HID Brightness Over Time.

jzchen

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Someone posed a question, and I was curious as well. Does an HID bulb start off brightest when new, or maybe starts off life dim then gets brighter with age, then dims as it gets old? Thanks in advance. (Can't figure out how to hit ENTER in the CPF app on Android. Sorry if everything is bunched up into one paragraph)!
 
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-Virgil-

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HID bulbs' output is highest when they're new, and it gradually/steadily drops off with accumulated hours of operation. A "3000 hour" lifetime is commonly cited for automotive HID bulbs...at that hour figure the bulb is lucky to be putting out 70% of its original output.
 

XeRay

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HID bulbs' output is highest when they're new, and it gradually/steadily drops off with accumulated hours of operation. A "3000 hour" lifetime is commonly cited for automotive HID bulbs...at that hour figure the bulb is lucky to be putting out 70% of its original output.

More likely 50% at 3000 hours from all the (Philips and GE) spec. sheet data I have. The bulbs should really be replaced (before failure) at 1500 to 2000 hours of use to keep them in the 70-75% output range.
Some users replace the bulbs after about 1000 hours to keep the output up around 85% or better.
 
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Alaric Darconville

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Not to mention that a worn arc-discharge capsule generates more work for ballast itself, so if you're using them beyond their useful lifespan (they turn on but have poor output) you're not doing your ballasts any favors.
 

XeRay

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Not to mention that a worn arc-discharge capsule generates more work for ballast itself, so if you're using them beyond their useful lifespan (they turn on but have poor output) you're not doing your ballasts any favors.

Absolutely a fact, hard on the ballast when the bulb is near end of life. The bulb arc Requires higher voltage (more thousands of DC volts) to the bulb arc itself, for the initial starting and closer to 100 VAC to maintain the arc in steady state as well, compared to 85 VAC for a newer bulb.
 
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