Or use a small red film to cover the glass and turn it into a taillight.lionman wrote: ↑Jul 12 2018 1:17amstill cant find anything that really suits.
Isn't it a bit strange that there are quite a few USB powered head lights, presumably to run of a USB power bank, but no tail lights at all on the market?
I'm thinking I might get a small USB powered head light and swap the white LEDs out for red ones.
Not a good idea as white LED emits very little in red spectrum (it's a blue led with phosphorous coating that converts part of the blue to yellow which in combination appears white to human eye).
Or I assume I could use more LEDs in series?
If string has 3 white LED's in series (with resistor) for 12V then 5 red LED's with the same resistor would be safe.
Cheap low-powered LED lights are just at best case 3 LED's in series with resistor or at worst, 1 LED with big enough (480-520ohm) resistor to drop enough voltage for LED to survive (for a while).
Pretty much any LED tail light for a bicycle generator should work well with 5VDC from a USB port. They are nominally designed for 6VAC, but they usually are quite versatile in terms of the voltage required to light them (which varies with the speed of a bicycle generator). It's only a matter of wiring it to the plug.lionman wrote: ↑Jun 25 2018 9:35pmI would like to have a tail light on my ebike that is powered directly off USB so that when I turn the bike on, the light comes on automatically so its always on.
There are quite a rechargeable lights but they only charge off USB so not really what I'm after.
I am installing a 60v to 5v USB converter which has 4 ports on it so it would be convenient to utilise a port on that.
Does anybody know of one?
All of the LED devices I use have multiple LED. So I'm betting the resistor loss pretty low. Of all the ways I might be wasting electrons, bike LED resistor loss is way down on the list.minimum wrote: ↑Jul 12 2018 12:40pm
For example, 1 white low power LED has Vd around 3,2V at 20mA, so LED consumes 3,2*0,02=0,064W
At 12VDC resistor has to drop 12-3,2=8,8V . Resistor value would be 8,8/0,02=440ohm (larger closest value preferred)
Resistor has to dissipate 8,8*0,02=0,176W . Thats 2,75 times more than LED itself.
Sure, it's quite common here to have 100000 times more power for motor but I find it waste of good electrons; no need to contribute to global warming
Thanks for providing some links. Unfortunately I'm in Australia and most things shipped from North America have ridiculous shipping costs.fechter wrote: ↑Jul 13 2018 8:31amI didn't find any on eBay except ones with license plate holders for scooters.
The Luna one shows here, but couldn't tell if they have stock
And a couple of choices from Grin:
http://www.ebikes.ca/shop/electric-bicy ... ights.html
One of them is listed for $15.
For taillights, I use red LED strips. For a headlight I use this light: