Exploding PCa!

[jghflash]

Just got back from two weeks in Bonaire and I had the strangest thing happen. After 10 days of using NiMH rechargeable batteries in my wife's PCa (removed and recharged a couple of times), it exploded underwater in her hand. I figured she might have forgotten the switch lock or something so I chalked it up to getting overheated.

The next day I loaned her the PCa that I had been using for 10 days, with the same type of batteries, and it did exactly the same thing. I guess every time you open one up you take the chance of getting something in the o-ring, etc. and flooding but to have two of them blow up on consecutive days seemed beyond coincidence.

I was also using a PCm as a spotting light at night and I noticed it starting to get hot if I left it turned on for more than a minute or two (this was on day 11 or 12, but after the others had blown, so I was more aware then) . I use an Oly camera and housing so I'm kind of careful with cleaning and lightly greasing the o-ring. Anyone have any idea's? Thanks.

 

[Packhorse]

I was using some NiMH batterys in a pelican light (2x C). I was using it under the dash of a car (although I did find it 15 meters underwater). It got very hot and when I turned it off and opened it the metal bar that runns down its length had heated up and melted the case slightly. I still use the very same batterys in my PC lite with out issue. I also use the same batterys in my very expencive Fluke scope meter. Hmm maybe I shouldn't.

Edit: The pelican bulb has some pellets in it. I think these are for absorbing gas. I had a feeling this may have contributed in some way.

 

[Charlie99]

While I've had no problems using Panasonic NiMH AA batteries in 3 different PCa lights over a couple of hundred dives (other than leaving the light on topside and melting the acrylic lens), I have heard of others having problems -- both the "exploding light" problem and leaks. The PCa is an awesome light. Lots of light in a tiny package and in spite of hearing about problems I'll continue to use it.

I see three possibilities.

1. Hydrogen gas. NiMH batteries will offgas hydrogen when they are charged. You will also generate lots of hydrogen during use of the light if you run the batteries down so far that the voltage across the weakest cell is reversed. To avoid excess hydrogen I let the cells sit around for a while after charging and don't put them into the light until they are cool. I also stop using the light when I notice significant dimming (not reversing voltage across the weakest cell both avoids hydrogen generation, and also avoids the damage/loss of capacity that happens when you reverse charge the weakest cell).

2. Defective Latch. If you get seawater into a light, you can have electrolysis, generating both pressure from gases and also nasty corrosive liquids. A local dive shop owner tells me that a lot of people have had problems with wearing out the latch mechanism of the PCa. His best guess is that the little lip that holds things in place gets worn as people just pull on the release and let the spring tension pop the light head off. The light head is held in place by just the 1/8" or so lip at the end of the horseshoe shaped sliding catch. It looks like it would be pretty easy to round off either that piece or the mating surface on the lighthead. I always hold the light head in place until the latch is clear, thereby avoiding any wear on that little plastic lip.

3. Crud under the O-ring. I did have a few drops of water enter one of my lights. Upon removing the o-ring I found salt crystals underneath the o-ring. After a couple dozen of dives or so, I'll use a credit card to remove the o-ring, clean out the grooves an o-ring and very, very lightly grease it with a tiny touch of silicone grease.

Charlie Allen

 

[jghflash]

I sure like the PCa lights also. They are small enough to easily fit in the BC pocket and bright enough for poking around in the cracks and crevices during the day.

I was using the batteries for about 4-5 dives and then recharging them. I had read about the "let them cool and off-gas" issue so I was sensitive to that. Having a camera, I'm anal about the o-rings........the latch wear is sure a possibility I hadn't considered though.

Now I'm concerned about the 4C Princeton Tec LED light that I was using NiMH "C" cells in??? Hmmmm....what to do, what to do?

 

[fmerkel]

Just got back from two weeks in Bonaire....
I had been using for 10 days...Anyone have any idea's? Thanks.

Not sure about this but I know Bonaire uses 50Hz electricity with pretty wildly variable voltage. Unless you were hooked up to a KNOWN and GOOD transformer or had a charger that will handle 50-60Hz OK the charging might have done something weird to the batteries. We've had an 18W (incandescent) bulb explode after a battery charge there. This was with cooled batteries and not even in the water, just turned on to check function.

My charger hooked up to a transformer that's supposed to handle this sort of issue gets pretty damn hot down there, not usual performance for it. In the NW I've been using NiMH batteries in a 4D-cell light for years without issue. This is about 50 dive/year. That's the same light bulb that explode in Bonaire (UK400 converted to NiMH).

As someone else stated, running the batteries too far down produces H2, especially if there is a weak cell force into reversal. Any leak, even tiny, will short it out causing the batteries to run amok and possibly create the problem too.

Fritz

 

[jghflash]

Just a quick addition to the saga. I sent Ike a note to ask if they had ever seen or heard of this happening before with PCa's and NiMH batteries. He immediately replied and said they had not intended for those batteries to be used in the light (they are a slightly larger diameter than the "normal" AA batteries) but that if I would return the light to his attention he would replace it free of charge! I, of course, threw the exploded light away rather than pack it for the trip home........but THAT is customer service! I'll be buying a couple of more PCa's and sticking with the Duracell's next time!

 

[jghflash]

Here's the end of the story........Ike offered to replace both lights anyway (even though I didn't have the broke lights to return for his evaluation). Today I received two brand new PCa's in the mail! Now THAT's what I call Customer Service!