Xenon HID Lamp Lumen Degradation Over Time

What is a "reasonable" point in time to consider replacement of HID (D2S, in this case) bulbs, due to diminished output?

Edit: Changing of the bulbs resulted in a visually noticeable increase in intensity. It also seems to have restored the perception of a sharp cutoff.


I haven't been able to find information on how output of Xenon HID bulbs diminish over time for small bulbs (compared to, for example, stage lighting, or metal-halide lighting), except from sources intent on selling LED replacements in various markets.


I would guess that there is a reduction in output given that there are metal electrodes operating at high temperatures that will "plate out" onto the envelope, perhaps significantly so.


The automotive lamp specs seem to only quote B3 and Tc, which I understand to be related to catastrophic failure (3% and 63% failure rates), not partially reduced luminosity. A Philips 85122C1 quotes B3/Tc of 1500/2500.


A rough guess at run time for low beams for me is 365 (days/year) * 5/7 (night-driving days/day) * 1 (hour/night-driving day) ~ 260 hours/year. With a 2006 Mini Cooper, that estimate (~3600 hours) puts me somewhere around or past the Tc for the bulbs. Even at half of that estimate, I'd be past the B3 spec.


Since I think that the illumination isn't as strong as it once was, I've already ordered a pair of Philips replacements (and am hoping that it isn't just low-level, bucket-lens fogging I now see after 14 years), but am curious as to if there is some less hand-wavy information on automotive HID lumen degradation.

I would replace between about 1000 and 1500 hours of actual use time, you should have about 85% output at 1000 hours and 75% at 1500 hours.
You're likely only getting about 50% of output lumens at 3000+ hours of run time.

By the time you notice a degradation in lumen maintenance, you've lost quite a bit of vision with them.

Also, don't forget that old arc-discharge capsules are harder on the ballasts, because they require more current than new ones to strike, and to maintain, the arc.

My car manual says my HID lamps are not user replaceable and thus I should have them replaced by the authorized dealer. Is it possible that I change them myself?

Physically, yes, you could change them yourself. I have been told (but have not confirmed) that in Germany there are laws requiring that HID headlamps be serviced only by qualified personnel, though I'm not sure exactly how they would catch you if you change the bulbs yourself.

Regarding DIY replacement, I'd offer that on one of my cars, burner replacement requires removing wheel and removing fender inner liner to access the headlight unit. I can't even see the back of the headlight from under the hood. OTOH I have another car where the entire headlight unit can be pulled forward and out with a simple turn of the unlock catch. So, "DIY" is relative.

On Hella's German site, they provide professionals with two pdf's containing 100 pages (in awfully low resolution) of advice on "How to change a light bulb" on specific car models, but do not mention any legal issues for DIY'ers.
https://www.hella.com/techworld/de/Technik/Beleuchtung/Abblendlicht-und-Xenon-Lampe-wechseln-837/
Mercedes-Benz also target their lengthy HID safety precautions at professionals only, but without mentioning any German law.
https://www.motor-talk.de/forum/aktion/Attachment.html?attachmentId=731546
Those laws are likely directed at protecting commercial workers by requiring qualification before allowing them to deal with HV or HID. (The boss isn't supposed to tell his parts salesman to help a customer with installation of a pair of overpriced HID capsules.) A DIY'er is mainly obliged to properly dispose of the pressurized, toxic HID capsule. Even weekly general disinterest periodicals dare publish instructions to their readers,
https://praxistipps.focus.de/xenon-brenner-wechseln-so-gehts_48982

Mr. LED said:

My car manual says my HID lamps are not user replaceable and thus I should have them replaced by the authorized dealer.

Click to expand...

Manuals for two of my cars also say to get them changed by a dealer/qualified service personnel, probably just a low-key bid to try to steer you to your friendly [car brand] dealer. However, on the LS430, it is quite the chore to replace certain bulbs.

One significant concern is that the high voltage associated with HID bulbs can be lethal. Should you decide to ignore the manufacturer's warnings, for whatever reasons you have, I would strongly suggest disconnection of the electrical system and ensuring that all components are properly discharged. (For that matter, 12 V can easily weld metal together and isn't "completely safe".)

If you do decide to go with a dealer, make sure you find out the labor charge as well. US$15 for an H7 and then a half-hour of labor to install ($50-75) could well be what they'd charge at a MINI/BMW dealer.

Mr. LED said:

My car manual says my HID lamps are not user replaceable and thus I should have them replaced by the authorized dealer. Is it possible that I change them myself?

Click to expand...

Wear very clean gloves when holding the bulb. If using bare hands, if you touch the glass envelope by accident, wash the glass portion using cotton swabs to remove oils that come off your hands. use either isopropyl or denatured or "everclear" to wash the glass.

As a follow up, the new bulbs arrived from PowerBulbs to California in under a calendar week.

Notable observations that might help others in identifying when their bulbs have degraded (based on a single sample and "non-scientific" observations). One bulb was replaced at first to be able to do a "direct comparison"




On installation, past the awkwardness of having the lamps pointing up to the sky on the Mini Cooper (2006, R53, Xenon headlamps), refitting the igniter to the D2S bulbs has a couple surprises that I didn't find documented elsewhere. There is a small, yellow-ish ring within the igniter that picks up the cross-axial pins on the bulb. Not only does it need to be carefully rotated into position, but it is coupled to the insertion of the wiring plug into the igniter. You can't attach the igniter to the bulb with the wiring attached. There is also a brown lead that attaches over a screw on the inner frame with a round, press-fit connector. If you dislodge it, a gentle squeeze with pliers may be needed to reattach it (long-nose pliers or hemostats helpful).

Edit: There is still the puzzling misalignment between the high and low beams in the impacted unit (H7 high beam depressed relative to D2S low beam). I'm hoping to resolve this as the replacement Xenon buckets aren't available alone, just as a full unit (bucket, igniter, ballast, bulbs, covers) for $523 each side. It was this cost that had me previously considering JW Speaker 8630 (5 3/4") in Grote pedestal mounts in an above-bumper mount.