Lifespan of H4 bulbs

In 1998 I changed the stock headlights to the Hella H4 conversion with 55/100W PIAA H4 bulbs and then a short time later built a harness with (2) 30A relays to provide 13.6V to the headlights... and take the stress off the factory harness.
The only thing I did the installation was to coat the plugin connectors with dielectric grease and wipe the bulbs with alcohol to ensure no oil was on the glass (yes... I was wearing latex gloves when inserting bulbs).
This winter will be 10 years on the same bulbs with 13.6V.
Just trying to figure out why my bulbs are lasting so long when other XJ owners have problems with premature bulb burnout.

Anyone know how long the PIAA H4 bulbs usually last....?

You, my friend must live a charmed life!!! Over-driven bulbs like PIAAs typically have notoriously short lifespans. I got less than 6 months out of the last pair I ran!! :cheers:

My H4's without the harness last about 6 years, I've replaced them once so it may be 8 years, inside hella E codes. I cleaned the sockets with a burnishing tool and also used dielectric grease BUT I remove and clean the sockets yearly.
Those were stock 55/65w hellas, I have H4 silverstar motorcycle bulbs in there now, the ones they sell as singles.

I'm going to jinx myself on this one, the H4's that are in my CIBIE's on the TJ were replaced in 76 when I put them in my dodge van, since then they were in my 69 willys and now reside in my blue 97TJ....so the bulbs are 30 years old LOL those bulbs are older than most of the members here LOL...

RichP said:

I'm going to jinx myself on this one, the H4's that are in my CIBIE's on the TJ were replaced in 76 when I put them in my dodge van, since then they were in my 69 willys and now reside in my blue 97TJ....so the bulbs are 30 years old LOL those bulbs are older than most of the members here LOL...

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WOW.... This goes to prove that older equipment was made to last and most of the newer equipment is throw away & replace....

Reminds me of the story my mom told me about when she and my dad got married. Her mom gave her a used refrigerator purchased in 1949.
The refrigerator lasted until 1995 when my mom decided to get a new one that was more energy efficient with a defrost cycle....
She donated the refrigerator to GoodWill since still worked well, but the paint was starting to fade....