The Blog

Sunday, December 13, 2009

Building the bicycle generator/trainer

Before explaining the image above, I'll tell a little history about putting this together.  The first salient point is that I knew almost nothing about what I was doing.  I have some experience doing electrical work for home wiring but that is about the extent of it.  Feeling rather ignorant, I poked around the web and found a trainer/generator kit for about $450.00.  The price was high but I figured that since I was so ignorant, I had no right trying to do it myself.  Additionally, I ordered a power pack which is basically a battery with an inverter in it.  The battery stores the energy produced by the bicycle generator and the inverter turns the 12 volt battery juice into 110 volt power so that anything can be plugged into it.  As I mentioned in the last post, my goal is to charge the computer with the energy produced by the bicycle generator.  That way, I get exercise and keep my energy use down by just a very little bit.  The amount of energy needed to charge the computer is not insignificant when measured in terms of how long I have to pedal!!
So, I ordered the stand with generator and it didn't come.  I finally contacted the supplier who told me it was backordered.  (My kind of customer service!!)  So I cancelled the order and went to e-bay where I found a stand and a motor and figured I could put the two together.  Along the way I got the help of one of Liza's friend's father who understands these things and helped me decide on a motor as well as helped me more recently as I finally put the unit together.
All of the bicycle generator sites told me that I needed a charge controller to prevent too much current from entering the battery and destroying it.  Made sense to me so I went to Fry's electronics and got a charge controller for about $35.00.  So now I'm into this thing for about $200.00.  Much better than $450.00.  After a very entertaining and inexpensive trip (about $4.00) to the hardware store, where the salesperson and I came up with plumbing components that attached to the drive shaft of the generator-motor, I then came home and rigged up an adjustable mounting system for the generator so that the turning tire of the bicycle spins the motor shaft.
Very excited, I hooked up the charge controller from Fry's and began pedaling away.  Within seconds, I got huge resistance in the pedals and the distinct smell of burning plastic filled my nostrils.  Damn,  I had cooked the charge controller.  Depressed by my lack of success and not really knowing where to turn, I went back to the internet and found a real person in Arizona who told me I could forget all the fancy charge controller nonsense and just hook up and watch a volt meter so as to deliver just the right amount of current to the battery.  Much relieved,  I got another volt meter (cooked the first one) and set it up.  When I plugged the generator into the battery pack, the motor started turning.  Wait!  That was supposed to be my job!   With some expert advice, I figured out I needed to put a blocking diode in the line so that the power can only go in one direction.  For $2.50 I picked up 4 diodes, soldered one of them into the line and voila, everything works.

I still haven't figured out how much power I'm producing but I know that it takes quite a bit of energy to charge this computer. I think more than two battery charges.  I don't really care though, because the point is to demonstrate that it can be done and to make me feel like I am not just exercising for exercises sake but because I also want to make electricity.  The side benefit of teaching my kids that their energy can be turned into electrical energy is also very cool.

So, the photo.
RIght hand side you see the rear wheel, the stand, the mounting plate and the generator.  There are 4 big bolts that hold the mounting plate to the stand by squeezing the plate onto one of the stand's uprights.  Three hose clamps hold the generator to the plate and offer some adjustment of the shaft in relation to rear tire.  You can see the plumbing fixtures I found that attached to the shaft.
On the left you see the battery pack that stores the energy produced and has the plugs in it for AC power out.
In the center you see the volt meter putting out almost 15 volts which is about right.  The little black thing is a diode that is exactly like the one that is in line where the wire nuts are.  When I pedal, I put the volt meter where I can see it.  It turns out that the battery provides resistance so it is easy to know when I'm pedaling enough.  When pedaling becomes difficult, I am right at the correct voltage.  To try to pedal harder is a real challenge and since it's bad for the battery to put too much current in, everything works out just fine.


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