LED headlight?
 

Would a led bulb be able to do hi/low beam? Like the twin filament standard bulb?
I am fully prepared to be called a noob if this is very obvious, so please go to town :D

http://www.ebay.co.uk/itm/1-X-Car-H4...item5b00eb3449

Re: would this work?
 

No

And please forget you ever heard that LED bulbs exist

Re: would this work?
 

Thanks didn't think so.
How come? I have a single led bulb light for my push bike and its fantastic

Re: would this work?
 

Ok the proper ones do work. But that one you linked may as well be made of wax and a piece of string

Re: would this work?
 

Haha yeah that was just the first one that came up on eBay for a example
So the better quality ones can do hi/low?

Re: would this work?
 

No. Unless you have individual housings for high and low.

Re: would this work?
 

I think I will accept your first advice and forget all knowledge then thanks buddy

Re: would this work?
 

I suspect that this technology will filter down to replacement bulbs at somepoint.

But its not in the bulb manufacturers interest is it.

For push bikes they're perfect, long battery life & great illumination

would this work?
 

The problem is not so much the lamp as fitting. The fittings for H4 lamps are shaped so that the different positions of the 2 filaments result in a different position of the focused beam from the light. The LED replacement doesn't have the two filament positions. It's not so much an H4 replacement lamp as an LED lamp that's the same shape as an H4.

To get LED main and dipped beams you would need separate lamps and fittings. This might be why it was an 'H4 fog light' not a headlight.

The power is possible from LED the issue is more one of cost and heat dissipation from the fitting.

Re: would this work?
 

There are Cree bulb replacements. But you need to remember that the reflector for an incandescent light source is not going to be the same as a Cree lens.