Dynamo Rear Light
INIFINITE LIGHT FOR CHEAP
I was looking for a less expensive option to the K-light dynamo rear light. A light that would keep flashing a long time after pedalling and obviously also flash while pedalling. I found this light, designed for dog collars, that has a small, capacitor-like, battery which can charge while the LEDs are functional. This is perfect for a small rear light that never goes off. While you ride with a dynamo, the battery charges up in the USB port of the dynamo system. Simply push the power button to light up the LEDs whenever you want. Whether you are completely stopped or pedalling, the LEDs will always have power.
The dog collar light, disassembled
To create a Dynamo rear light, that is “waterproof”. Simply unsolder the micro-USB connector, strip a USB extension and connect the positive and negative wires of the cable to the positive and negative terminals of the USB pads on the PCB. Once connected, you can glue the cable with the PCB in the plastic case and shut it closed.
Advantages:
”Water resistant” by sealing the USB cable entry point with hot glue, never got any water in;
Cheap alternative to the K-light rear light system. Cost me approximately 10$CAD (I already had a USB extension laying around);
Keeps charge for a long time after pedalling;
Also lights up while charging.
Drawbacks:
No reflector system. As an improvement to this system I would put mirrors around the LED. Changing the casing, to project the red light to be seen from further.
USB extension soldered on the light PCB
I have used this light setup during the Transcontinental Race, and other smaller bikepacking test rides. It has seen rain and mud, and never stopped flashing! I use a SonDelux front dynamo hub on my Hunt wheels with a K-light dynamo system for front light with a switch to toggle the front light on. The USB ports in this system are “Always on” so it keeps power to the rear light and whatever else I plug into (power bank, GPS, phone) at all times.
Light assembled on USB cable. The battery still has enough power to light up the LEDs, several months after the last charge
The bike in daylight, showing the Dynamo rear light on top of the seat bag and the K-light front light connected to the front SonDelux hub on the Panorama cycles Katahdin carbon gravel bike
The Dynamo rear light is attached on top of my seat bag on my Panorama cycles Katahdin. This picture was taken at the start of my CSBR900 FKT.
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