I have been wondering if PedGen1 would really fit in a suitcase? If it would not fit, what other parts could I saw off the bike frame?
We thought it would be fun to take a break from charging the cell phone and do something a little lighter! The picture above shows the PedGen1 being used to power a string of LED lights.
Over the weekend, I made progress! My husband helped me install a digital speedometer and determine the target speeds for specific voltages. Then I pedaled for 2 hours and charged a hand-me-down iPhone (see video below). Here are some pictures of the speedometer installation process. The gap between the sensor and the magnet was too large at first, so I cut a piece of cork to fill in some of the excess space. Here are the speeds and approximate corresponding voltages (without the voltage regulator attached): 8 mph - 32 volts 10 mph - 40 volts 11 mph = 45 volts 12 mph = 48 volts 13 mph - 51 volts 15 mph - 58 volts 16 mph - 62 volts 17 mph - 65 volts To produce 15-20 volts, one must pedal at 4-5 mph. The voltage regulator will step the voltage down to a steady 14 volts. However, I noticed as I pedaled that the green light on the inverter did not illuminate until about 4.6 mph. To charge the cell phone I tried to pedal at a steady 5 mph. Occasionally the inverter went into thermal shutdown. When this happened, the load decreased and the resistance to pedaling dropped noticeably.
I keep reminding myself to view this whole project as an experiment. That sounds better when things do not work out as I had hoped - like the speedometer, for instance. At 11:30 last night I was taking apart the PedGen, trying to install the analog speedometer on the small sprocket. I had to bend the peg on the speedometer to make it fit the small radius of the sprocket (since it was intended to fit on the much larger radius wheel). Adding the extra layer of the speedometer caused the space between the two arms of the bike frame (on either side of the wheel) to become very tight. Once I put the bicycle back together with the speedometer in place, it was so tightly packed that the speedometer would not turn freely. Then the speedometer peg, that was hooked on the sprocket, actually began to bend. At that point I decided some sleep would be beneficial. Now it is the next day and I don't have any brilliant ideas for making the analog speedometer functional. It seems like I would have to bend the bicycle frame in order to widen the gap between the two arms that attach to the wheel. I am not willing to do that just for the sake of avoiding a digital speedometer. I am also concerned that soon the analog speedometer will be ruined and I will not even have the option of returning it. I admit, I was feeling relieved to trade in my analog speedometer for a digital one. I am ready to overcome that obstacle and move on to timing the process of charging a cell phone and a 12-volt battery. I went to the Bicycle X-Change over my lunch break today. I explained to the bicycle technician that I either need to reverse the direction of the speedometer cable or switch to a digital model.
I am not off the hook yet - the technician scrunched his brow and thought for a few seconds,"So, you are not shifting gears with this thing?" "No." "I think you could install the speedometer by hooking it onto the small sprocket [instead of on the actual wheel spokes]." As I left the store, he commented, "It's a good thing you found someone who is used to inventing." " I know I am fortunate to have you as a resource." I smiled as I left. I hurried home and removed the axle peg on the chain-side of the wheel. I grabbed my husband's socket set, but did not have time to take off the nut that attaches the bicycle frame to the wheel. Hopefully I will have time to do that tonight. Now I am curious to see if this plan is going to work! I worked with the speedometer last night, trying to determine the best way to attach it to the bicycle. First, I tested the speedometer to make sure I was orienting it so that it would turn the correct direction. As you can see in the video below, my husband helped me connect the speedometer cable to a drill. When the drill ran counter clockwise, the speedometer needle moved in the correct direction - reading as high as 10 mph. Thus, the speedometer would have to be mounted on the chain-side of the bicycle - which does not seem possible. Could the speedometer be mounted directly on the generator - on the peanut butter jar lid? I am not sure if this would be possible or worth the trouble. Perhaps I should just use a digital speedometer. It would be cheaper and easier to mount; however, it runs on batteries. A few things for me to ponder... May 19, 2014 - I have not found a good way to mount the analog speedometer, so I am going to return it and use a digital one. It is not ideal because it requires batteries. However, I hope the person who ends up managing the PedGen in Haiti will become familiar with the ideal pedal pace and eventually will not need the speedometer. |
AuthorCatherine Johnson is a student in the Masters of Science in Environmental Studies program at Friends University in Wichita, Kansas. Archives
July 2014
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