Silly WF-502B upgrade

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EdCo
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Silly WF-502B upgrade

I had a couple of old WF-502Bs lying around, and decided to drop these (maybe even genuine) XHP50.2 modules in them: https://www.aliexpress.com/item/33057289416.html

Here's what the LED looks like - seems pretty close to pics I've seen of genuine 3V XHP50.2s online:

They're bright, but, well, you know the drill. So I opened one up and soldered a trio of wires into it:

Here's how they compare (mod on the left):

A noticeable, if not astounding difference, and possibly as much to do with solder making better contact than steel when pressed against steel/aluminium. Will I bother to do the other one? Maybe - I'll wait to see if a glob of poorly adhered solder falls off and catastrophically shorts the first one.

EDIT - forgot power measurements:
With a multimeter in place of the tailcap, the modded one is drawing 2.4A while the un-modded one draws 2.2A. Tail-cap on, the modded one is running the LED at 2.9V.

Edited by: EdCo on 03/03/2021 - 22:46
Lightbringer
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Hey, I EDCed a ’502 forever, nice light. Pretty sure any XHP would be overkill in a drop-in for exactly those reasons: lousy thermal and electrical path.

Thermal, figured everybody knew, but electrical is a bit surprising. Those springs must bite to have such high resistance like that.

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EdCo
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Yep, overkill was the idea laughing

I got the 3-mode - it's quite useful at mid-brightness without getting too warm, and fine at full-brightness for a couple of minutes.

I dabbed some solder on the ends of the springs in the other WF-502B, and it hasn't helped much, so the issue is definitely resistance within the springs, not how well they make contact.

Lightbringer
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Yeh, that’s why whenever I can get away with it, I replace at least the driver spring with a brass nipple. 10pak from FT for about a buk or two…

Old-school ’502s had pretty good switches, but can’t say for any in recent years.

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