Posted by Deldolfan on January 16, 02 at 06:30:58:
In Reply to: Good info but the last paragraph needs a little polishing... posted by DanF on January 14, 02 at 23:13:10:
Close but no cigar. These types of bulbs operate at an extreme temperature which causes the filament to "off-gas" metal molecules which will recondense on the filament once the bulb is turned off. The reason the oil from your skin decreases bulb life is that when the bulb heats up this oil "boils" causing a cooler spot on the quartz. Consequently some of th metal will condense on this cool area instead of back onto the filament thus causing the filament to "wear" prematurely.
: : First, they should not cost that much. I paid about $18/ea for the 100watt highs for my 1996 Suburban. Like Philips over others, though WWS said the US made are coming up to speed.
: : OEM wiring routes the power from alternator/battery to fuse box, to ignition switch, to relay, then to headlamps. Plus theres not telling how many connectors there are inbetween all of that. Each connector, switch and relay add resistance to the run, which robs voltage. Plus they skimp on wire size, so there's additional voltage loss. Some day I'll get to wiring in my own home made harness, which should get 4-5 volts more than the stock harness. To prove, try this: connect same headlamp directly to alternator or batterie's postitive post. Completely different temp light. I like it even better than the latest HID's, as they have too much blue and not enough of the other color spectrum.
: : Automotive bulbs are designed for 14 volts. Anything less will reduce amount and intensity (brightness, color temp), but increase hours of life (MTBF, mean time between failure...an average of particular design).
: : Dan Stern does not recommend using 100watt on our plastic head lamps. Agree, but did it anyway. Will see how it does...though have had them in there for about 3 years. Don't drive with them on for extended periods, melts on coming traffics eye balls... :(
: : Guess you know to not touch the quartz (glass) of the bulb. Oils will cause the quartz to become porous and allow O2 inside which burns up the bulb.
: Sometimes it can be tough NOT to touch the glass when installing. No problem. Just wipe off good w/clean cloth/tissue w/some alchohol(no, not your beer!).
: Skin oil causing quartz to become permeable under heat? :-) What actually happens is skin oil under high heat can make for hot spots in the bulb. Thats what burns out a quartz/halogen.