here I present to you the brightest bycicle dynamo headlight you will find on the internet . I made a custom board for the Lupine Nano, which allows the light to work with a dynamo. The light pattern is nearly unchanged from stock.
While this mod only offers low beam, the specially developed optic of the Nano allows it to reach very far without blinding oncoming traffic. The LED is kept very cool throughout the whole speed range, since the copper insert below the thermal pad of the LED has direct contact to the aluminum housing underneath.
Here you can see the luminosity, when powering the light from a SON28 hub dynamo.
Good old circuit 2 :). The more LEDs you put in series in that curcuit, the more power can be extracted from the dynamo:
1 LED -> 1.8 W
2 LED -> 3.6 W
âŚ
n LED -> 1.8*n W
While you can achieve more light by increasing LED number this way, at low speeds there will be less and less light (dynamo voltage breaks down). Each number of LEDs in series has a relatively small optimal velocity range. Also the light emitting surface gets bigger and bigger, which leads to bad beam pattern.
In my circuit there is a Buck regulator inbetween dynamo and LED. A uC measures the zero crossings of the dynamo voltage and tells the buck to pull a roughly sinusoidal current. This way the buck basically simulates an LED string, which at all speeds has the ideal number of LEDs in series. Since actual LED number doesnât increase beam pattern stays perfect at all times. At 50km/h LED power is about 10W.
Here in Germany there actually are two brands selling âhigh qualityâ lights. One of them is Supernova, which offers the âDY Proâ. This is the only commercially available light I know of, that is similar to my mod (pulls more and more power out of the dynamo as you cycle faster). Unfortunately, they only offer one really good headlight design (300+ euro) and this one uses a reflector. So the beam has noticeable dark spots.
The other (probably most premium) brand is Lupine. Some of their products use lenses (not reflectors), which are able to create the best bicycle light beam pattern presently available (very homogeneous beam pattern, sharp cut off). Also they donât use any glue in their lights⌠one can easily screw their aluminum housings open and get access to the inside. Unfortunately though their lights are battery only.
That basically is the reason why I developed a board for the Lupine Nano. Itâs build well and it is tiny (just 50 grams). One can easily open it, insert my board (with some thermal paste underneath the copper), close it and thatâs it⌠simple mod. The board and all components on it cost approx 55 euro in total (chips form Analog Devices are expensive :money_mouth_face: ) and it creates more light than the DY Pro.
I agree! But when compared to our flashlight drivers it is rather expensive, still. I had to use a special buck (LT8613), which allows to set the input current (not LED current) and that is ~14euro. Then two more 3.3V LDOs from Analog, each ~4euro⌠nearly half of component cost is due to Analog Devices :person_facepalming: .
. I made a custom board for the Lupine Nano, which allows the light to work with a dynamo. The light pattern is nearly unchanged from stock.
