You need to consider the consequences (was Re: I need to amplify my current)
I guess it's a matter of taste. I know my NSX customer wants them really bright. So people might like them a little bit dim also.
No, it really isn't a matter of taste. It's a matter of safety and of law. These aren't toys we're talking about, they're safety devices critical to crash avoidance. No matter what your NSX customer (who probably knows very little about automotive lighting and crash avoidance) may think he wants, no matter how much cash he's throwing at you to build him a pair of what he seems to consider cool playtoys, a vehicle's signal and presence lights (park, turn, brake, marker)
must work the way they're supposed to work, or they're unsafe. Brighter is
not necessarily better.
Brake lights and red rear turn signals need to put out between 80 and 300 candela straight back between 5° left and 5° right, at least 40 candela between 10° left and right, at least 70cd straight back between 5° up and 5° down, and there are other intensity requirements at other points in the beam (the requirements are structurally identical for amber rear turn signals; only the intensity values differ). And the ratio between the bright red brake mode and the dim red tail mode needs to be at least 5:1 at the primary points and at least 3:1 at the secondary points.
And not only is it crucial that the intensity be within the proper limits through the entire relevant range of vertical and horizontal angles to convey the correct message quickly and unambiguously to observers at any angle to your vehicle (not just straight in front of or behind the signal), and not only must the intensity ratio between bright and dim modes be correct at all angles (for combination brake/tail or park/turn lamps), but the effective projected luminous lens area must not be reduced below the legal minimum. EPLLA refers to the amount of lens area actually significantly lit up when the lighting device is active. You might have a brake lamp with a total lens area of 64 square centimeters, but if you stick a 4cm-by-3cm array of LEDs in there, your EPLLA is going to be only about 12 square centimeters, not nearly enough to meet the standard.
All of these requirements are to make sure the lights do their job and convey their message clearly in all ambient conditions (day, night, rain, shine) without dangerous glare to those you're sharing the road with. Just looking at homemade lights and saying "Yep, they look about right" or "Wow, they're super-duper bright, just like my customer wants 'em!" doesn't cut it, especially not with insurance adjustors, judges or juries…remember, you are putting yourself squarely within the chain of liability when your homemade car lights contribute to a crash. If you are smart, and you don't have a few tens of millions of dollars' worth of appropriate liability insurance, once you complete the lamps you'll want to have them tested for photometric and physical compliance with all applicable provisions of Federal Motor Vehicle Safety Standard 108.
Calcoast is one of several reputable labs equipped to do such testing. That way, assuming your lamps pass, you are protected from the results of a crash that might call the vehicle's lighting system into question.
Note that FMVSS 108 is the regulation you need to comply with. It incorporates various provisions from various SAE standards, but the SAE standards themselves do not carry force of law, and compliance with any SAE standard does not guarantee compliance with the actual legal regulation.
:sigh: :shakehead
