MegaSack DRAW - This year's winner is user - rgwb
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Bear with me a bit as my electrical understanding is patchy and practical rather than theoretical.
Do LEDs as used in bike lights have limitations as to the power that they can cope with. I assume so. In context, my CCM trail bike puts out 130 watts through its 12 volt system. It copes with a pair of 55 watt halagen bulbs plus a 5 watt tail light, various dash board lights and indicators. Touching the brake light slightly dims the head lights at low revs. The lights are crap, mostly because of the poor reflectors. Now could I some how take a pair of modern LED lights and graft them into the bikes electrics. Obviuosly LEDs and 12 volts do mix but in a nice simple way?
You'd struggle to control the light output as the headlight reflectors won't work.
You'd need some sort of custom optic or reflector for the dip beam and another for the main beam.
You need constant current drivers rated to the current limit for the LEDs in use, and it'll be a bit more complex if you want to use multiples in parallel or series.
LEDs will "sink" as much current as you put near them, leading to thermal runaway without constant current drivers or a bloody great current limiting resistor (which is a bit of a shoddy way of doing it).
The combined point being unless you're going to invest time and effort into both the optics and the electronics you are going to be better off buying off the shelf parts.
Should be fairly easy. You can probably get a direct replacement for the rear bulb. Something like this:
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Google the bulb type and LED, or look on ebay. It'll just plug in but I'd test in on a battery first as I've had a dodgy one before.
For the fronts it'll be a bit trickier. There are direct replacement but I'm not sure how good they are. Cheap enough to give it a go, though. Failing that you could add a secondary system and hook it into the wiring. 12v is 12v. Not sure about the legality.
I wasn't planning on building anything, just plugging some light unit into the current lighting circuit. Theres my beam sorted. Not for road use anyway. Its the reflectors that I have that are useless but, for example, a pair of Gloworms would be great.
There are no direct LEDs for the front that will give a beam as good as the existing halogen bulb that are a straight swap.
You would need to rig up a whole new led light and housing to run ff the 12v system.
If you're wanting o increase the power easily, the way to go would bet to replace the lights with the HID xenon kits which have a bulb and a ballast box. They are straight fit for most lights.
I used a 12v cree LED kit attached to a relay trigger on the high beam on my scooter. Not hard.
Cbike, that the sort of reply needed. all I want to know is if cycle lights can be made to run from 12v electrics
Everyone else thanks for the suggestions but I want to throw my lights away not put new bulbs in!