Saturday, September 5, 2009
Why Electric Bikes?
This is my first post in the site. I'm Michael and have been building electric bikes for a couple years now and this project has given me the opportunity to step it up a notch. I love to tinker with things, always have. How this all started was that I would ask the question whenever I needed to go somewhere could I take the bike instead of the car? First I found that usually I would take the car because I needed to carry something, so I started riding an Xtracycle, then I noticed I would take the car because I didn't like peddling up the hill on my way back home from town. So I started with very small hub motors that gave me enough help to make most of my local trips very easy even with a load on the way home. Then being a good motor head and inventor at heart I wanted to improve on the performance of the original stock ebike conversion kit that I used (the Bionx). That system is actually very good in many ways until it gets old and starts to have a mind of it's own and is not really fixable as the motor and motor controller and battery are all integrated and the dealers don't really know how to fix them beyond buying a new battery / controller or console at a very steep price.
So for now what I am working on is biulding a team to help with the development of a very sturdy reliable bike that will make it across the US at a rate of 120 miles between charges. That can be done first by building a very efficient drive system and then building a very energy dense battery (at 80% discharge: 1620 watt hours / 25 pounds) and peddling a lot. Without peddling the bike would do perhaps 70 or 80 miles at the same average speed. Electric bikes are really for short trips and the rider can choose how much to peddle depending on how much energy they have, how hot a day it is or how far they need to go on a charge.
I like to use the image of the film Apollo 13 and see first how little energy we can use to get down the road, it's really a game, but last time I checked the planet was a sphere and a finite system like the Apollo 13 space capsule. So the first order of business is to see how much energy we can not use, like what you would do if you are planning a solar system for your house, reduce the amount of electricity you need. It's far cheaper to start with efficiency and build less PV capacity than it is to live by the old adage brought to us by the Nuclear Energy Commission moto: "To Cheap to Meter". I could go into details about how the battery systems are build, but some of the information is, for good reason, protected IP and other information is open source. We are using equipment that is all open source and sometime a bit crude, but the only way that this or any other technology will be available for prime time is if it is made in large enough quantities. Since it is by definition a "sustainable solution" the entire process from cradle to grave need to be looked at. For example, I would opt for a battery pack that can easily be fixed if one cell in a group of cells goes bad. This may cost a bit more to build, but perhaps not. It's a matter of good design and a huge impact on the sustainability of the battery pack when serviceability is designed into the system. When profit and "economic sustainability" are at odds, our challenge is to keep that inquiry open and find solutions that consider the true costs and market realities. One point of this ride is to open up the question in people's minds about the true cost of the things we use, remembering that we are on a large version of the Apollo 13 space capsule. It seems to me that the electric bike is a good platform to play with this question.