There are lots of head light bulbs manufacturers and types, but I've seen some claim to be able to provide 50% more light. Well, if the voltage that gets to the light bulb is always the same, for more light, the light bulb must have less resistance and the current in consequence will be higher.

Question(s) :

Will this type of light bulbs damage any part of the wiring?

And will their life time be shorter than normal ones? (This might be a silly question)

  • 2
    I disagree with the for more light, the light bulb must have less resistance. It might just be more efficient at generating light.
    – Hennes
    Commented Aug 12, 2016 at 22:41

3 Answers 3


If the bulb in question is the same fitment as the original (is just a higher wattage or whatever), then it should cause no issues with the wiring. I believe the main differences can be linked back to what type of gas is used inside the bulb and what filament is used to produce the light. Some are going to be hotter than others, no doubt.

Usually, if you look on the back of a pack of bulbs (thinking of Sylvania bulbs), it will tell you how they differ from other bulbs of the same type made by them. Usually I've seen the ones which claim to be brighter show to last less time than OEM style bulbs, but the brightness far outshines the originals. Here is one of the Sylvania charts:

enter image description here

You can see on the left side in the product description how long they are supposed to last. That is a general idea and you'll have a different experience, but it'll let you know what you can expect.

  • Does Sylvania has something to do with OSRAM? Here I don't find Sylvania products, but find a lot of OSRAM.
    – Syphirint
    Commented Aug 12, 2016 at 15:40
  • 1
    I think OSRAM is Sylvania. I was just using that chart as an example, though. Commented Aug 12, 2016 at 15:49
  • 1
    OSRAM is definitely Sylvania (well, OSRAM bought the North American remains of Sylvania from gte in 1993) en.m.wikipedia.org/wiki/Osram_Sylvania @syphirint
    – Jason C
    Commented Aug 12, 2016 at 15:51
  • I would think it would be worth calculating the draw of the new bulbs before assuming they are ok (or at least it would be interesting to know of there is a general rule of thumb about headlight wiring that guarantees that "upgraded" bulbs won't blow a fuse or otherwise cause mayhem and sadness).
    – dlu
    Commented Aug 13, 2016 at 0:40
  • @dlu - not really. The wattage consumed by all of these bulbs is the same for a given socket type. The answer below about filament temperature and efficiency explains how the light output can be different without changing wattage. If the wattage was higher, you would violate DOT regulations, and risk fires - not something a reputable company would want to be associated with for headlight bulbs. Commented Aug 13, 2016 at 15:41

Here is an engineering type answer- with a given technology (don't compare halogen with non-halogen), the lamp brightness will have a strong inverse relationship with the life. The design trade-off of where to put the bulb on a curve is a compromise. Below is a nomograph of what it looks like when you change voltage on an incandescent bulb.

enter image description here

If you make a bulb that is brighter it's like sliding the vertical dotted line over on the horizontal axis. For 40% more lumens the current goes up only 15-20% but the life gets slashed to almost 1/3.

So you can make a bulb that will last a very long time (conspiracy theorists notwithstanding) but it will be very inefficient (lots of watts and not much light to show for it). And very red light, but that's another story- the color temperature is really what temperature the filament is at.

  • This graph is nice but it seems to be showing what happens when you supply a given lamp with a different voltage than it was rated for, but that's not the issue. The op is replacing lamps wth different lamps, the system voltage isn't changing.
    – Jason C
    Commented Aug 13, 2016 at 13:38
  • @JasonC Yes, indeed, that is what they are showing but in fact a brighter bulb is just one designed to operate further to the right on the curve, with a lower nominal voltage if you will, so the curves are a valid means of comparison- the physics doesn't change. Commented Aug 13, 2016 at 19:22
  • You are misreading this graph. All lamps, regardless of their wattage, brightness, or rated voltage, are at the center point of this graph when used as intended. This graph does not show that brighter lamps have different lifetimes, it shows that running lamps outside of their voltage spec affects their lifetime and brightness. This graph illustrates that every 12V lamp is at 100% rated voltage, 100% nominal parameter values when run at 12V, regardless of its designed brightness, and that is not related to the OP's question. :)
    – Jason C
    Commented Aug 13, 2016 at 20:09
  • @JasonC I think we'll have to agree to disagree on this one. The designers who write the specs for the bulb have a design choice and they can place the lamp anywhere on the graph (but not beyond). A photoflood bulb with a few hours life is way to the right with very blue light, high efficiency and brief life. A rough-service bulb for a trouble light is to the left of what would be used for an ordinary bulb and is redder and lasts longer but is less efficient. Maybe it's harder than I think to see this. Commented Aug 13, 2016 at 21:10
  • I see no need to press further after this comment, but I'll say it's not a matter of opinion. This graph simply doesn't show, and isn't intended to show, a causal relationship between brightness and lifetime. A dim 12V lamp and a bright 12V lamp are still at the same point on the graph if the supply voltage is 12V - they're at 100% rated voltage, which is what the X axis is labelled. It's like if you say "the flu causes headaches and the flu causes a runny nose", you can't use that statement to support a claim that headaches are associated with runny noses. :)
    – Jason C
    Commented Aug 13, 2016 at 21:19

:"Well, if the voltage that gets to the light bulb is always the same, for more light, the light bulb must have less resistance and the current in consequence will be higher."

This is an incorrect assumption - light bulb light output is dependent on the temperature of the filament - the hotter the filament, the higher the light output for a given power consumption.

That's why halogen bulbs give more light for the power consumption - their filaments run hotter than regular incandescent bulbs. A quick measure of this, in the Sylvania chart given by Paulster2, is the light temperature - a 3000K light temperature (typical of a lower power halogen) is 3000 degrees Kelvin (3000K), because that is the temperature of the filament while it is running. A classic incandescent bulb will be about 2300K at most; a higher output halogen perhaps 4100K.

As the filament temperature goes up, the percentage of the power input to the filament that is converted into light goes up (and the percent that becomes waste heat goes down).

However, a hotter burning filament also has a shorter life - you can see this in practical application if you look at the Sylvania chart, but also in the lightbulb aisle of your hardware store - there are 'long life' regular incandescent bulbs, that use the same, say, 100 W as other bulbs, but give less light (lower lumens), and have a lower light temperature (instead of 2300K, perhaps 1800K). They are much less efficient at producing light, but last much longer.

  • No. The temperature published on the box is the color temperature, not the filament temperature. Those numbers don't describe the filament temperature, they tell you what color the light is using an ideal black body radiator at the given temperature as the reference. It's true that the filament temperature may be in a similar range, but it's not the number printed on the box. Brightness / color depend on a few things, color temperature is just a standardized hue reference.
    – Jason C
    Commented Aug 13, 2016 at 20:29

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