Bulb longevity

Baldytyke88

I was having 2 new headlamp bulbs fitted by our workshop apprentice.

He mentioned that they might have blown because they had been handled and a residue left on the bulbs.

I thought this was daft, although I have read similar, that might have been about Compact Fluorescent bulbs.

Why do bulbs blow/fuse?

Mildly_Miffed

An incandescent filament bulb is a very, VERY hot bit of wire in an inert gas. The gas varies - for most headlamps, it's halogen.

Why do they fail? The wire goes ping. Sometimes, that's simply age and use, sometimes it's vibration. If the voltage is low (perhaps poor connections), that can reduce the life.

Grease from fingerprints on the outside of the very hot bulb envelope can also cause premature failure through localised hotspots on the glass - which is what your apprentice was referring to. Never handle a halogen bulb directly - only by the metal base. If you HAVE to, wipe it carefully with a clean dry cloth before use.


"Xenon" is a misleading term - there's some over-hyped halogen-style incandescent bulbs that simply use xenon as the gas, but what it most often means is HID - high-intensity gas discharge lamps - which work totally differently and don't have a wire filament. Then there's LEDs now.

BlueonBlue

If the headlight internal reflectors are not as good as they should be ....are certain types of bulbs brighter so could help as a temporary solution ?

fatbelly

You can get longer life bulbs from most manufacturers

I have a couple of Osram Ultrlife atm as replacing them is a bit of a fiddle, best avoided.

WellKnownSid

BlueonBlue said:

If the headlight internal reflectors are not as good as they should be ....are certain types of bulbs brighter so could help as a temporary solution ?

Sounds like you'll blind oncoming traffic and fail an MoT - so a false economy.  Start looking on eBay or your local breakers for replacements...

Mildly_Miffed

BlueonBlue said:

If the headlight internal reflectors are not as good as they should be ....are certain types of bulbs brighter so could help as a temporary solution ?

It's not a temporary solution. It's a bodge that won't make much difference.

The proper fix is to replace the lamps.
If it's the plastic lenses have yellowed, then the "restoration kits" are good at removing the old UV coating which has failed.

Barkin

There are drop-in replacements such as Osram Night Breakers which claim to be 120/150/200% brighter than standard bulbs.

They're perfectly legal, so no MOT test issues and provided the lights are aligned properly they don't blind oncoming drivers.

I've a pair in my car, and they're a definite improvement on the standard H7 bulbs that they replaced.

There are 100w bulbs available, rather than the usual 55w ones, that use the same fitting, but they're usually designated "not for road use" or similar, and are not road-legal.

Goudy

There are plenty of reasons a normal halogen bulb blows.

Electricity causes the filament to glow, this produces the light but also lots heat and eventually the filament becomes brittle and breaks over time.

Obviously things like extreme temperature changes can cause issues.
More expensive bulbs are generally made with better glass, like quartz that handle extreme temp changes better.

The filaments are generally better in higher end bulbs, good quality tungsten tends to have a very high melting point, like 3,400°C or more and also has a very high resistance which is needed to cause the filament to heat up and glow.

Cheaper bulbs won't use as much expensive materials, so tend to last less and are prone to blowing earlier.

Bulbs are filled with gas. This gas is often a mix of gases like iodine and bromine and different mixes produce different shades of light, from yellowish to bright white to blueish.

What you were told is correct, grease from skin/fingers can cause hotpots on the glass and cause them to fail, but generally it's the filament that fails mainly due to age/use.
Always best to fit them without touching the glass part of the bulb.

shera12

It’s actually true for halogen bulbs oils from your fingers can create hot spots on the glass, which can make them fail quickly. So it’s best to handle them with a cloth or gloves. Other than that, bulbs usually blow because of voltage spikes, worn filaments, or poor connections.

facade

If you just want more light, at the expense of some bulb life fit Osram Night Breakers as Barkin suggests ("The star that burns the brightest burns for the shortest time" as they say virtually everywhere, but I was thinking of the original Bladerunner)

Don't bother with the 100W or 120W "Rally" bulbs (not for road use), as the thin wires in your car can't carry the current and they actually end up dimmer! (unless you re-wire the headlights)

I drove my old car for over 10 years with what seemed like two candles in goldfish bowls on the front, only the other day, 7 years after I sold it did it occur to me that the previous owner might have fitted "Rally" bulbs....

Goudy

I recently fitted some Philips X-treme Vision Pro to the boys car.
They are expensive, very expensive in my book (but I didn't buy them).

They are pretty crisp for a halogen type bulb.
My car has LED's all around and the Philips not quite on par, but it's not far off.

We'll have to wait and see how long they last.

The worst headlights on any car I have owned where on the Alfa 916 Spiders and GTV's.
They were ok on lit streets where you don't notice, but as soon as you are out of town on unlit streets, you would be convinced both dipped beams are blown and you were on your sidelights only.
No uprated bulb at the time made a blind bit of difference.
The lume on my watch glows brighter!