Well, just got back from two weeks of diving at the Red Sea -- first chance to use my Ikelite PCa.
First of all, I only did one night dive, and rented a nice light from the dive operator for that. Only had the PCa along as a back-up, and didn't touch it on that dive.
Other than that, I used the light on several day dives to "poke around" in dark coral holes.
Wow... Very, very intense light for its size and weight. Very useful.
Considering the concerns regarding hydrogen discharge, I had still decided to risk it and used rechargeable NiMH AA cells because of the rated puny two-hour burn time in the PCa. I took a couple of compact chargers along, each of which charges four AA or AAA cells -- also used the chargers for camera batteries, kid's Game Boy, etc.
On the first dive when I used the PCa, I wanted to save wear and tear on the rotary switch o-ring and left it switched on a lot, even when not actively using it. Toward the end of the dive, I turned the light off, and put in into my BC pocket.
When getting ready to rinse my gear, I found that the light was open in the pocket. Batteries loose all over the place. Uh-oh.
It had apparently just opened after coming up on the beach, because the light wasn't flooded -- batteries were still dry, and there was only a little condensation-type moisture inside that I was able to rinse and dry immediately with no apparent bad consequences.
But why did it open? Well, upon closer inspection, both of the lugs on the light head into which the slide lock engages were slightly damaged -- raggedly beveled, where originally they had been perfectly square. See attached image below.
Considering that the safety button locks the slide lock into place, it sure looks like the light head popped off under pressure from inside, damaging the lugs in the process. Sounds exactly like what happened to Bob/NWGratefulDiver, except it happened to me after the dive.
On subsequent day dives, I didn't keep the light on for long periods of time; just turned it on and off as I needed it. And it stayed closed and tight. After one dive, though, I did notice that the bottom of the light head was canted farther away from the body than the top, at the slide lock. And when I opened the light, the light head came off with a *pop*.
I did find the "hidden" hydrogen absorber, I think; it's a small grey cylinder under the small spiral spring behind the bulb. It's still intact and in place.
This has got to be hydrogen gas build-up. Maybe it is worse with rechargeable batteries, after all.
I think the lessons learned for me are:
1. Using rechargeable batteries is OK for daytime use, as long as the light is turned on no longer than actually needed.
2. I would still probably use the PCa as a nighttime back-up light with rechargeable batteries; but only for shallow open-water dives close to shore, where I wouldn't need to have it on for a long period of time in case of primary light failure. I'd prefer having normal alkaline cells.
--Marek
