LED bulbs for my taillights

Considering the amazing number of times that the subject comes up, it's obviously time that we repeat our warnings about buying replacement LED bulbs for your taillights.

LED's do not work the same as incandescent bulbs. Yes, they can put out more light (although not necessarily). But what you want is more light coming out of your entire taillight unit, and that often doesn't happen by making the switch.

A stock taillight is an entire, designed assembly. And while I don't always praise automotive engineers, let's give them credit for doing good design work on taillight units. Since an incandescent bulb puts out light in almost all directions, the rear of the taillight housing can, and is, used for reflection. This fills the entire housing and, usually as well, the lens with light heading straight back to be seen by the next motorist and pretty much everyone behind your car. The lens is also designed for this light spread, with designs, fresnel patterns, etc. to maximize the effectiveness of the entire unit. And, the bulb is positioned in the housing for best results.

If you now replace that bulb with an LED bulb, a lot can get lost. LED's shoot light straight out, often with about a 20 degree spread (think a light-emitting shotgun). All of the reflection off the rear of the housing is gone and with it the effect of "filling" the housing and lens with light! The new LED bulb may not position in the same location so the lens design doesn't work the same, either - you end up with a bright spot in the middle of the lens but a lot less light than you expected from an LED bulb that looked good when you lit it up all by itself.

And finally, if you have a street rod or car where the taillight lens doesn't point straight backwards, you can add one more problem. Usually the bulb sits at an angle, that is, it's not horizontal. Replace it with an LED that's very directional and you have your taillight pointing at the sky. Low flying aircraft might see your brakes but the guy behind you won't.

And finally, not all LED bulbs are created the same. If it's a $10 bulb, it's probably not going to perform to your expectations. A quality LED bulb will typically run $20 - $40 bucks each. Buyer beware.

So unless you know for sure that an LED bulb, and a specific LED bulb, will help make your specific lights brighter, you are stuck to experiment - good old trial-and-error - to achieve your desired results.

Steve Watson, Watson's StreetWorks, http://ww.watsons-streetworks.com