Ikelite PCm vs PCa, UK SL4, Princeton Surge

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ArizSig:
I think the reason they don't recommend NiMH is they give off a small amount of hydrogen gas as they discharge. In a water tight (therefore air tight) space, there is some concern that the hydrogen could build up enough to become explosive. It would most likely happen when switching the light on or off (spark arcing from one contact to another). Probably not a huge risk, but Ikelite has to protect themselves from the lawyers.

I suspect it's because the design of the light won't accommodate much pressure buildup inside the battery chamber, which will happen with rechargeable batteries.

My (ex)wife had a PCa that she used rechargeables in. On a trip to Sechelt (B.C.) we watched the light head literally "explode" off the light while at our safety stop, due to gas buildup. This is less likely to happen with a screw-on type light head.

... Bob (Grateful Diver)
 
I like Ikelite's Mini-C for a backup it is a bright small 4 C cell light that sell for around $20. I find the AA or AAA lights too small that said some of the 6 cell ones are better but the size is getting up to the Mini-C.
 
anyone had a chance to try the UK mini Q40 eLED yet?

Jim
 
I chose the PCa over the PCm as the on/off switch has a locking lever on it. I don't have to worry about it accidently coming on while in my BC pocket.

I have noticed this light has a pretty wide beam vs. a narrow one. I like that, but my wife doesn't like it on night dives as some spillover light gets into her eyes.

IMHO the PCa is about the brightest light for its size.
 
Anyone owning a Ikelite PCa,

From pictures, it doesn't look like there's anything on the housing to allow attaching it to a clip or somewhere outside on the BC. Is this true?

ch0ppersrule:
I chose the PCa over the PCm as the on/off switch has a locking lever on it. I don't have to worry about it accidently coming on while in my BC pocket.

I have noticed this light has a pretty wide beam vs. a narrow one. I like that, but my wife doesn't like it on night dives as some spillover light gets into her eyes.

IMHO the PCa is about the brightest light for its size.
 
ArizSig:
DiverDun:
I would like to use NiMH batteries but I know that Ikelite does not recommend them.
I think the reason they don't recommend NiMH is they give off a small amount of hydrogen gas as they discharge. In a water tight (therefore air tight) space, there is some concern that the hydrogen could build up enough to become explosive. It would most likely happen when switching the light on or off (spark arcing from one contact to another). Probably not a huge risk, but Ikelite has to protect themselves from the lawyers.
Old thread, I know...

I just bought an Ikelite PCa as a daytime light and night backup (still renting primary night lights for my occasional night dives). I'm very impressed by its size and relative light output, at least on land -- with the short battery life trade-off. But one reason I specifically got this model was that it uses AA batteries, and I thought I could use rechargable NiMH's with it.

I see the concern about hydrogen gas buildup with rechargeable batteries... and Bob/NWGratefulDiver posted that he had a light head on a PCa blow off, assumedly because of that.

But I don't see where Ikelite specifically recommends against rechargeable batteries. The battery plate inside the light does have ALKALINE AA CELLS molded into it. However, the only "recommendation" the instructions have is "for best performance, use EVEREADY ENERGIZER alkaline batteries"... but I don't consider that to be anything more than a commercial plug.

In fact, the instructions say, "The normal evolution of all batteries is emitting hydrogen gas. This gas must be absorbed or allowed to escape to prevent ignition of the entrapped hydrogen/air mixture. [...] A hydrogen absorber has been concealed inside this lite and should NOT be removed."

I think an absorber like this is pretty common in underwater lights. Anyone know where it is in the PCa?

So if all batteries give off hydrogen, why the big concern with rechargeables?

OBTW, I'm still not decided what kind of batteries I'm going to use for travel. I've got a good automatic compact charger that will do four AA cells at a time, but this light takes six -- so travel weight and recharge time are issues. On the other hand, I'm not sure what the cost of AA cells in Egypt is going to be. Or the cost or availability of C cells for my other backup light, for that matter -- because my charger won't do C cells.

--Marek
 
Marek K:
I see the concern about hydrogen gas buildup with rechargeable batteries... and Bob/NWGratefulDiver posted that he had a light head on a PCa blow off, assumedly because of that............

I think an absorber like this is pretty common in underwater lights. Anyone know where it is in the PCa?

So if all batteries give off hydrogen, why the big concern with rechargeables?

OBTW, I'm still not decided what kind of batteries I'm going to use for travel. I've got a good automatic compact charger that will do four AA cells at a time, but this light takes six -- so travel weight and recharge time are issues.
It's not clear to me whether NWGratefuldiver's light head blew off because of hydrogen gas, or because it had a leak and electrolysis generated a lot of gas.

I know that rechargeable cells will offgas significant amounts of H2 when overcharged, and also when reverse charged. A weak cell can be reverse charged while in use in the flashlight if the weak cell is completely discharged while the other cells have still have significant voltage. This could also happen by accidently using an already discharged cell with 5 freshly charged ones.

I'm not sure whether or not NiMH offgas more hydrogen than alkaline during normal use.

I've used NiMH in a PCa for about 10 night dives as the primary, and perhaps 150 daylight dives for looking into ledges and undercuts.

I bring 6 extra AA cells and a lightweight 4 cell charger on trips. That makes it easy to keep a set fully charged.

Somewhere in their literature, Ikelite says the gas absorbant is in the lighthead, and because of this that you should replace the lighthead if it gets flooded.

---------------

There are many other lights out there that use NiMH, NiCd, or lead-acid gel cels for power. I believe, but don't have any hard data to back it up, that the real danger is electrolysis in the event of flood.

As the guy falling from a 100 story building said as he passed the 10th floor, "So far, so good". NiMH has worked for me. YMMV.

Charlie
 
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
 
guymenton:
Anyone owning a Ikelite PCa,

From pictures, it doesn't look like there's anything on the housing to allow attaching it to a clip or somewhere outside on the BC. Is this true?

There is an attachment point that will take a wrist lanyard (provided) or that can be used to tie a snap link seen in pic link.

http://www.scubaboard.com/attachment.php?attachmentid=1467
 
I use a SL6 for primary, can't be used outside the water, it gets too hot!!!!!!!!

My backup is the SL4, this one can be used on land without any problems.

I attach 2 MiniQ40 to my mask strap for extra light.

All have worked great for yrs.

Avoid energisers for your lights, they ruined 2 SL4 a few yrs ago, now I use duracell.

I replace batteries as soon I detect some dimming in the output.
 
https://www.shearwater.com/products/peregrine/

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