Series Hybrid Motorized Bike

I am designing a system to motorize my bike, but I really don't have enough money for it. I have been thinking I would like to use this engine for quite a while, because it's cheap, light, and OHC. There is a centrifugal clutch for it, but it costs $85, so I've been trying to design a series hybrid system instead. Considering that these motors cost only $6, it seems perfectly feasible to make something cheaper this way, but there are ways I can think of to possibly make it even cheaper. Here comes the technical part: my original design has two of the motors hooked up to the engine at double speed as generators, making 12v. Then there would be two more of these motors traction-driving the rear wheel. The problem with this is that the gear reduction is expensive. My new design has the engine directly driving only one generator, making only 6v so that I would have to have as many as 8 motors driving the wheel (opportunity for AWD?) to pull enough current to get full power out of the engine. Here's the problem: I don't know if the generator will be able to handle that current draw. Considering it would only have to do it for a couple seconds, do you think that one of these motors (working as a generator) could handle 400 amps surge?

Other information: this will not see much low-speed operation. Geared to top out at about 25mph, it will probably spend most of it's time going 10-20.

yourcat (author) 9 years ago
Sorry, only 45 minutes after posting this, I found the easy fix: have several parallel circuits that I can engage or disengage separately. That way, I can start out using only the current draw of one motor, and then as I get past stall, I can engage more of them. Not to mention that a lot of my math was wrong: at any more than 120 amps, the engine would lug badly anyway. Also: to get more of the engine's capacity used at high speed, I would just add more motors as an upgrade, just not connect them at low speed. Please post any ideas, and thanks!