Bike lights/generator question

[expjawa]

I have an idea for part of an upcoming build project that involves two headlights, and possibly a tail light. Ideally, I'd like to run them from a hub generator. However, it seems that any that I've seen provide enough current to light one 2.4W incandecent headlight bulb, and possibly a lower-wattage tail light. I have a couple issues with this. One, it isn't enough for my second lamp. Two, I don't want a dim tail light.

So, it seems like there are a couple options. I could run all the lights on batteries, but that defeats using a generator (and being battery-free). I run all the lights from a 6V flashlight battery or a multicell pack like RC cars use, but I think I'd only want that if the generator would be effective at recharging it, which I don't know about. Or, I could use LEDs to significantly reduce the amp draw, but I seem to be having difficulty finding 6V LEDs flashlight bulbs, or at least ones that have a wide enough light beam to actually make proper use of the headlight's reflector. Not much point in having a very narrow, undispersed beam. Either that or I find a suitable headlight that uses LEDs that are designed to run off of a generator.

What are other people doing about this? Can a generator that puts out 1/2 an amp at 6V keep a NiCAD or Li-Ion battery charged? Any thoughts on this would be appreciated.

 

[Bize]

Maybe strip out the LED cluster from a cheap torch? The kind that take 3 AAA cells. 3 AAAs add up to 4.5V so that's less than your generator.

 

[Meeba]

just thinking out loud, but has anyone ever tried using capacitors? somewhat like in the old ignition systems? not sure if it would werk or not, but maybe worth a try?

 

[expjawa]

I was researching that today. My thought, though, was to find a capacitor suitable to continue to power the lights for a period of time after the hub generator stops turning. That way, the lights are one when waiting at a stop sign, etc. I've come to the conclusion that I can set up the lamps to run on LEDs, so there could/should be extra power available for some other use. I've heard about people using that for powering a smart phone, ipod, etc. But that's beside the point. I'm interested more in running lights, and I could potentially power a lot of LEDs with the output from a generator...

 

[TimUK]

I was looking into something similar and my brother-in-law said he had used a dynamo to run LEDs with an old mobile phone (cell phone) battery inline which kept the lights on at traffic lights etc...I'm guessing Li-ion. I'll quiz him for details

 

[Meeba]

wind up flashlights? take one apart and see what you can adapt?

 

[deorman]

Kettler makes bikes with a hub generator and a capacitor that discharges through the tail light for a while after you stop. :|