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Help replacing driver and emitter for headlamp

  • desolder Top 10 Forum Poster Thursday, December 26, 2013 3:12 PM Reply
    OK no prob if you don't want to disassemble everything. I just wanted to double check that you are getting ~2A at the LED, which is what was reported by ledoman and janisb59. You can reasonably estimate the LED current by reading the battery current from a fully charged battery, then dividing by ~2.3. That factor comes from the battery voltage under load when fully charged (~8.1V), divided by the LED voltage (~3.2V @ 2A), then multiplied by 0.9 to account for driver efficiency (typically ~90%).

    Keep in mind that the max temp claim from Cree is for the "junction" temperature. The exterior of the LED (typically called the "case" of the device) is typically much lower than the "junction" temp, due to the "thermal resistance from junction to case". For the XML, that figure is 2.5C per watt. So at 10W, if the max junction temperature is 150C, then the max case temp is 125C. Since you are measuring 112C at the case, I would consider it close, but still OK.
    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

    Posts(7073) | Reviews | Tip post

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