Fenix L2D - Strange switch failure

On sunday I used my L2D, suddenly when I wanted to switch it on, the surface of the rubber wasn't flat anymore, but the switch bumped against the rubber and the whole thing was quite round.

I switched it on, it worked, off again, round rubber again. Then I screwed the tailcap off, the rubber flattened, I screwed it back on and it stayed flat. Half a dozen on/off and everything worked as it should.

What happened inside? Did something break so that this will happen again and eventually cause the switch to fail or is it "normal behaviour that happens sometimes"?

I haven't dissassembled the tailcap yet to have a look inside. The light is only a few months old.

Greets,

Henk

I'm not 100% sure if it's the same thing as you're describing, but I have noticed before that a Fenix tailcap can bulge out slightly sometimes due to the air pressure (I suppose) trapped inside.

Try this. Get the switch to how you described, bumped up. Then unscrew the head, and see if the rubber switch is then more flat. If so, I would assume it's just a little trapped air and nothing to worry about.

It is due to pressure and probably the pressure is due to some sort of gas from the batteries.

HKJ said:

It is due to pressure and probably the pressure is due to some sort of gas from the batteries.

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I didn't think of some sort of pressure inside the light, as the phenomenon appeared suddenly and I thought the bulge came from the switch, as I felt it under the rubber bulge.

I'll have an eye on it, as long as nothing is wrong with the switch, I'm fine...

I've had this with my l2d ... the tailcap blew up like a balloon and I couldn't even press it down.

It's your batteries venting I was told or from what I understand.

Are you running NiMh?

It's battery outgassing, not a switch problem.

If the OP is not convinced it was batteries outgassing, he could take the tail cap apart and visually inspect the switch assembly to be sure its not somehow falling apart.
I vote for the batteries venting though. It doesn't take much. Mine sometimes have trouble tail standing just from changing the battery and screwing the tail cap back on, so I depress the switch and hold while replacing the cap to keep the pressure from bulging the boot out.

It is definitely caused by battery venting. One of your batteries is weaker than the other and it is being reverse charged. This will never happen with good quality batteries with matched capacity.

jirik_cz said:

It is definitely caused by battery venting. One of your batteries is weaker than the other and it is being reverse charged. This will never happen with good quality batteries with matched capacity.

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OK, thanks for your answers, my switch seems to be OK...

About the quality of the batteries : I only use Panasonic Infinium NIMH which are charged with the special designed chargers for the Infinium. What's more, I numbered them to keep them together, so that the couple I put in the L2D has been charged together.

This becomes OT now, but I also observe strange behavior of the cells in my GPS. Sometimes it runs 15 hours with a couple, sometimes only 3 hours and mostly somewhere in between. They are charged immediately when they are weak and are probably stored only about 4 to 12 weeks until I use them. They should be capable of retaining 85% of their power over a year, so I only can explain their behavior with bad quality!