Recently we worked on a project where we needed to power custom electronics with electricity generated from cycling. To figure out what dynamo was most suitable for the job, we needed to characterize them in a repeatable manner.
Since we were too lazy to actually cycle on a bike ourselves, we opted to build a bicylce simulator. This way we could test several dynamo’s under the same cicumstances.
Our solution was to create a test setup driven by a suitably sized DC-motor. The motor speed can be finely adjusted and is nicely constant. The setup was built using aluminium X-shaped profiles, allowing easy adjustments for tensioning the timing belt or changing between different motors or dynamos.
The newly made bicycle simulator enabled us to gather a good set of measurements from different generators, such as output power and voltage over a range of cycling speeds with different loads.
The most important characteristic is how much power we can generate at low RPMs. Because even when the cyclist is going slow, we still need to generate enough power to operate the system and maybe even charge a battery.
After loading the data in a Jupyter Notebook we could create some nice plots to easily select the most suitable generator. The figure below shows the Frequency vs Power plot and Load vs Power plot for the winning generator.