I had about an hour before noon to work on the bike, so I put the batteries in the battery “boxes” (actually just the frame from an old UPS) and used a motor cycle tiedown to secure the batteries to the frame. I wired the motor up to the batteries. I used my dishwashing fluid covered chisel trick to remove the old, stuck handgrips and place the magura throttle on the bike. Now, it was totally operational. I took it out for a ride and found it works well! The hand grips are actually too high up and my arm gets tired operating the hand brake.
It’s a great feeling when a project works! and when it gets done quickly too!
The removable gym equipment seat makes accessing the batteries easy
The serial hybrid bicycle ready for its first test ride
After attending to some other chores, I returned to the bike for another hour or so. This time I decided to go all the way and get the generator rigged up. I bolted the motor plate down and attached a multimeter to the output. The output is actually “backwards” in relationship to the color of the leads. At full pedaling cadence, I could generate about 35 volts. Success! It was fairly easy to exceed 24 volts.
After some discussion on the Endless-Sphere forums, Fechter suggested the simplest arrangement would be to attach the generator in parallel with the batteries with a diode on the positive lead. The batteries would prevent the voltage from exceeding the safe levels for the motor controller. Fechter expected pedaling to be easy until output from the generator exceeded 24v.
Supercapacitors are horribly expensive and I didn’t feel like making a buck boost converter. So…
I grabbed a large diode and attached the generator to the batteries in parallel. I took the bike out for a spin and it behaves like Fechter predicted. Pedaling at low speed is easy, but at higher speeds the load increases, though not much. The point at which it gets harder to pedal depends on how hard the drive system is loaded. I tried going from a full stop to open throttle and also up hill. The effect of the generator is most noticeable at low speeds. Going up a steep hill, the 300w motor struggles to get the vehicle moving from a dead stop and pedaling helps.
The bike gets a lot of looks. Little kids loved it. It’s even funnier to sit at an intersection and pedal in place.
I’ll be traveling for work this coming week, but when I get back I plan to attach my bicycle computer and some other test equipment to figure out just how well this system works.
Not only did I finish the bike, but I got the ride around and enjoy the sunny day