Underwater torches/flashlights

[_Bella_]

OFF TOPIC, but I've had the problem Marek describes with a Pcm, but never my PCa's. I've had 2 PCa's for well over 5 years and at least 500 dives without them ever popping. I got two PCm's last year to try out and the first one popped on the first dive and the second popped on about the 25th dive. Neither of them was in use at the time, just in a BC pocket where you could actually hear a *pop*.

I've had several screw down lights which always seem like a bad idea in theory, but in reality I've never once flooded them underwater.

 

[Marek K]

OFF TOPIC, but I've had the problem Marek describes with a Pcm

Not too much off-topic... shows the relative pro's and con's of various locking and switch designs...

Your experience with the PCm vs. PCa is interesting... Looks like the light heads on the two are identical, and the locking mechanisms... I would have thought that six AA-cells in the PCa would give off that much more hydrogen gas than four in the PCm...

--Marek

 

[Charlie99]

Not too much off-topic... shows the relative pro's and con's of various locking and switch designs...

Your experience with the PCm vs. PCa is interesting... Looks like the light heads on the two are identical, and the locking mechanisms...

I've done a few hundred dives using NiMH in a couple of different PCa lights and have never noticed any pressure buildup at all. Maybe it's brand of batteries. Most dives were with Panasonic batteries, but also quite a few with some weird brand X1/Spike/Changzhou.

Or maybe it has to do with excess hydrogen from the charge cycle slowly offgassing into the torch after newly charged batteries are installed. I always wait a few hours for the batteries to cool. This also dissipates the excess H2 that is generated from fast charging and the even larger larger amounts of H2 that are generated when a battery is overcharged at a fast rate.

 

[Dive-aholic]

I'm convinced it's an over-pressure problem of some kind, and hydrogen build-up seems to be the most-likely culprit. Though from what you're saying, it may not be because of rechargeable batteries, but just any kind of batteries.

Hydrogen does build up in sealed flashlights. The PCa's instructions warn about hydrogen build-up from batteries of any kind; though the warning is because of combustion danger, not over-pressure.

My experiences are consistent with an over-pressure problem popping the light head off, or wanting to. First, the light head coming off in my BC pocket... OK, that could have been operator error, but I don't think so because of the other evidence... like the damage to the locking lugs, and the over-pressure *pop* I heard another time when opening the light up.

In any case, good as the light is, I still think the PCa's locking mechanism is a bad design.

--Marek

You make a good point about the pressure. I don't think it's user error. I wore my PCa clipped and bungied to my right shoulder harness, not in a pocket. Well, mine is ready to ebay. Anyone interested in a barely used PCa?