Bike generator

Before going to build big thing i wanted to create something as proof as concept. Generating electricity with bike seemed to be the simplest and cheapest.

I went to car junk yard and picked up opel kadett car alternator for $8 and used 55Ah car battery for $20(at shop was told battery is just charged and ready to be installed to car, actually at home i measured under 10V eg battery was as dead as could be). Also i have at home 300W inverter that creates 220V 50Hz from 12V DC. I had at home mountain bike that i haven't used much. Also i picked up some 2mm thick metal plates, drill bit, mains wiring from hardware store and thats almost all that was needed.

To turn ordinary bike into generator is needed stand to lift up the rear wheel, secondly is needed generator to be connected to pedals. One industrial strength bike stand cost like $400 including shipping.


I created stand out of thick enough wood. I created 2 T-shaped pieces where upward facing part is thick enough. For connecting 2 pieces of lumber is used metal corner pieces. Wood stand was connected to bike frame with easily bendable metal strip used connecting gypsum carcass to walls, place the strip and just screw in a few screws with cordless drill.

Alternator itself was connected with holed metal plates. One end was connected to wood stand and then i just placed plates and cornered plates as the way alternator should have been. I drilled holes to better places and connected it with screws, bolts and nuts.

First setting connecting alternator was that i removed tyre and improvised drive belt from string. Best homemade drive belt i managed to build was created from multithreaded string. Each thread could be tied together separately and this made knot to be the smallest. Line was covered with duck tape to increase its traction.

Everything connected it was start to test. Peddaling with fastest gear successfully started up alternator and it started to ouptut bit over 14V. When alternator was connected to battery it gave out briefly 5A of current, pedalling bit more and again biref spike of current. What turned out is that when alternator reached its cut in rpm and it started to put power out then string started to slip and alternator slowed down so much that it was not working anymore.

I rebuilded my bike rig bike tyre went back on, attached toy car tyre to alternator and pushed this against bike tyre. This seemed to have better trackion than with strings and actually it was much easier to peddal without load. After wiring alternator back up similar problem happened. When alternator cuts in it gives peak of current and then nothing anymore. I tested with open circuit while measuring voltage on alternator terminals. It produced nivcely 14V and then after a while peddalling went harder and voltage dropped down to around 6V.

There are 3 terminals on alternator. 1) ground 2) + output 3) connection with marking +D, this must be excitation connection. Between output and ground is capacitor, disconnected one end and checked, this was holding voltage. When letting some current to excitation pole alternator cut in pint was at lower rpm. This all seemed like there is some short circuit within alternator as even if not wires are connected it consumes power and puts nothing out.

Brainstorming

I will write down subset of ideas i have for future and i will implement some of them sooner or later if these ideas survive my limited budget, deeper analysis and time trials.

1) Set up weather station that measures wind and sunlight.
2) Recharging electric scooter/bike/car
3) Generate electricity with exercise bike or regular bike with training stand
4) Set up solar panel to generate electricity
5) Erect small wind turbine to generate electricity
6) Use self generated electricity to heat water in boiler
7) Implement grid-assisted power system that switches (seamlessly) to grid power when batteries run empty.
8) Connect home power station to grid (on-grid tie system)
9) Produce hydrogen gas for using in fuel cells or direct combustion in car.
10) Get property near water stream and build little water generator.

Windspeed analysis

Before setting up wind turbine it is generally good idea to make sure how much wind is actually blowing in your area. Small wind generators typically start up with wind at around 2,5 m/s and reach their rated output at windspeeds of around 12-13 m/s. I found world wind maps and based on this data my location looks quite promising, having average winds 5-10 m/s. From other hand, when looking detailed estonian wind map the average windspeed is not so promising at all and averages to 3,5m/s.

To get adequate information about wind speed adjusted to local conditions wind speed should me measured. Cheapest anemometers can be bought around $60 but i found great proffessional weatherstations including anemometers . These cost from $160 but can be bought cheaper from ebay etc. Some models from La Crosse Technology feature possibility to upload weather data do websites in realtime.

Most probably i will get myself one of these as soon as i have found the right model and found the place where it can be bought cheap.

Loadbalancing

As investment into wind turbines and solar panels is quite expensive then money spent must be used efficently. While being off-grid its not efficent to build too big generator as lot of power goes to waste and in other hand having too small generator power may just run out when it is most needed. Also the factors that must be considered is that you never know when there is wind and when not.

This all makes finding right size generator for your usage quite difficult so that you use your money effectively.

One of the best options for solving this problem is to go on-grid and it is actually possible in Estonia even with small windmills but what has do be done for that will be revealed in one of the next posts.

Starting out

I have been thinking for some time to start using green energy that is solar and wind power. I find that there is not enough information available for enthusiasts. Going completely off-grid is not an option and there should be found optimal balance in using green- and grid energy and FUN for reasonable price.