GalFisk said:
bowlofsalad said:
I've decided to shave most of what I have down to this. I suggest you get a second bike, keep the electric stuff on bike A, get a small gasoline motor and have that directly power bicycle B.
The jack of all trades is master of none.
I disagree. The gasoline engine for vehicle propulsion is the one that attempts to be a jack of all trades; it needs to run reasonably well under a wide range of speeds, loads and throttle settings. A gasoline engine designed for driving an electric generator needs a much more limited range, and can be made more lightweight and efficient.
If this actually has been done with the gasoline engine running this generator or not, is a different question.
The charging process is far from perfectly efficient, there is a lot of losses in the conversions going on, more than you might realize. The generator would need to be larger and heavier than just a gasoline motor would need to be to output the same amount of power, the generator is doing more than just turning a shaft. If we were just comparing the generator to a small gasoline conversion kit, the gasoline conversion kit would come out lighter, but there is also the battery, charger, and electric motor to add to the weight of the generator concept. The generator concept comes out to be wildly heavier, it's strange that someone would attempt to argue otherwise. Some folks use gearboxes, or mid drives for their gasoline motors that over come the issues you mentioned. Electric motors have efficiency curves at various RPMs as well as torque output curves at various RPMs, similar principles and issues relate on either 'side'. Try not to mistaken me for a gasoline lover, I am merely trying to present an idea with equality.
For power to go from the gas motor, to the inverter/converter, charger, battery, controller and then to the electric motor is expensive, very heavy, overly complex and far from efficient. You'd get wildly more power to the wheel just driving the gas motor alone with a direct chain or a mid drive type setup.
To me, the only advantage that comes from this generator/electric bicycle idea is the ability to shut off the generator while riding through paths that restrict motor usage. It's an interesting idea (one I considered myself many years ago), but it comes out to be a bad one. I'd just cut out the middle man and go pure gas if I couldn't handle finding an outlet and the range limitations.
If it were up to me, I'd just have him put a bunch of batteries on a trailer behind a recumbent trike and allow him to discover how happily just about any place will let you plug in your charger, especially if you are buying something or offering them a little cash. But I suspect his goal is to not have to worry about stopping to charge a battery, which is why I made my suggestion, ditch the generator and go pure gasoline. It'll be lighter, more efficient, and all around better with one or two exceptions.