Some time ago I had bought (from Performance Products when they were having a sale) a set of four 5" Hella E-code headlights to replace the USDOT sealed beams on my wife's SL. (I have always preferred the lighting on 4-lamp cars, and though the US SL headlights are notably uglier than the Euros, they do offer this advantage [to me].)
This week I finally got around to installing them, a year or so after purchase! The last several days I've been driving to work with a screwdriver in my pocket so that I could dial-in the alignment. (This is trickier than it sounds, and following the alignment directions in the box resulted in unsatisfactory results. Unsatisfactory being defined as worse than what I started with.)
These lamps use H4's for the High/Low, and H1's for the High-only. I must say that I am impressed, especially with the high-beam performance. And the sharp cutoff on low beam is nice too. I have found that both sets of lamps are required in order to get truly good lighting. The H4's have a nice low beam, and a widespread high beam that lights up the ditches too. The H1's don't do much to the sides, but really light up down the road. This is all significant because I had been contemplating putting in a set of Xenon HID capsules in the H4 lamps. Expensive, but if it improves my wife's safety... Anyway, when you do this, you lose the high beam of the H4, which as I have found is somewhat significant to the overall high-beam lighting pattern. So I doubt I'll be doing this. I would never consider doing this on a car that didn't have four headlamps, and now I guess I wouldn't do that either.
(Most lighting 'upgrades' seem to be focused on improving the low-beam performance. However, around here the high-beam performance on the rural parts of our drive are more concerning, largely because of deer. The ad. for the HID capsules glibly claimed that you would never miss the high beams because the low beams are so good. That, sirs, is Crap.)
One thing I did notice was that the H4's appear slightly yellower than the H1's. That got me checking voltage drop in the harness, and I found a rather disturbing 1.2 V drop on the high beams! (No significant difference between H1 and H4, and no significant drop in the ground side.) I ran a piece of 12 gauge house wire directly from the battery terminal under the hood (where the meter and battery charger were connected) to the post of the H1, and though the lights brightened visibly the voltage drop was still 0.6 V! So it was time to purchase some relays and heavy-gauge wire.
Here is the headlight wiring before the wiring upgrade. Notice that the H1 headlamp doesn't use the old socket, but has pigtails that plug into it. (Pay no attention to that blue wire behind the curtain!)
I tapped into the wiring at the alternator terminal block connection, using a fuse block from a 114/115 model Mercedes, courtesy of the junkyard. (The source wire doesn't go near the exhaust manifold, that is an optical illusion. Also, only one of the two headlight wires [left and right sides are separately fused for safety] is in place, and the fuses themselves and the cover are not installed.) The wires to the two headlights are 10 gauge wire. (If I had it to do over again, I'd look harder for black wire. That blue is just too bright.) This upgrade not only eliminates the excess voltage drop in the stock wimpy wiring, but looks authentic and allows me to use extra-strength bulbs. (The new Hella lights are glass and metal, and look like they could handle the extra heat.)
Here is the headlight wiring after the wiring upgrade. I used separate relays for high and low beams, four new relays in all. While I was at it, I upgraded the lamps to 100W/80W H4's and 100W H1's. Even after this, the measured voltage drop was only 0.3 V! Success. (If my source material is correct, lighting output varies with the 3.4'th power with voltage change around the rated operating point. Using 12 V and 12.9 V this represents a 28% increase in lumens. Sadly, bulb life reportedly varies similarly but with the –16'th power, which means that the bulbs will only last 1/3 as long as with the original wiring.) The new lamps are very nice. We refer to them as "Lasers" (complete with Dr. Evil finger-quoting and accent), and we like them very much.
They draw about 30 A on high beam, which is pushing things a bit. But so far I've seen no problem with the charging system of the car.
Originally I had thought to do this upgrade to my wife's SL, and put Euro headlamps on mine. But now I am not so sure. Perhaps both cars will get this! The lamp-out warning module of my SL would need modification, though. Her older SL doesn't have this problem.
Some time after the headlight upgrade we had a heavy fog. The new lamps were very bright, and threw a lot of backscatter at you even when on low beams. So I tried driving with just the fog lamps on. (I had already rewired the car to separate the fog lamp function from low beams, and I had installed a rear fog lamp while I was at it.)
While the fog lamps had a noticably superior pattern (in fog) to the low beams, they were just so feeble that I could still see better with the low beams on, though the backscatter was very annoying. I had long noticed that the fog lamps were weak, and had concluded that, while never strong to begin with, their problem was partly due to damaged reflectors and lenses.
Factory replacements are expensive, and most aftermarket replacements are cheap and/or plastic. So I decided to try "Laser"-ing these too since the factory Hella lamps are glass and metal and look like they could handle the extra heat. I put 100W H3's in there, and ran new wire up to the headlight shells where the new relays are. I used 14-4 trailer wiring, which is a nice rubberized cable with four wires in it. I paralleled two of them for the new 12 V feed to the lamps, and ran one ground to the new lamps. (I'm continuing to utilize the original ground wire also.) The remaining wire feeds the relay coil input from the original fog lamp wire. I added a new relay on each side (not photographed) to drive the fog lights. As you can imagine, it's getting kind of tight inside that headlight shell.
I mentioned earlier that the high beam headlights now draw 30 A. The new fog lamps would draw another 15+ A, which is really pushing the alternator if they were all to be on at once. Probably too far. Also, because of the rewired fog circuit, they could all be on at once. So I did an unusual thing. Instead of grounding the other side of the fog relay coil like normal, I ran it to the filament connection of the high-beam relay. (This would have been completely unnecessary had the high-beam relays I used had 87a NC contacts from which to draw fog light power. My schematic [below] shows such contacts, but the relays I used don't have them, nor do most such.) This way, when the high beams are on the fog relay is off because its virtual ground is removed. (This is even better than the factory's original and USA configurations, the latter which required the low beams to be on to get the fog lights. [This was a cheap-o conversion to comply with the then-current USDOT regulation that stated that no more than four headlamps could be lit at a time on a vehicle: they complied by tying fogs to the lows thus preventing them from being on with the highs, which is good, but also preventing them from being on alone, which is bad.] Now they can be on alone, but not with the highs. They now not only comply with that USDOT regulation, but they also don't waste power [or their life] when the highs are on.) The only odd thing is that if you lose both high beam filaments on a side you'll also lose the fog lamp on that side because you lose the relay's virtual ground. I'm not worried about this. Here is a schematic in Illustrator, PDF, and GIF formats.
The lack of fog lights on with high beams is insignificant. My tests showed that you could barely tell the difference between fog lights on or off with the high beams on.
So how do the new fog lights work? Well, it hasn't been foggy yet. But they are noticably brighter than they were, and I have high hopes that it was all worth the effort. Did I mention that I had fused the left and right sides separately for safety? Well, it's a good thing I did. I had pinched a wire in the driver's side fog lamp, and a couple of miles down the road (in the dark) the fuse blew. But I still had half the lights. Two fuses is not as good as five (the factory configuration), but it's probably good enough.
