...quality geek time with h1 & h4 halogen bulbs...

[jaudette3]

Question:
When we used previous generation halogen bulbs we used lower watt bulbs for low beams and higher watt bulbs for high beams which seems logical. Now, with the latest generation bulbs, such as the Tungsram MegaLite Ultra +120 55w H1 and the Vosla +19 H4 we use the same bulb for both low and high beams. Has anything changed or were we mistaken to begin with?

Answer from Daniel Stern, AC Automotive Lighting Consultant:
That's a common arrangement, but not a universal one. Think of the H1/H1 headlamps, whether they're Porsche-specific ones made by Bosch or Hella, or the Cibie Biodes.

The answer is that it's the optics of the lamp, not the wattage of the bulb, which determine what kind of beam it puts out. A high beam doesn't become a low beam by putting a lower-watt bulb in it. A low beam doesn't become a high beam by putting a higher-watt bulb in it. Often a lower-watt bulb is specified by the automaker for low beam, because the priority is on long bulb life, and lower-watt bulb designs tend to have longer life. For high beam, maximum output is the priority and lifespan isn't so important because high beams don't get used as much as low beams.

Also, there is no direct link between bulb wattage (amount of electric power in the back) and output (amount of light out the front). There are car bulbs with ratings of 55w (plus or minus a few watts) ranging from about 1,000 to 1,810 lumens rated output. The 9006 "55w" bulb puts out 1,000 lumens with a long life. The H2 "55w" bulb puts out 1,810 with a short life. That's why the "55w" low beam filament of a standard H4 puts out a nominal 1,000 lumens, while the "55w" filament of a standard H1 puts out a nominal 1,550 lumens.

Wattage figures so far in quotes because wattages are a little more difficult to compare than it might seen, because there are *nominal* wattages and *actual* wattages.

The "60/55w" rating of an H4 bulb (found on the bulb package and in the owner's manual) is a *nominal* rating at 12.0 volts. The regulation governing car headlamp bulbs in North America lists maximum ratings at 12.8 volts, while the regulation in Europe (used throughout the rest of the world) gives nominal 12.0v and maximum 13.2v wattage ratings. Because wattage increases with voltage, all of these numbers are different. Here are all of the specs on the H4 bulb (called HB2/9003 in the US regulation):

Rest-of-world regulation says:
• 60/55w at 12.0v, nominal wattage
• 75/68w at 13.2v, maximum wattage

US regulation says:
• 72/65w at 12.8v, maximum wattage

This is not three different bulbs, it is the permissible specifications of _one_ kind of bulb at three different voltages.

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So there you have it.

Best,
John

[teenchy]

Interesting info, John.

I had Daniel put together a harness with relay for my H1s back in the early 2010s, long before I'd heard of Kroon or YnZ. I also bought 100w high and 55w low Narva bulbs from him as well. Is that still a setup you two recommend? I don't drive a lot at night but I do turn on my lights during the day if I'm driving in shady areas (little green car blends in with foliage easier than you'd think), hence I don't anticipate burning out a bulb anytime soon. But you never know.

[jaudette3]

You can go with the same power for both high and low as long as you adjust them properly.

Daniel is a very interesting man. His credentials are a yard long and I doubt that anyone in the world knows more than he does when it comes to automotive lighting. He relentlessly bases everything on science which is an oasis in the sea of hyperbolic lighting marketing. It just churns nonsense. Which can be more harmful than hype in other areas given that lighting is in essence a safety device.

We've had a relationship for many years although I have never met him in person. He provides me with unlimited expert counseling pro bono. He says that he likes to support folks who are trying to do something positive for the world and (blush) he puts me in that category. But he lives up to his name - he is a stern master. I've pulled products more than once after listing them without obtaining his approval. I'm very grateful for Mr. Stern. He is the heart of Audette Collection.