Eagletac P100A2 waterproof test: FAIL!

I had bought an eagletac P100A2.Very nice flashlight really happy with my purchase. Today i wanted to test 2xAA Batteries for their power,so i put them in Eagletac and started testing. Because of the heat, i decided to put the flashlight in a bottle with some water. THe flashlight is about 16cm, i put water about 15cm, only tailcap was outside of the water. At half an hour, i saw that the output was less than it was, so i took it out of the water to see what was going on.
The reason? There was water in the head! I was dissapointed, never expected that to happen. I stopped testing. I opened all threads, and clearly saw that the water got into the flashlight from the head, between the glass and the reflector.All other threads had the expected waterproofing.
So, what i have to do now?:mecry::sigh:

Sorry to hear that has happened, but as it was fresh water it should be fixable (salt water would have wrecked it).

Open up the head in whatever way seems easiest to let all the water out. Leave it all open and leave it in a warm dry place for at least 24 hours (without the batteries) to make sure it is thoroughly dried out. Using a hair-drier may help, but don't overheat it.

One important thing: do NOT touch the reflector with ANYTHING, not even a soft cloth, as this will risk damaging the fragile coating. You may be left with a slight water-smear on it, but that will be preferable to damage that would be caused by trying to remove it.

Disassemble the switch and head from the body. Leave these 3 parts in a dry box overnight if you have one. Or seal it in a box together with any moisture-absorbing agent that can be purchased for domestic use, like those for cloths cupboard. I heard this method is useful if your mobile phone is submerged too.

Out of curiosity, when the head was submerged, was it in a low setting? ie unscrewed slightly for low beam?

pV=nRT

Best to submerge and then turn on. If you submerge a light that has been on and up to a temperature much warmer than the liquid you submerse in, the quick decrease in temperature causes a decrease in pressure(inside light) and water can be sucked in through threads/O-rings.
G27

Really sad to hear that... I though the Eagletac was waterproof...

Zeruel said:

Disassemble the switch and head from the body. Leave these 3 parts in a dry box overnight if you have one. Or seal it in a box together with any moisture-absorbing agent that can be purchased for domestic use, like those for cloths cupboard. I heard this method is useful if your mobile phone is submerged too.

Out of curiosity, when the head was submerged, was it in a low setting? ie unscrewed slightly for low beam?

Click to expand...

Glock27 said:

pV=nRT

Best to submerge and then turn on. If you submerge a light that has been on and up to a temperature much warmer than the liquid you submerse in, the quick decrease in temperature causes a decrease in pressure(inside light) and water can be sucked in through threads/O-rings.
G27

Click to expand...

First of all thanks to all you guys that are interested to help me.Your suggestions are usefull but i firstly have to manage to dissasemble the head.
The flashlight was on high setting for about 10min, then because i didn't want the flashlight to get even hotter(i wanted to run it on high till the batteries were off,just to make a runtime test) i decided to drop it in a small plastic bottle. After 10min, i noticed a drop in output and i took it off the water to see what happened. I didn't dissasemble the switch, but it appeared to be ok, i might check it now.
But the real problem is dissasembling the head. It is really hard, like if it is glued, i didn't manage to do it and i doubt i will make it. Now inside of the head there are lots of scratches by trying to remove the head. I will try more and if i won't make it i will try to find another solution.
The theory about the temperature/pressure drop is very interesting, though, is it possible to happen due to that case?only 10min of high (not much heat) with very little pressure from water...
Also, another point, does the head, between the "teeth" and the glass, have an o-ring on yours? I think that mine hasn't(glass and host are really close,i think that they touch each other) and now i took of it notice, if i manage to disassemble it i will see for sure.

I already sent an email to the dealer to see what we can do, i am afraid to continue trying to open it, i might damage it.

The light is advertised as waterproof, so if it does not work because of the water, then someone will probably replace it (either the store you bought it from, or eagletac itself).

The temperature, effecting the inside gas pressure, inside the internal parts of the light will be much higher than external temperature.
There would be 2 separate zones of pressure in a light. While the head might not have a solid seal in relation to the body, the pressure in the head would rise or lower much quicker than the battery compartment. I would bet that the front o-ring or seal between glass & metal would be the weakest link on temperature drop.
G27

I don't think the temperature difference would cause water to be "sucked in" any more than it normally would while submerged in water. In order for water to be sucked in, you need the pressure inside the light to be lower than that of the water. Not only this, but this gradient has to be large enough to break the O-ring seal.

The fact that the head goes from warm to cold shouldn't effect the waterproof seal of the light. If you put a warm light in a bottle of water, the lowest the temperature can go is that of the surrounding water, which is what the light would reach if it was turned off. Since the head is hot, lets assume that the pressure inside the head is slightly higher than normal (while the light is off). This would result in a smaller pressure difference between the head and the water, not a larger one. You will not get more suction because of the hot head becoming cold. It is the difference between the outside pressure and the inside pressure that matters, not the rate at which the pressure inside lowers.
In fact, putting a hot light in water would probably result in less of a temperature gradient, since the air inside the head is at a slightly higher pressure than normal.

Since there is very little water pressure inside a water bottle, then there is even less likelihood of any serious pressure gradient occurring.
If the light is meant to be waterproof, then it should be waterproof whether it is warm or the same temperature as the water.
If it was a high output incan it might heat the air enough to cause too much pressure inside the head, but I doubt that an LED will do so. They really do not get all that hot, especially when submerged in water.

My guess is that the threads and O-rings were not lubricated enough, so they didn't completely seal. That could also explain why the head was hard to unscrew.

The laws of physics are very powerful. When you cool the hot head in water by dunking , the pressure in the head must drop. This is absolute. When the pressure plummets by the rapid cooling, an amount of water will be sucked in if there is the slightest problem with the front seal.
G27

Just to add that the flashlight when it was submerged(15cm only!) it was just hotter than the temperature of my hand,(32 C on measured by laser thermometer some days ago), so i guess about 36-40 C on the body of the flashlight. Water(i did not put water in the bottle, water was in there already) temperature was about 24 C, summer has almost come here in Greece.
Take a photo of the result:

Yes, the pressure inside the head will drop. However, it is not the difference between the initial pressure of the head and the final pressure of the head that matters, it is the difference in pressure between the water and head that matters.
If the light is on, the pressure inside the head of the light is slightly higher than normal. This results in positive pressure inside the head while it is in the air.
When you put it in the water, the pressure inside the head is lower than the water. While the light cools, the pressure inside the head will go down, resulting in a bigger pressure gradient.
However, this final pressure gradient is THE SAME, if not higher than the pressure gradient that the light would experience if it was submerged while turned off. In fact, I would think that the light being on would lessen the pressure gradient slightly.

You seem to be missing the fact that the light cannot become cooler than the surrounding water. If the light can retain its seal while turned off in the bottle of water, then the fact that it is on should not change that.

When you lower a light that is turned off into water, the inside of the head goes from being an area of high pressure to an area of low pressure. If the head has a slightly higher temperature, then this difference is not as big, and therefore the light is LESS likely to have the seal broken, not more.

It is possible that the "rapid temperature change" could cause the O-rings to shrink slightly, which could break the seal. However, the temperature difference is probably not enough to do this, especially if the O-rings are designed properly.
However, saying that the "rapid change in pressure" will cause the water to be sucked in because of the pressure change within the head is not true.

Guys, just to add a comment to your very interesting dialogue, i have done the same test again in the past with lots of flashlights(almost all of my collection) and even a cheap Ultrafire did not have that problem....

Mjolnir said:

<snip>
However, saying that the "rapid change in pressure" will cause the water to be sucked in because of the pressure change within the head is not true.

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You only think it is not true. You don't understand the physics of what really is going on. There is a restricted opening between the head assembly and battery compartment. Heat the head slowly and pressures in both zones are the same. Rapid cool the head by submersion and pressure in there could drop much more there until it equalized through the restriction.
I would be surprised if you wouldn't see a ~2 psi drop......which would be ~4 ft water column.

No offense, but that makes very little sense. First of all, LEDs do not produce all that much heat, so I seriously doubt the pressure in the head would be much higher than either that of the air around it, or of the air in the battery tube.
Second, you still don't seem to understand that it is the pressure gradient that matters, not how fast the head cools. There would be the greatest pressure difference between the head and the body when the light is on, in the air (which will result in maximum heat buildup). If the head is not sealed, then the pressure will equalize between these two zones. It is probably not a perfect seal, so some air could theoretically go through, if the pressure is high enough. but again, LEDs really do not get all that hot.

Remember the ideal gas law uses Kelvin, so we are only really looking at an increase of air temperature of maybe 10 K (up from about 298 if it is room temp. Since the OP states that it was in fact 40C, the change in pressure should be minimal). This would only raise the pressure slightly over the normal pressure inside the head. We are not talking about explosive decompression here. Any "equalization" between the head and the body would be minimal.
Even if the pressure does "equalize rapidly," as you say, how will this effect the seal at the front of the head (on the lens)? If the whole inside of the light is an open system, as you suggest, then it this equalization should not matter. The overall pressure relative to the outside should be the same. What you are sayign would only remotely make sense if the head was pressurized, but then became depressurized by some break between the head and the body. However, the head is either sealed off from the body (making it an open system), or it isn't (making it closed). If it is open the pressure will equalize basically instantaneously; if it is closed then there is no way that the pressure created by the LED will "blow open" the bottom of the head.
Either way, this "equalization" would not affect the front seal. Perhaps I still don't understand what you are saying, but from how I understand it, it seems incorrect. Perhaps another, more knowledgable member can verify which is correct.

2 psi is significant.
G27

I quit trying to open it. It is impossible. I will destroy it if i try more. It already has some "remarkable" signs of trying to dissasemble the head.

I'd try heating in oven ~140F until all visible water in head is gone or have a refrigeration shop pull a vacuum on the head overnight....unless, of course, you can send it back for a new one.
G27

Mjolnir said:

First of all, LEDs do not produce all that much heat,

Click to expand...

Say what?


Anyway, to the OP just contact the dealer. You should get a new one no problem as they're rated "Waterproof to IPX 8 Standard."