| > > What are the pros and cons of using red LEDs instead of | > > light bulbs for the center high mount stop lamp (on the deck | > > lid) for an Intrepid? | >
| > Pro: The vendor who sells you the LEDs makes lots of money. | > Con: Your center brake light no longer works as intended, particularly | > from the standpoint of visibility angles (horizontal and vertical). | >
| > Canned text follows: | >
| > LED signalling lamps (brake, tail, turn...) are appearing on cars, and are | > widely used on trucks, but it really is not a "retrofit" item in the sense | > you're thinking of. The rear lamps of your car rely on a point source of | > light (glowing filament), collecting that light with a parabolic reflector | > and dispersing it with pillow optics in the lens. An LED is a vastly | > different *kind* of light source. Unlike a glowing filament, it does not | > produce light in an even sphere. Instead, it projects a very narrow beam | > of light in ONE direction. That's why these so-called "LED retrofits" | > consisting of a 1" diameter matrix of LEDs on a bayonet or wedge base are | > unsafe; there's no way you can get enough light through a wide enough | > angle (horizontally and vertically) to create a safe and legally-compliant | > lamp. There are other considerations, too -- it is tricky to get the | > right ratio of bright-to-dim intensities both on axis (straight behind the | > lamp) and also through the entire vertical and horizontal beam spread. | >
| > Look at the optics of the Cadillac DeVille that has Hewlett-Packard LED | > tail/brake lamps, or the high-end Mercedes S-class that has LED brake | > lamps. You'll see some *very* fancy optics used to coordinate the light | > from a *LOT* of LEDs to get everything right in terms of brightness in | > both dim and bright mode, uniformity of brightness throughout the | > visibility angles required by law, ratio of intensity between "bright" and | > "dim" mode, etc. These kinds of optics are not something you can kludge | > in your garage, let alone achieve with these unsafe "retrofits". | >
| > The important thing to remember is that you're working with safety systems | > everyone else on the road relies upon. | | Good information, thanks for taking the time to reply. It doesn't sound | like that good of an idea, although I admit I first became suspicious when I | saw one model of LED 'bulb' that was supposed to fit half a dozen of bulb | numbers. Who standardized bulb sizes with common numbers? SAE? | | Still, I wish Chrysler had used LEDs for this application, particularly for | the quicker illumination and every time someone slams the trunk shut the bulbs | get slammed too. I do see a lot of non-functioning CHMSLs and eliminating a | bulb that can (will) burnout could be a design improvement. Perhaps the | technology will be better/cheaper in the future. |
I thought that impact shock wasn't much of a problem unless the lamp filament was illuminated. I wonder how often the trunk lid is closed while the brake light is on (probably does happen occasionally).