I fitted some +80 Philips bulbs to my car about 8 months ago and one of them has already blown. Considering that the majority of this time was over the summer and therefore little headlight usage, i'm a little disappointed.
Is this the norm for plus bulbs?
Thanks
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Just your bad luck - the other one might last 10 years!
A bit like disk drives on the computer - MTBF(mean time between failure) - 40 years and yours could blow tomorrow
Buy another and keep your fingers crossed
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Every time I've tried different bulbs in the car or bikes they have blown in a short time.
I'm back to the original bulbs now and 10 years/80,000 miles on the bike and they are still lit - and that's with dipped beams all the time.
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Did you ensure you left no fingerprints on the glass of the bulb? The 80% bulbs must run hotter, so this may be critical.
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< Ulla>
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Yes,
I made sure no prints on the bulbs when replacing them. I just thought that 8 months is not a long time but it might just be the luck if the draw on that one.
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Its not a long time, as a buyer I would be annoyed it it was anything under 4 years.
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< Ulla>
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One other thing I have though of, this is the first car I have ever had with Auto headlights (an S-Max), could that make any difference?
My last car, a BMW 320, was still on all it's original bulbs after 3 years and 119k miles.
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Complain to Philips Lighting (auto) sales department
0800 7445 4775
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< Ulla>
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Excellent customer service. They agree 8 months is too short a lifetime and will replace both bulbs. I just have to dig the bulb out of my bin as proof that I had a Philips bulb in the car in the first place.
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Did you ensure you left no fingerprints on the glass of the bulb?
Why does the odd fingerprint on a bulb make it blow early? I can see that it might reduce light output a fraction, when "burnt on", but...? Anyone?
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Probably causes differential bulb glass expansion/rates one would guess - the -'dirty' bit will tend to lose/gain heat at a different rate to the surrounding glass, so causing it to expand/contract at a different rate. More tendency to shatter, like a plate on a direct (localised) heat source.
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i 'think' that as the glass is so fine, if you put fingermarks on to it, the grease from your fingerprint creates a hotspot and the glass can overheat and fail where the fingerprint was. I'm sure more knowledgable people will confirm/correct as appropriate.
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The area around the fingerprint becomes a hot spot. The glass is there it keep the gas in and disipate the heat in the gas. The gas in the bulb is responsible for ensuring the filament does not burn out. If the gas is too hot it does not work as designed.
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< Ulla>
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The contamination from you fingerprints (grease and salt etc) on the glass alone will not do anything. It is only when the bulbs are on that the problems being. To begin with, at the high operating temperatures of a filament bulb (burns hotter by having a thinner wire and consquently must have a purer gas) the grease and the salt will react with the surface of the glass. This etches the surface and the surface only. Over time, and quite some time is required and again only really when the bulb is hot does the chemistry of the glass begin to change where the fingerprint has been etched into it. The etched fingerprint makes the situation worse because the light does not all pass through the glass, but is internally refracted thus causing further localized heating. The altered chemsitry of the glass results in small regions of the glass being more brittle than the bulk. It rarely becomes bad enough that the glass will crack at that point so whilst the filament has 'blown', the glass is still intact. It is possible, but in reality quite unlikely, that microscopic fissures form within the body of the glass that let air get into the bulb.
I think you have suffered from a duff bulb. Many fingerprints would not have shortened its life below the 8 months.
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>>If the gas is too hot it does not work as designed.<<
No!
The gas inside the bulb must be inert. At white-hot temperatures the tungsten filament is extremely sensitive to degradation, especially in the presence of air (oxygen and nitrogen). These react with the metal to form nitrides and oxides. These are brittle and are poor conductors of heat and electricity. Hence the filament blows. The key in the production of the bulbs is to inject the inert gas (helium, xenon, neon are all inert gasses) and keep it inert whilst the glass to metal seal is made.
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So does the inert gas disipate any heat anywhere?
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< Ulla>
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The glass doesn't dissipate the heat so to speak, it acts as an envelope of a high-pressure gas. When turned on and hot, the pressure of the gas inside the bulb increases to about 150psi and this is what helps keep the tungsten filament from evaporating. That's why the bulb is so thick and small, with curved top and bottom.
www.sylvania.com/ConsumerProducts/AutomotiveLighti...m
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Hi
I was looking at getting some 'brighter' bulbs for my car as the standard ones seem pretty poor.
I know that your experience has not been too good as one of your bulbs has blown but are these bulbs really as bright as philips would like us to believe?
Any info would be gratefully received.
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This thread may help:-
www.honestjohn.co.uk/forum/post/index.htm?v=e&t=57...5
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Improving quality and reliability gives an increasing "Mean Time Between Failures" but the earliest time can still be very low.
Having been involved with computers since the valve days (yes, really) through transistors and integrated circuits it's still true that the failure rate isn't evenly distributed over time - electric/electronic components may fail early as they're subject to repeated duty cycles but failure rates can drop in middle life only to increase again in "old age".
It's convenient to think that products have a predictable life span but few are like that, they're virtually all very variable.
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I must admit that I did find that they illuminated the road very well. Also, as Philips agree that 8 months isn't a reasonable lifespan they are replacing them for me.
All in all, I'd have to recommend them.
PS - My car has H7's and I think that if you have H1's the increase is even better.
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