Re: Driving/Fog Lights

[Nick Craft <ncc@scr.siemens.com>]

>>I added some individual relays to improve the voltage reaching the 
>>headlamps on my 1986
>>5000CS Turbo when I added some high wattage 9004 bulbs.  
>Good move, Now your light switch will last forever and you'll get a 
>whiter brighter light. NJT
>
>>My nice new high wattage bulbs started burning out only after
>> 3 -6 months of use so I went back to the standard bulbs wattage
>>55/65W. Even with the stock bulbs I still was replacing the bulbs every 
>>12-18 months.
>Hmmmmmm  Read below......
>
>>Most bulbs burn out when they are first turned on (cold) due to low bulb 
>>resistance and the fact that the inrush current is something like 5-10
>> times the normal operating current. 
>Well not exactly correct, The cold resistance is higher than the hot 
>resistance but only buy a few %.  Yes it's true that the inrush current 
>is higher than the operating current but this last's around 10 
>milliseconds.  With Q/H bulbs this has to happen in order to jump start 
>the Redeposit cycle.
>
... Stuff deleted
>Later!
>
>Eric Fletcher
>'87 5KCSTQIA2RSR2B
>
>STEADI RIC@aol.com
>
>
>

To shove in my $.02, seems to me that improving the wiring to the bulbs will
increase the operating voltage at the bulb, say from 11.5V to 12.25V for
example. I also seem to remember hearing that bulb lifetime decreases rapidly
(exponentially?) as operating voltage increases over some threshold value,
this would explain a sudden decrease in the bulb lifetime.

Nick Craft