USB Bike Charger (For Bicycle Dynamo Hub)

Hello,

here is a simple built with an integrated motorcycle charger. It will reach an average continuous charging current of 0,85a at speeds over 18 km/h and if used together with a little powerbank with pass-through function it will work very fine.

But it will not work if you connect a Samsung S24 directly to the USB (riding with more than 22 km/h it will charge with up to 1,5a !!! ...but with less you will got a lot of interuptions and fall offs) !

1. Motorcycle USB-charger
2. Connector block terminal
3. Capacitor 63v / 2F (or similar)
4. Capacitor Bipolar 63v / 220uF
5. Rectifier 700v / 5a (or similar)
6. Mini Powerbank with pass through
7. Screwdriver

Connect all parts like shown

...install at your bike handlebar and connect to the dynamo hub

The voltage of the dynamo hub is not exact 6v ! With a 28"/700c wheel, you will receive a voltage little less than your speed (with 15km/h ~ 12v or with 40km/h ~ 32v !!!). So you can try to use nearly all 6v-12v chargers. The results vary and depend of the used parts and models, there is no rule. Try and error

Various test drives with different builts and parts were made. The best results came out with the motorcycle charger when used together with a small powerbank to buffer and equalize the fluctuations of the dynamo hub. The idea can also work with other USB chargers, electronic bucks, step-down modules, with a USB car charger and even with a solar charge controller.

For the tests i had used a simple 26" Moutainbike with a dynamo hub Shimano DH-3N32, for measuring i´d used a simple USB tester and all results are based on rides at a 1,8km flat round path with one traffic light stop.

If you ride 1/2 hour with 18-20km/h you will receive something around 0,4Ah (2Wh). This is good for charging a 10Ah powerbank 4% and if it has a pass through function it can charge a mid-class smartphone 10%.

All data were captured and noted manually and in real cyclist world conditions