LED H4 Bulbs

[Trouble]

So I bought a set of H4 LED bulbs for my 1987 Porsche 944 And after I installed them to see if they worked, (They Did) I lost the low beam lights… they work fine with the High beam. I also have proper voltage at the plug an I’m running the separate harness and relays off the alternator, These seem to be Quality LED’s with a built in resistor, Any idea what could cause this to happen all of a sudden??

[Tom]

Did they work initially?

[Arne2]

Being a bit of a lighting nerd, I'm going to guess that the low beam diodes have failed due to thermal overload.

LED capsules (bulbs) do build up heat. Some H4/9003 format capsules have large finned heat sinks or even cooling fans attached to keep the heat away from the actual diodes. Unfortunately, most of those capsules will not fit in the confined headlight bucket of a 944, and the headlight bucket itself doesn't have much ventilation either. Low beams are the most used, so that's where heat damage occurs first.

You note that they "seem to be Quality LED’s with a built in resistor." I see two problems with this statement. One is that the resistor you mention (which is there to try to prevent cars that can detect lamp failure warnings from triggering due to the low draw of LEDs) also creates heat, making the issue worse. The other is that most of the parts that make a 'quality' LED capsule can't be seen, such as the quality of the internal circuitry. Lots of makers can build something that looks quality from the outside with nice machining, casting and finishing. But making them durable is another thing entirely. I've yet to see a LED replacement for halogen that I'd want to trust to have the lifespan of a name-brand halogen bulb.

And that's not even considering the fact that many (most?) drop-in LED capsules don't shield or emit the low beam pattern as accurately as a true H4 bulb. Same with HID conversions.

These reasons are why I still run halogen in my cars that use them.

[Trouble]

Yes Tom, They DID work initially, But only for about a week, I personally LIKE the look of the LED lights on a 37yr old vehicle, BUT until technology improves I’ll be putting my older Halogen Bulbs back in…. I also WANTED to do my fog lights but to do it right I want to remove the housing and resurface the reflector with some aluminum foil tape, I’ll save the H3 bulbs in case I run into the SAME issue…..

[Arne2]

If the 'look of LED' you are wanting is the less-yellow light output, consider name brand H4 bulbs with the tiniest blue tint to the glass envelope. Don't get heavily tinted, blue tint reduces overall light output and causes more glare to oncoming traffic. You just want a very slight tint. Untinted bulbs give the best light output.

My go-to bulb brands are Sylvania (Phillips), Osram, and Narva.

[Gaspowered]

For other people reading this thread, @Arne2 knows about what he writes.
If anyone would like to venture further down down the rabbit hole regarding halogen vehicle lighting, I would suggest a few minutes of downtime reviewing this website; https://www.danielsternlighting.com/

Cheers

[J-Dub]

I recently put LED H4 bulbs in my existing H4 housings in one of my cars. The light output seems brighter when I shine the light against a wall but when I am driving at night I am not sure it is better in the usable type of way.

I have a road trip coming up with that car where I will do a significant amount of night driving. Still trying to decide if I will switch back to Halogens or not.

[Arne2]

The reason the output doesn't seem better is that the LED capsules can't accurately mimic the precise filament location and orientation of a halogen bulb. And the H4 lamp housings that we put the LEDs in have lenses and reflectors that are precisely engineered to direct the light output from that bulb filament. If the LED output is a bit off in any one of several ways, the lens/reflector can't direct the light as designed. Typically, the LED emitters are much larger than the filament in a halogen bulb. The lens prisms (or shaped reflectors) can't work properly with that. The result is generally sub-optimal light spread, and excessive glare for oncoming traffic.

If you want LEDs that are really better, you'll need to pony up for self-contained 7" LED housings. Something like the the ones linked below. But good ones will be expensive, and you will still need to verify size for fitment inside the retractible 944 headlight buckets.

https://www.jwspeaker.com/products/led- ... evo-2-pro/

[Trouble]

I actually DID consider replacing the WHOLE light housing, But my 1987 Porsche 944 doesn’t have the simple aluminum frame that holds the light in the bucket, I’m sure I could come up with something, But I didn’t want to get into a modification that required changing the whole housing, I wanted to try the simplest option first before trying something that doesn’t work out…. And so far this doesn’t seem to be working out too well….

[Latitude48]

I have the JW Speaker Classic versions on both my 944s. The first set were $249 each from Summit Racing and the 2nd set I snatched off eBay were $166 each. I see from this link they now retail for $310.40 each (ugh):
https://www.jwspeaker.com/products/mode ... RgURVPmI7i