LED bulbs in tailights

[Javi Cooper]

Thanks for the tips. What is it about the light pattern that makes the LEDs not suitable to use with a regular lens? Is it the brightness?

The delay between the 3rd light and stop lights coming on when the brakes are pressed is a little annoying, so I'm either going all LEDs or back to all incandescent bulbs if the LEDs aren't bright enough.

[PLP]

Originally Posted by Javi Cooper

Thanks for the tips. What is it about the light pattern that makes the LEDs not suitable to use with a regular lens? Is it the brightness?

No, not the brightness. The luminosity, aka light intensity.
A light may seem bright, but will not have enough power.

The problem here is the location of the light source, that is LED or tungsten wire.
Whenever you look on any light bulb replacement - the new one going in must have the light source in exactly same spot.
All the tiny reflectors, the ribs on the plastic (lenses) - they focus or scatter the light. It means that the turn signal or brake light will be intense when looking on it straight dead and to a certain angle.
If the light assembly is just filled with light, but does not have the "burning your eyes" feeling, it means that the replacement is not suitable or it was positioned incorrectly.

With enough numbers of LED chips one can achieve the same overall light intensity (number of lumen, for example 21 W 1156 light bulb is about 400 lm. One 5050 LED chip is roughly 25 lm, so you need almost 20 of them.

The problem becomes how to concentrate the light from 20 chips... especially that each of them can only light up about 120 degrees (+/- 60 from the center).

Therefore, the 2 styles I listed above somehow go around it.
I tried them in different housings and all of them had good results. Same or even better intensity than stock.
They cost much more, though.

Whatever you do - test it side by side. Do NOT use a camera as it will trick you. Better, do one side and look on both sides at the same time. If it does not look as intense as stock - do not do it.

[Zordrack]

The light emitting part of an LED is neither the same shape nor in the same location as the filament in a regular halogen bulb.

And since angle of departure is the same as angle of incidence the light will not be focused and directed correctly in a reflector made for halogens.

Personally I don't worry about that unless it's for headlights (high/low/fog) where beam pattern is really crucial.

But don't expect to get "correct" beam pattern out of a reflector light made for halogen with LEDs in it.