An issue with UltraFire WF-502B XM-L2

[amrasel]

My flash light(UltraFire WF-502B XM-L2) started to output with less brightness than it's usual.
I dropped it from about 1.2 meters and it hits the street with it's head( check the photo), the part of the head - surrounded by the red line , is a little bit bended. There is no other visual damages.

That flash light has 5 predefined modes - hi/mid/low/strobe/s.o.s. and currently they work the way they should be, only the output is significantly lower.

I checked the battery with a voltmeter and it showed 4.08V , so most likely be the battery is OK. Is that test is enough to say that 18650 battery is ok or I should do something else?

If battery is fine I assume my next step is to test the bulb. May be some part that handles voltage control is damaged. Is there a reliable way to test the led emitter , driver or I should leave this and just take a spare part ?

 

[JackDD]

I can't see the LED or driver being damaged by such a drop....especially if the five modes are still working and the LED is sealed in epoxy or some such thing. Is the focus the same as it was before? Perhaps the reflector or lens was dislodged. Recharge the battery. Testing a battery without a load will always read higher than the actual voltage.

 

[bladesmith3]

have you checked to make sure that the driver did not come loose? also check where the wires are soldered to the led. it is common for there to be poor solder points.

 

[HotWire]

To be sure I'd charge the battery in the proper charger. Then read the information at http://www.candlepowerforums.com/vb/showthread.php?227518-LED-Troubleshooting-guide-(budget-lights) If that fails you could buy a new dropin and install it.

 

[downzero]

Check the ring inside the base that tightens in the tail switch. When it's loose, it creates resistance and prevents the full battery voltage from reaching the LED. Something like snap ring pliers or just a pair of needle nose pliers are necessary to tighten it. Remove the tailcap and look down in there; it's the ring all the way around.