I joined permies becuase I wanted to share my rocket style stove design, but since I'm now a member and I saw that you guys are into alternative evergy also, I wanted to share my old doomsday exercise bike. Its very simple and made from discarded/upcycled materials, like most of my builds/projects. It is not a permenant magnet set-up, its a regular car alternator which needs excitement from a battery, which is fine because it has to be hooked up to a battery to be charged anyway. The power needs to be stored for future use, so you will need a battery regardless.

Very simple, nothing fancy, straight to business. I used it a few times for testing and development purposes, but its put away now for emergency situations, in which case it will charge a battery or bank, to be hooked up to a small inverter for emergencyt power, cellphone charging, or lighting.

My original idea was to drive a treadmill motor, they have less drag and permenant magnets. My neighbour wanted to scrap her old treadmill and she said she would put it outside for me, when I got there the next day, her landlord had taken it somewhere for disposal so I used a regular automotive alternator for emergency use.

All I did was start with a sears/canadian tire retro exercise stationary bike, removed the solid rubber tire from the wheel, mounted a compact one-wire alternator where it was out of the way, compact rather than bulky or sticking out, and functional within reach of a drive belt.

I made a small tensioner at the alternator mount, and the wheel is also adjustable like a regular bicyle for primary chain drive tension.

When the alternator is excited with 12V, its like pedaling uphill with a fat chick on the handlebars, its not easy to pedal, but I can generate 13+ volts immediately and I'm a small guy who could be more muscular. For strictly emergency situations, it works well.

The speedometer still works when you are peddalin, and the original tensioner that used to press on the solid rubber tire, still functions and presses on the drive belt for extra tension if you chose to engage it also for extra exercise fun lol.

I'm glad you like the concept.   Ive recently come up with some ideas for another one of these.   I picked up another exercise bike and I want to make another generator, however I don't want to use an automotive alternator.  This next one will have either a treadmill motor or washing machine motor for a generator.   Otherwise I will remove the tire again and place magnets around the wheel, with pickup coils or ironies coils mounted on the frame.   Thanks for following 😃

I've completed the DoomsDay exercise bike 2.0 !   I had started playing with DIY ceiling fan alternators, and I made one which turns fairly easily and produces up to 120v AC !  I'm quite happy with this latest build and I will show pics and videos of it soon.  The bike tire tensioner spins the ceiling fan alternator the same as the factory tensioner would, up against the tire, but it pedals easily.  I have powered a 110v shop light with it directly, and I've made measurements with a multimeter, and I've also rectified it once to produce DC.   I still have to upload and edit video, and I will also share so pics here and maybe on Instagram also.   It seems like a far superior design compared to the one I made last year, and it pedals so much easier.   I will have more updates and tests to come 🙂

John McDoodle wrote:This next one will have either a treadmill motor or washing machine motor for a generator.  

They are getting hard to find these days, but old tape drive motors (from the big reel to reel computer tape drives) usually make excellent low speed generators.

I still haven't uploaded or edited the video clips yet, but I'm quite happy with the ceiling fan alternator.  So far the only thing I've had to buy is a handful of ceramic magnets.  I got the exercise bike and the ceiling fan for free/scrap

here's the latest video of this project.

Cool project. I was looking for something similar and found the pedal-a-watt system which is somewhat comparable. I like the price point of this, thanks for sharing.

Mario Lazetti wrote:Cool project. I was looking for something similar and found the pedal-a-watt system which is somewhat comparable. I like the price point of this, thanks for sharing.

I'm glad you enjoyed it.  I call it the doomsday generator because it's made from 90% free salvaged junk and sometimes in certain scenarios you make due with what you have on hand.  I also enjoy sharing and building these contraptions, and if the power ever goes out, it's good for emergency.  I have wired a household outlet directly onto the ceiling fan alternator recently, which I haven't documented, but it makes it easier to plug in things such as the shop light in the recent video.   I think this could be used to supplement a small offgrid or emergency power system on cloudy days, and charge batteries only when the solar isn't keeping up.   That way you can use the batteries with an inverter to power things, and not have to pedal while you are running the electricity via battery/inverter.   But it's also amazing to me that I can plug a 110 v appliance like the shop light, and power it directly as well with no rectification or any other diodes or inverters, as I demonstrate in the video above. 

  Anyone with money can certainly purchase a similar device, but on doomsday you might not have power, or Internet, and money might be only useful for toilet paper in a collapse scenario.   Personally I just enjoy recycling and repurposing junk, learning and saving money, plus providing a simple DIY video for my followers and other people interested in offgrid and alternative energy. 

I still have yet to try charging batteries or rectifying the current to DC for charging battery banks, as intended, but if I get my hands on a bridge-rectifier or accomplish anything further I will make an update. 
🙂