How to prevent Fenix tail cap rubber boot from bubbling out so you can tail stand

The new click Fenix lights have very thin rubber boot button.
The light is airtight so it can be submerged.
The air expands inside the flashlight when it gets hot.

Because of these three things, the tail cap can balloon out and prevent the light from tail standing.

To prevent this from happening, I recommend letting the light get warm on Turbo setting. Once the light warms up, unscrew the tail cap and press the rubber boot fully in and screw the light together while still pressing on the rubber boot. This will get rid of most of the air inside the light and when it cools off, it should form a slight vacuum.

Good idea!

You don't need to warm it up first. Just hold the switch all the way down while you tighten down the switch.

I personally just get out the Lear Jet, take it up to high altitude, and load my P2D with battery there.

When I land, the rubber tail cap is flat.

You've probably noticed same effect when you drink out of a plastic bottle at altitude, and when you land, the reduced air pressure within the bottle causes the bottle to squash.

adnj said:

You don't need to warm it up first. Just hold the switch all the way down while you tighten down the switch.

Click to expand...

Yes but I recommend it as stated above.

abvidledUK said:

I personally just get out the Lear Jet, take it up to high altitude, and load my P2D with battery there.

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That doesn't work in my Lear Jet. It has a pressurized cabin.

:lolsign:

Doesn't seem to work in my Learjet either, but then it's only 3 foot wingspan and I can't seem to get in it.

Anyway, something to try. Thanks Leslie.

NutSAK said:

That doesn't work in my Lear Jet. It has a pressurized cabin.

:lolsign:

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It's only partly pressurized, as per commercial airliners.

abvidledUK said:

It's only partly pressurized, as per commercial airliners.

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Of course. I just find it easier and more effective to hike up to about 14,000ft. every time I need to change the battery. It's good for the lungs too.

The tailcap of my Fenix has yet to blow up, and I sometimes leave it on for 30+ minutes. I don't even push the switch down when I tighten the cap.

I have my wife sit on it, then i tighten the cap. It sometimes flattens but the tailcap never blows up.

And if you have an old Ford that runs like crap, start it up and redline it for 10 minutes.

It just doesn't make economic/environmental sense to throw away energy like that.

My P2D only ran about 10 minutes on turbo anyway.

How about a pinhole in the cap? Unless you're diving, it would never get water inside.

EDIT: If the batteries are outgassing, including solvents, an initial slight vaccum will only help for so long. It works if you assume no additional gasses will enter the battery compartment, but I doubt it's the case.

EngrPaul said:

EDIT: If the batteries are outgassing, including solvents, an initial slight vaccum will only help for so long. It works if you assume no additional gasses will enter the battery compartment, but I doubt it's the case.

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No gassing problem, just initial pressure from screwing the cap on and heat buildup. Unless, somehow, the gas is escaping as the light cools down.

As far as the 'green' comment--my old Ford runs just fine, thank you.

Just use a hammer like I did. It will need a few smacks but it works a treat.

Why not just take a pin and poke a single hole in the rubber cap? It should let the gas out when it expands but it should still keep the water out if you drop it in a puddle because the rubber will reseal around such a tiny hole.

GrnXnham said:

Why not just take a pin and poke a single hole in the rubber cap? It should let the gas out when it expands but it should still keep the water out if you drop it in a puddle because the rubber will reseal around such a tiny hole.

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Well if you poked a hole in it, and submerged it deep enough, the water will find it's way thru the pin hole. The deeper you go, the more pressure.
Try putting a pin hole in a balloon, then fill it with a little water. It will soon start to drip out.

We need a lear jet group buy or passaround! :lolsign: My old Fenixes can tailstand with no problem, maybe just replace the rubber tailcaps with the spare old ones.

AlexGT

abvidledUK said:

I personally just get out the Lear Jet, take it up to high altitude, and load my P2D with battery there.

When I land, the rubber tail cap is flat.

Click to expand...

Only problem with this idea is when it really cools down then the rubber cap sucks in so far the light turns itself on in the middle of the night. :laughing:

Somehow I doubt anyone would take a clicky light diving more than once. Remember a reverse clicky would also be continuously depressed from the water pressure, except unlike a forward clicky it would always be off at depth...

Prick it with a fine Needle