Crummy headlights - Can't see, need upgrade
My old 2007 GMC has never had the best headlights. Driving from Lethbridge to Calgary last night I was really cussing them. Old original factory headlights and I cannot see worth a darn. They are...
Forum Discussion
Gdetrailer wrote:ktmrfs wrote:pianotuna wrote:
Bob,
Power varies by the square of the voltage.
12.6 x 12.6 = 158.76
11 x 11 = 121
121 / 158.76 = 22% less light.
even worse than that.
on incandescent lights, light output increases about 3.5% for a 1% increase in voltage. for a car that means a 0.12V increase in voltage will increase light output by about 3.5%. typical drop between the battery and bulb with factory wiring can easily be 0.5V-1V. getting that 0.5V back will make a big difference in light output. A 1V increase in voltage will give close to a 30% increase in brightness.
Likewise a 1V drop from nominal will drop light output to about 70% of nominal voltage output.
Downside is that a 5% overvoltage decreases bulb life by 50%, while a 5% undervoltage almost doubles life. That's why the super long life incandesent bulbs are usually listed for 130V operating voltage, run at 120V they last a long time.
Most car bulbs are designed for about 13.5V
Most car bulbs never see 13.5V and would be lucky to ever see 12V in their lifetime.
Bulbs like the Sylvania Silverstars are a LOWER VOLTAGE and higher wattage bulb and with that they come with many less hrs of life..
SEE here..
Silverstars and Xtravision are rated for 12.8V 55W and 65W respectively max wattage and have 850hrs and 250hrs life respectively.. Many folks have complained after they paid the outrageous price for those bulbs after not getting much life out of them (they didn't read the box).
Myself, I have just used the standard halogen bulbs with a relay kit and have never had any issues with shortened bulb life. 22 yrs of my hr commute and most of that commute fully in night time hrs I can only remember replacing a couple of bulbs over 3 vehicles and the combined mileage of those vehicles was around 400K miles of driving..
OP will not see much if any shortened life as long as they stay away from the lower voltage higher wattage bulbs and go with standard bulbs..
yes, most "standard" bulbs will have long life even with full battery voltage going to them and be much brighter than factory wiring.
I did try the xtravision with upgraded wiring. Yes they were brighter, but a pretty short life. But IMHO not enough brighter to justify the short life and higher cost.
Key point is that light output is highly dependent on voltage, not a linear or square law relationship, even stronger but bulb life is even a stronger relationship to voltage. No free lunch.
