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Bulb filaments are very likely to fail if they get too hot (overcharging?) or if they get shaken (out of balance wheels, unsupported rusty panels, rattling bonnet, bumper etc.). The airflow will produce large forces on the panels so a quick shake by hand may not show up a problem with a loose body part.
 

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Are you sure the filament had blown?
I had something similar and it was because the male contact on the bulb was going down the side of the female connector in the plug, it made a contact but not very good. In time it got hot and melted some of the plastic on the plug and lost the contact. Didn't find it till I checked the bulb with a multimeter.
 

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Running Halogen bulbs at reduced voltage shortens their life. Thus starting with the headlights on migh conceivably cause this. Bad connections due to dirty or corroded contacts will certainly cause it. This will also cause localised overheating which will worsen the problem by hastening more corrosion and the heat won't do the bulbs any good any way. And as has already been said, touching the bulbs with your fingers will leave greasy deposits on the glass. Which will cause hotspots on the glass envelope which will also lead to premature bulb failure.
Having said all that I fitted a pair of Osram bulbs with an alledgedly 30% extra light output (not that I noticed). One failed within 6 weeks and the other after about 3 months. The bog standard Lucas replacemants have been in for over a year now.
 

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I run with the headlights on all the time and I went through a spate of bulbs...why ?
they were bought from a very large car part retailer and they were cr*p
I replaced them with philps hi vision bulbs (something like that ) and had good "milage" out of them

recommended ( and stay away from H******S !!)
 

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Originally posted by Derek:
[qb]Having said all that I fitted a pair of Osram bulbs with an alledgedly 30% extra light output (not that I noticed). One failed within 6 weeks and the other after about 3 months. The bog standard Lucas replacemants have been in for over a year now. [/qb][/b]
I am not sure that we should draw any conclusions from this.

I have been running Philips VisionPlus (+50%) H4s in my Saab. The first set lasted between 1-2 years before one blew.

In the last four weeks I have had three headlamps blow - of which two were Philips Vision Plus and one was a "normal" H4. On the lamp that blew two bulbs one was normal, one was Philips VisionPlus.

So, there is not really any consistency to it

Yesterday, I installed two brand new Osram SilverStar (+50% illumination).

On the point of whether you notice any improvement over standard bulbs, I suggest this has a lot to do with the condition of the reflectors. The Vision Plus and SilverStars certainly do make a difference in illumination over normal bulbs for me
 

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I may be wrong, but I remember being advised several times that bulbs should be changed in parallel, ie both sides at the same time. As they get older they deteriorate and can cause an electrical imbalance. I have always changed mine in twos (often) keeping the 'good' one of the pair in the boot as a short term spare in case one blows.

On this topic, I also use philips vision plus and do notice a difference in both light quality, output and longevity. Have never tried the osrams as they are difficult to get over here, but certainly the philips are worth the €20.

Regards
 

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Originally posted by DaveJ:
[qb]I may be wrong, but I remember being advised several times that bulbs should be changed in parallel, ie both sides at the same time.  As they get older they deteriorate and can cause an electrical imbalance.  I have always changed mine in twos (often) keeping the 'good' one of the pair in the boot as a short term spare in case one blows. [/qb][/b]
You may be right.

The pair of Philips VisionPlus that lasted 1-2 years were installed at the same time.

The three bulbs that I have goine through in the last four weeks were replaced individually as opposed to replacing in parallel as was advised on the packet.

Perhaps replacing them one by one is a false economy?

Osram SilverStars were installed in parallel, both brand new, yesterday.
 

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Discussion Starter · #11 ·
Ill try replacing in pairs and see what happens. Also check connections etc.

Interesting old old / new bulbs. I had the bulb go on my wifes' Clio. (What a job to do!!!!!!! at least an hour)Within a week the other side had gone!

However replacing in a pair seems a pretty poor excuse for poor manufacture. did not have this problem years ago.(or is it rose tinted spectables)
 

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As the lamps are wired in parallel, I can see no reason electrically why replacing them individually should have any effect on life.

I too run headlights all the time and get at least 12 months from Philips Vision Plus.

The light output does deteriorate over time, and when a lamp fails at the end of it's nominal life expectancy, the output will be significantly lower- which is why it's a good idea to replace in pairs when one goes assuming you've had a year or so of life out of them.
 
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