Ed Scherer

In a posting about three years ago on the topic of LEDs for brake lights, tail lights, etc., I said (among other things ):

Note that next to the last line: "I've been through this cycle at least three times now."

Well, make that four times now.

This time, I've taken the time to put together some simple test set-ups to judge the relative merits of a number of LED bulbs — particularly as it relates to their use in our 87-95 tail light assemblies (it might apply equally well to earlier model year tail light assemblies, but I don't have any to test so I don't know for sure).

I'll give you a little hint as to what I've got; what I'd like to know is whether or not to take the time to compile it into a useful write-up. It would take a few hours, so I don't think I'll do it unless I get the sense that it's of value to some of you guys and gals.


The bulbs I evaluated are these (for now, I'll just show images, as they're typically available from more than one source and if they look identical, they probably are actually the same units). I believe I've obtained the most promising bulbs available over the last few years up to now, but I might have missed some. There are some bulbs I've evaluated that just are nowhere close to being bright enough; I've just ignored those for the purposes of this evaluation. Note in particular that having loads of loads of LEDs in a bulb doesn't guarantee brightness. In fact, some of the best bulbs have just 1 or 5 LEDs. Some of the "zillion" LED bulbs are also the most inadequate.

(If you click on some — but not all — of the photos below, you'll get big versions; I've tried to keep these reasonably small here.)




Test #1 was done with an BAY15d base (1157-style) bulb test-rig that would let bare bulbs project against the wall at an angle; this allows the beams of two bulbs to be compared. It is not at all conclusive, as it is strongly biased against bulbs that project much of their light to the sides (and there's a lot to be said for that when you're using the bulb in a traditional reflector assembly).





Bulb test rig version 2 was used on some of the later Test #1 tests. It includes some rectifiers (diodes) to prevent a current backfeed that was causing some of the bulbs to interact (which caused some of the bulbs to go into "bright" mode when only their "dim" mode circuit was activated).



An example of one bulb comparison (both dim and bright mode compared):






Test #2 was done with the 1157 bulbs installed in the brake light position in the tail light housings, and then letting them project against the wall. IMHO, this is probably the most significant test, as it allows the overall brightness and beam pattern to be viewed, with the light gathered and dispersed as it actually will be when the bulbs are being used for their intended purpose on our cars.





An example of one bulb comparison (same bulbs as in the previous examples, and again both dim and bright mode compared):






Finally, test #3 was just turning around the tail light assemblies and from test #2 and see what they look light straight on (i.e., camera in same plane as the light assemblies). This turns out to not be a very good test for overall brightness (test #2 is better for that), but it is pretty good at revealing the "hot spots". IMHO, nice even lighting is preferable to uneven lighting, all other things being equal.



An example of one bulb comparison (same bulbs as in the previous examples, and again both dim and bright mode compared; note how different the hot spots are):






And... I measured current flow for each of the bulbs, which also revealed some interesting information (e.g., certain bulbs that were supposedly x watt bulbs were really nowhere near x when measured, assuming that P=I×V applies to LEDs as it does everything else ).



If I do a more comprehensive write-up, I'd include all the tests, with the photos of all the comparisons (I always select a "reference" bulb for the left side and then compare to all the others on the right side), along with comments on the pros and cons of each bulb. I've come away with my own preferences, which I'd probably reveal, too. Oh... and one of the bulbs I showed above I just got today and haven't put it through the tests yet, so I've got a little more work to do anyway. I fired it up briefly, though, and it did look promising. Need to wait for darkness before doing additional testing (I'm doing the tests in a garage with windows that I can't easily cover).

Leon Speed

We're mostly all geeks here, so the more details and pictures, the better!

Ed Scherer

Oh yeah... as a bonus, I've been messing with LEDs for the back-up lights, too. Didn't think I'd find any that were bright enough, but I think I just might have (got one in today that looks promising). It hasn't been the focus of my attention, but I might have something to offer on that front, too, later. I've done some evaluation of these, but probably not enough to share quite yet:





Example of one of the LEDs vs. P21W incandescent:

Jadz928

Ed,
Nice rig!
I'd followed your old thread closely and have referenced it many times.

The reason I continually shelf this project is two-fold: one, researching current tech is a moving target (as tech improves), and two, my understanding was the current tech (1-2 years ago) was marginally equivalent.

I'd be very interested, esp if you believe LED tech available now exceeds OE incandescent.

On another note, LEDs are pricey, esp the newest/best.
I believe cost would not be a concern for most, if folks would feel comfortable that rear light safety is not only equivalent, but improved.

Thanks for sharing!

borland

Ed,

For my tail light and third brake light bulbs, I'm currently running 7 watt LEDs from VLED.com. Very bright when I hit the brakes, with a total of seven (7 watt each) brake lights. They are not cheap, but worth the price IMHO.

My bulbs look like this but in both 1157 and 1156. But VLED.com now has a never version of the 7 watt bulb in 1156 and 1157.



Here's the latest 7 watt design...



I'm still running rear incandescent turn signals and backup lights. The rear turn signals in incandescents, mostly because of the instrument cluster signal problem.

Jadz928

Cool, something to geek out to tonite!

This is a real bonus. Wouldn't effective rear backup lighting be fantastic?
Most car's backup lighting are only worth other's ability to see you.
Completely worthless to see where you are going, while backing up at night.

123

Very timely and interesting thread as far as I'm concerned. I've just recently started thinking about making some changes to external lighting using LEDs, and had no idea where to start other than randomly buying and trying various LED bulbs. Thanks for taking the time to post results that have been found.

bigmac

I would sell my first born for a set of LED's That fit where the Fog/lights fit. Saw some nice sets @ a Nissan aftermarket location. We need someone like Carl or other venders to Come up big and make these available to us.

Jadz928

$80/pair (2 total)!
This bulb appear pretty long, almost 2 1/4" total. I'd be concerned about fitment and hot-spotting.

pcar928fan

Do these set off the dash warning light?

Ed Scherer

Hmmm... there's one I haven't tried yet.

Just out of curiosity, have you ever measured current flow on those? The reason I ask is that I have reason to believe that a lot of fudging goes on with the "specs" or at least "wattage ratings" provided by the folks hawking these bulbs. I was kind of shocked at what I found with one "7 W" bulb: nowhere close in brightness or wattage when I tested it. In fact, that's one of the things that motivated me to start evaluating these bulbs more comprehensively: it was becoming increasingly difficult to trust the information provided by some of the sellers (FWIW, I find superbrightleds.com to provide good technical information that's consistent with what I find with my own testing, but I either can't find the same quality information at other sellers or whatever they do provide isn't necessarily accurate).

I contemplated getting some light readings off of the bulbs I was testing, but I'm really not sure at all if there's really any reasonable way of doing it due to the radically different beams they cast. I really think that the "test #2" I showed above is the best all-around test I could come up with.

IMHO, there are a lot of things to consider when choosing the "best" LED bulb. Brightness probably being number one, but even/appropriate distribution of light given the housing it's used in comes in a close second. I've actually chosen different bulbs than my preferred ones for the 928 in another vehicle that has clear lenses on the light housing.

And... thanks for your previous efforts on the LED lighting front; I've got a bunch of NAPA 680-3296 sockets ready to go to do the "brake lights across the whole bottom" mod that you described in your S4/GT/GTS Brake Light Upgrade Mod thread.

Herman K

Sets of models only

Ed Scherer

BTW, something else I noticed while I was conducting tests: a couple of the bulbs (that I got a couple of years ago or so) suffered from a strange problem where when they were wired in parallel with other bulbs (i.e., their bright circuit connected to the other bulbs bright circuit and ditto with the dim circuit), they'd go into bright mode even when only the dim circuit was activated. Some kind of current was flowing from the dim circuit to the bright circuit somewhere.

I suspect (but didn't take the time to track it down) that the newer bulbs have diodes/rectifiers built in that prevent this.

It explains, though, some weird interaction problems I remember having with mixing LED bulbs (front/back) where, for example, the front turn signals wouldn't work properly: they'd stay on bright when the parking lights were on.

I'm pretty sure that this could be rectified () by using some external rectifiers/diodes (1N4002 or whatever), but I think I just avoided those bulbs when the problem occurred a few years ago.

Next time I'm messing with these, I'll remember to note the bulbs it happened on (I think it was the two older round-lensed Luxeon based ones) and see if the external diode solution will work.

Jadz928

Good condender for a backup light

Jadz928

Ed,
I see a pic of what appears to be the same LED, with and w/o forward facing plastic lens/diffuser.
What is your general take on this design element? I assume it is intended to diffuse hot-spots. Effective?