by the arms and back, ie the work is not just the sum of the individual muscle movements, but the combined action. Yes, it is silly and the author intimates that in the OP and the article I linked too, but I don't think meaningful power generation is the point of the exercise. BTW a decent average male should be able to do 100W easily for an hour. I'm a (not particularly powerful) rower in my 50s and can easily sustain 150W for an hour, ie circa 120W accounting for generator inefficiencies.
  - mcronce 5y ago
    You're absolutely right that projects like these are silly as anything more than a fun tinkering exercise, but that 100-150W number is a low estimate. I'm fairly small and out of shape and can produce 180W for an hour. In-shape amateurs can do better than that. Still not enough to be even remotely practical as a generation method, but substantially more than 100-150W
gwbas1c 5y ago
It's be interesting to have this wired to an electric car charger.
- ygra 5y ago
  I guess the more sensible option would just be to use a bicycle to get around. Simply because with the car you require most power just to get the car moving, not so much the person inside.
- dahfizz 5y ago
  At 100 Watts output, it would take 800 hours of biking to fill a tesla battery pack.
fuzzy2 5y ago
Reminds me of the toaster challenge video[1] where Robert Förstemann, German track cyclist, powers a 700 Watt toaster for over a minute on an exercise bike. Absolutely insane. [1]: https://www.youtube.com/watch?v=S4O5voOCqAQ https://www.youtube.com/watch?v=S4O5voOCqAQ
- jdechko 5y ago
  That was my first thought as well.
calvinmorrison 5y ago
One thing I think that could be changed here is a different storage medium. For example, flywheel storage instead of batteries, or compressed air storage, instead of batteries. Since batteries can't be charged faster than a certain rate, it creates a limitation. Of course, compressed air is only so useful and not so efficient to turn into electricity but, still an idea.
throwaway81523 5y ago
The main reason I want a bike generator is to power my laptop, so that if I'm going to be sucked into web browsing regardless, I'll at least have to get some exercise in the process.
amelius 5y ago
Efficiency?
jakedata 5y ago
If I were to create such a system today I would take advantage of an inexpensive (~$10-$20) MPPT (maximum power point tracking) solar controller to regulate the unruly DC output of the generator or rectified alternator. It will sweep the input voltage/amperage to find the maximum power production for a given power source. These devices will automatically charge either a 12v or 24v battery and also provide several 2a USB ports for device charging.

112 points by jfoucher 5y ago

One kiloWatt-hour of electricity costs around $.24 in my state. If you can output 100 Watts for 1 hour, that’s .1 kWH. Do it every day for a year that’s ~36 kWH, or about $10 in electricity.

barbazoo 5y ago

> This website runs on a solar powered server located in Barcelona, and will go off-line during longer periods of bad weather. What a neat idea

mywacaday 5y ago
I was wondering what the 84% floating batteryicon was about until I scrolled back up

aliswe 5y ago

I wonder what the HN pundits say about the efficiency? (no sarcasm intended)

WJW 5y ago
It's not very high, obviously: energy is conserved and humans are not particularly efficient in converting food into energy. It's also not very effective: the article itself mentions that boiling the water for a single cup of tea took almost an hour at 60 Watts. Imagine how long you'd need to pedal to power a microwave with this, or a clothes dryer. Each of those would need at least 10x more power, so you'd be looking at 10 hours of pedaling for a single load of laundry. At that rate it's quicker to just do away with electricity entirely and wash your clothes by hand. It could be useful in an emergency situation where you have more food than electricity though, or if you really really need something small that can only work on electricity like a HAM radio.
- aliswe 5y ago
  I'm more into the lines of "how would this be improved with least amount of effort and most value"?
  - WJW 5y ago
    Honestly as long as it remains human-powered I don't see a lot of value to be gained. Humans just don't generate a lot of raw power. The quickest way to improve this system would probably be to attach it to a set of wind turbine blades or a waterwheel, but "how to build a very poor wind turbine" is not nearly as catchy as a blog post title.
- toast0 5y ago
  For a washing machine especially, the inefficiencies of turning mechanical energy to electrical energy and then back are going to be be pretty bad. If you could work out gearing to spin the tub mechanically, it might be better, although the back and forth motion of agitation isn't something I'd know how to do. Pumping the water and spin dry should be relatively simple, although getting enough speed for effective spinning may be a challenge.
  - pitaj 5y ago
    > although the back and forth motion of agitation isn't something I'd know how to do A smaller wheel linked to a larger wheel, where the smaller wheel is driven by the bike. As the smaller wheel spins, the linkage will move back and forth. If the second wheel is sufficiently larger, it won't be rotated enough on the push stroke for the pull stroke to complete a rotation, and will oscillate instead. https://imgur.com/B1ykmpB https://imgur.com/B1ykmpB
  - masklinn 5y ago
    Mechanical washing machines were a thing before ww2. You might be better off finding one in an old barn and replacing whatever it uses (likely a crank) with a PTO you can link to a bike. Adapting a modern washing machine would likely be quite a bit more difficult.
jeffalyanak 5y ago
I think they made the right choice in designing it around providing an adjustable mechanical resistance. As it's primary goal is for working out and charging cell phones I think it's best compared to a normal workout bike, which outputs all of the energy as heat (and sound). Sure, the usable energy is minimal, but it's higher than zero and it can meaningfully top up your smaller electronics devices.

olau 5y ago

I was curious whether they talked about the practicality of the whole setup, and they do, e.g. > Electric kettles that run on grid power are often very powerful and boil water in a matter of minutes or even seconds. Boiling water using a bicycle generator will take a lot more time, but it’s perfectly possible. We acquired a commercial 12V electric kettle with a vacuum insulated reservoir of one litre. During a test, boiling water for one cup of tea took slightly more than one hour at an average power production of 60W. To be honest, although I realize it would be ridiculous, but if inverters were small and cheap, I would personally prefer having an exercise bike plugged into the grid. That way my exercise energy would at least be useful to someone, somewhere.

TheSpiceIsLife 5y ago
Inverters are tiny and cost almost nothing. Here's one for under $50 that will do what you want: https://www.ebay.com.au/itm/Car-Power-Inverter-12V-to-240V-AC-Converter-200W-With-4USB-Phone-Charger-AU-/193941414985 https://www.ebay.com.au/itm/Car-Power-Inverter-12V-to-240V-A...
- rootusrootus 5y ago
  A grid-tie inverter will be quite a lot more expensive.
- explorigin 5y ago
  200W isn't a lot of power. Most microwaves are 1KW. You'll need an inverter that can do that at least to run a fridge constantly and a microwave periodically.
  - _carbyau_ 5y ago
    Inverter is not a battery so it is translating the useful work from the human directly. I am imagining a 1kW sprint run by Uni students for microwaved ramen noodles!
  - TheSpiceIsLife 5y ago
    I swear the comment I replied to said: "would personally prefer having an exercise bike plugged into the TV..." When I replied to it. However, I have no proof and am often wrong.

horsawlarway 5y ago

Alright - this is mostly off topic, but I see this website pop up here fairly frequently, and I really really hate the battery level indicator. I find it makes reading the actual content far more difficult than it should be. I get that it's intentionally drawing attention to the fact that this site is solar powered, but it pulls my eye to the line literally every time I scroll. I end up closing the tab out without finishing the article - it bothers me so much. Personally - I'd really love to have an option to hide it. I'm completely down for showing it by default - but after a minute or two on the site, the novelty has worn off and I'd really rather focus on reading your content.

marcodiego 5y ago
For this and other cases, I use this extension: https://alisdair.mcdiarmid.org/kill-sticky-headers/ https://alisdair.mcdiarmid.org/kill-sticky-headers/
savingGrace 5y ago
I had no clue what you were referencing. I'm using Brave, and I have it automatically turn on the 'Speedreader' mode. When I disabled it, I then saw what you are referencing. I know the other browsers also have a mode that gets rid of all the junk and lets you just read the articles. Maybe you should give that a try?
- MBCook 5y ago
  That’s what I had to do, use Safari’s reader mode. I too found the charge level indicator too distracting to be able to read the article as-is.
seanb 5y ago
Drop the `solar` subdomain: https://www.lowtechmagazine.com/2022/03/how-to-build-bike-generator.html https://www.lowtechmagazine.com/2022/03/how-to-build-bike-ge...
- horsawlarway 5y ago

hbarka 5y ago

I know this is way off-topic but in Calum’s YouTube video about British Intelligence in Gibraltar he mentions a pedal-powered generator which was the primary source of power for the agents working deep inside the bunker. https://youtu.be/2n97nh9PKH4 https://youtu.be/2n97nh9PKH4

TobySKT 5y ago

mixedmath 5y ago

I'm impressed at the relatively high efficiency of the system. Pedalling at 150 watts and recovering 100 watts of electricity is higher than I would have expected from such a simple system. I'm very curious how much better the system would perform if the flywheel were attached directly to the drive-train instead of via friction roller. In practice this might not give much higher efficiency, but I would guess that the chain and primary sprocket would wear out slower than a tire friction-running a flywheel. (They mention that they don't do this because this because it would be harder to build. I believe that. But I'm still curious.)

gruez 5y ago
> I'm impressed at the relatively high efficiency of the system. Pedalling at 150 watts and recovering 100 watts of electricity is higher than I would have expected from such a simple system. It doesn't seem very surprising that motion can be converted to electricity at 66% efficiency. Normal power plants[1] can convert heat to electricity at 64% efficiency. It'll be much more interesting to see the end to end efficiency of this, ie. how many calories were consumed compared to electricity were generated. [1] https://en.wikipedia.org/wiki/Combined_cycle_power_plant https://en.wikipedia.org/wiki/Combined_cycle_power_plant
- KennyBlanken 5y ago
  A well-trained athlete can achieve about 33% efficiency in terms of calories used (not 'consumed' - we're talking about energy coming from glycogen and fat, in addition to whatever is eaten. The human digestive system can only process a couple hundred calories per hour before it starts diverting blood flow to the digestive system, which impairs athletic performance significantly.)
samatman 5y ago
I've done enough bike wrenching to have raised an eyebrow on that. What you need is two gears on the flywheel, rather than one, a gear rather than a friction wheel on the generator, and some way of tensioning the second chain which you run between them. This isn't the kind of harder to build that should stand in the way, although I will grant that the single gear was already on the wheel and changing that does involve, well, changing that. This gets ~10% efficiency back, which for a generator is huge. It's probably the only efficiency gain left, other than a gear cassette to optimize power to a target voltage.

gwbas1c 5y ago

FWIW: https://www.lowtechmagazine.com/2022/03/how-to-build-bike-generator.html https://www.lowtechmagazine.com/2022/03/how-to-build-bike-ge... is much easier to read. The current link is the version of the site where the server runs off of solar power.

codazoda 5y ago
I like the solar version better. :shrug:

rootusrootus 5y ago

150W is a pretty good workout sustained for an hour. Humans can do what, maybe 1000W or so at peak? Non-athletes, I mean. But nobody is putting out 1000W for very long. I'd have guessed that over an hour 75W-100W is more realistic. I recall playing around with a bike generator at the local power plant about 30 years ago and it was hard to keep a regular light bulb lit for any length of time.

thehappypm 5y ago
It would be a lot easier today, LED bulbs are about 10x more efficient! Someone outputting 100W could light up an apartment.
masklinn 5y ago
> Humans can do what, maybe 1000W or so at peak? Non-athletes, I mean. 1000W is “trained biker sprinting”. > I'd have guessed that over an hour 75W-100W is more realistic. The mechanical output which can be maintained over a work day is generally estimated around 75W. So accounting for losses 100We for an hours is realistic but vigorous effort.
matsemann 5y ago
I like to bike, but am just an amateur. My ftp is ~280W, which is what I can sustain for a long time without accruing too much lactic acid. I've held 200+W for hours. Just to give a baseline. A heavier person could probably do even more. A track cyclist can reach 2000+W bursts, but they are freaks.

Ottolay 5y ago

This is so cool. Viable for LED lighting in an off-grid situation when there is little sunshine for solar panels.

kitd 5y ago

A rowing machine employs a wider range of muscles and so will enable more power to be produced. Here's a DIY rowing generator that one guy built: https://www.lybrary.com/a-rowing-machine-which-generates-electricity-a-36.html https://www.lybrary.com/a-rowing-machine-which-generates-ele... He claims 100W steady output but I'm sure more is possible. One advantage of the bike over a rower is you can be doing other things at the same time, like reading a book, or tapping on a phone or keyboard. On a rower ,only passive activities like listening to music or watching a screen are realistically possible.

KennyBlanken 5y ago
Leg muscles are the largest and most powerful in the human body and it's pretty easy for them to exhaust the body's aerobic capacity. The number of muscles involved is not a limitation for longer duration power generation. There's aerobic capacity, but also glycogen and oxidative (fat) energy pathway efficiency. Experienced endurance athletes usually have quite high oxidative energy capacity/efficiency. These sorts of projects are silly because even a decent average adult male will struggle to make 100-150W for an hour.
- kitd 5y ago
  Leg muscles are the most powerful in he body, but they are not used to the extent on a bike as they are on a rowing machine. Additionally, they extend the work done by the arms and back, ie the work is not just the sum of the individual muscle movements, but the combined action. Yes, it is silly and the author intimates that in the OP and the article I linked too, but I don't think meaningful power generation is the point of the exercise. BTW a decent average male should be able to do 100W easily for an hour. I'm a (not particularly powerful) rower in my 50s and can easily sustain 150W for an hour, ie circa 120W accounting for generator inefficiencies.
- mcronce 5y ago
  You're absolutely right that projects like these are silly as anything more than a fun tinkering exercise, but that 100-150W number is a low estimate. I'm fairly small and out of shape and can produce 180W for an hour. In-shape amateurs can do better than that. Still not enough to be even remotely practical as a generation method, but substantially more than 100-150W

gwbas1c 5y ago

It's be interesting to have this wired to an electric car charger.

ygra 5y ago
I guess the more sensible option would just be to use a bicycle to get around. Simply because with the car you require most power just to get the car moving, not so much the person inside.
dahfizz 5y ago
At 100 Watts output, it would take 800 hours of biking to fill a tesla battery pack.

fuzzy2 5y ago

Reminds me of the toaster challenge video[1] where Robert Förstemann, German track cyclist, powers a 700 Watt toaster for over a minute on an exercise bike. Absolutely insane. [1]: https://www.youtube.com/watch?v=S4O5voOCqAQ https://www.youtube.com/watch?v=S4O5voOCqAQ

jdechko 5y ago
That was my first thought as well.

calvinmorrison 5y ago

One thing I think that could be changed here is a different storage medium. For example, flywheel storage instead of batteries, or compressed air storage, instead of batteries. Since batteries can't be charged faster than a certain rate, it creates a limitation. Of course, compressed air is only so useful and not so efficient to turn into electricity but, still an idea.

throwaway81523 5y ago

The main reason I want a bike generator is to power my laptop, so that if I'm going to be sucked into web browsing regardless, I'll at least have to get some exercise in the process.

amelius 5y ago

Efficiency?

jakedata 5y ago

If I were to create such a system today I would take advantage of an inexpensive (~$10-$20) MPPT (maximum power point tracking) solar controller to regulate the unruly DC output of the generator or rectified alternator. It will sweep the input voltage/amperage to find the maximum power production for a given power source. These devices will automatically charge either a 12v or 24v battery and also provide several 2a USB ports for device charging.