I finally pulled the trigger on some LED headlights.
Only doing about 3,500 miles in my S3 and not a lot of them after dark, i still want to have not only some headlights that can illuminate the road, but doing it without blinding oncoming traffic.
I initially went with some sealed beam “Sylvania” headlights to replace the ones that didn’t work when I bought the car in 2010.
I wanted to upgrade to LED, but with a traditional headlamp unit and not the new ones used on Harley Davidsons and off road vehicles.
I was able to locate two brands and have always held “Hella” in high esteem. The deal for two headlamps including H4 lamps was much less than buying two “naked” headlamps, so that’s how I ended up including H4 halogen bulbs in my test.
I then ran into the complete and utter non transparent LED H4 replacement product offering. I almost ended up in analysis paralysis, but finally decided in favor of a pair of “Beamtech” LED “H4 bulbs”.
For $2.99 i bought the pro version of a light meter app for my iPhone, so I could do some light output comparisons between the three headlamps.
It is not a very scientific test, but does give an indication of which gives the highest output, although I would have expected a bigger difference. In short, here are the numbers:
The test was done with a battery on a charger and with a digital multimeter to monitor the voltage on the pin of the bulb (after any potential voltage drop over connections from the battery to the bulb).
The light was measured by moving the iPhone in a full circle and twice across the beam both vertically and horizontally, to make the measurements as equal as possible and catch the maximum light for each lamp.
Below are pictures of the light patterns and the set up as well as the test objects.
Even though the numbers aren’t as conclusive as I’d expect, it’s clear which “bulb” produces the best light. A drive test in the next few weeks will hopefully confirm this.
I agree with you about color temperature. We perceive “daylight” as brighter than yellow tungsten filaments, but I think it’s a learned influence on our visual system as opposed to a genetic hard-wired one, like ability to detect (and fear of) snakes (Jaguar content: serpentine belts )
With tungsten bulbs, brighter ones (like quartz halide) are indeed shifted upward in color temperature. Manufacturers then coated halogen bulbs with blue dyes to suggest that they were brighter still. But these bulbs actually produced less light because the longer wavelengths were blocked by the blue dye.
With the advent of white LEDs, made possible by the invention of Nobel Prize-winning blue/near UV LEDs, it became possible to shift the color temperature upwards still more. The “white” LED is basically blue, and requires a fluorescent coating to add longer wavelengths to make it appear white. It’s cheaper to skimp on this coating, and in fact the total ligh output is increased, excepting that it is mostly blue.
In fact, we are most sensitive to mid wavelengths like green. So light is most efficient at a relatively low color temperature. Sunlight itself has lower color temperature than the light on a cloudy day, but we don’t consider cloudiness to be brighter. I think that the 120V home LED lights are tending towards warmer color temperatures as the cheaper bluer ones are being rejected. Perhaps the same will happen with LED headlights. IMHO.
Did you measure the current draw on the LED vs the others?
I’m interested in the LEDs because of the typically lower current draw, as I am thinking that with the lower current it would reduce the burden on the switch… and electrical wiring.
Also do you think they’ll fit in a S1 car with its covered headlights?
I didn’t measure the current draw, but the rated wattage is about half (25W) of that of the H4 and maybe 60% of the non H4 sealed beam.
Here’s the kicker - I haven’t even had them installed in the car yet and the LED extends further back from the head light socket than the H4.
I have the modern version of covered head lights (By Marek) and have the possibility to move the head light bucket a little further out. I may get some time this weekend to carry out the last test - does it even fit in the car.
Bob, follow the link in Paul’s post to Daniel Stern Lighting. You will want to add relays to take the light switch out of the power path to the lights themselves.
On mine the heat sink does extend further than the H4 (or sealed beam), but not further than the bulb plus connector. I have an S2, and the lights fit fine. I used the Cibie housings.
Good test and explanation of perceived brightness.
I have LEDs on one of my TRs but still have the Lucas tungsten sealed beams on the E-Type. My most frequent use of headlamps is daytime driving - especially on 2-lane desert highways. In that situation the yellowish tungsten bulbs seem to be much more visible to distant on-coming traffic than the bluish LEDs.
The current draw is high of course though the 45 amp alternator easily keeps up – the TR with a 19 amp generator does not keep up with full time tungsten headlamp use - hence the preference for LEDs on that car.
I finally got one LED “bulb” installed and it fits nicely. Mind you, I have the covered headlights conversion from Marek and can not guarantee they will fit in the standard headlight set up.
Based on the dimensions and the fact that there is no plug on the back of these LED’s, I assume they will.
John,
here’s a picture showing the measurement as per your request.
I set the headlamp (Hella H4) on the table with the back of the LED H4 resting on the table surface. I made sure it was square when I took the picture below, showing the measurements to various points on the lamp/reflector.
The LED has a cable coming out of the back of it, as seen in the previous picture. I think you can discard the few extra mm ot fraction of an inch due to the shape of the light bucket.
I hope this is what you were looking for.
It is about 1/2" deeper than the ordinary H4 lamp without the plug attached, which is probably adding about 1/4", so I recon the LED setup 1/4" deeper than std. H4. I didn’t measure the original Sylvania.
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