Ikelite PCm vs PCa, UK SL4, Princeton Surge

[illumiGeek]

NiMH battereis will not vent gas unless overcharged, or over-discharged. The problems described here are likely from poor cell charging; poor quality cells; or mis-matched cells.

If one or more batteries are weaker than the others it will run down first and if the light is still operating the power being pumped through them by the remaining cells will cause it to vent. New cells take several cycles to level off and performe at spec. Prior to that they will often give uneven performance. Old cells will also get mismatched if they are not properly charged or maintained.

The more batteries you use, the better the chance this will happen. Also, a small volume light will (obvioulsy) have more problems with the increased pressure.

It is best not to run NiMH batteries down. Once the light starts to dim, turn it off. Trying to run the light down to the point where it goes out is just asking for this kind of problem.

When charging NiMH batteries make sure you are using a good quality "Smart" charger that is designed for NiMH battereis. Using a NiCAD charger on NiMH batteries will mess them up. There are chargers that can test battery capacity and allow you to better match cells.

All that being said, however, I am quite surprised that this problem is happening on something like the PCa. Venting problems are usually only with high drain conditions (multi-amp draws). I wouldn't think the PCa would draw enough current to be problematic. This leads me to suspect poor quality cells as the culprit.

I used NiMH in my PCa almost exclusively (while I had it) and had no problems.

 

[alo100]

Do you feel any of them is over driven? Esp. the those bright ones?
I compared the output of most of them, the brightness are quite different, esp when I was trying them in a LDS (on land).

 

[Charlie99]

Apparent brightness at the LDS will be very much affected by both efficiency of the light and how narrowness the light beam. You can make a rough guess on level of overdrive by comparing the color of halogen bulbs. Overdriven and hotter generates a whiter/bluish light. Normal or underdriven is more yellow.

The PCa and PCM lights are efficient because they are overdriven. IIRC, the bulb is rated for 5.0V. The tradeoff is expected bulb life of a few 10's of hours.

As I noted back in my first posts to this thread almost two years ago, I LOVE MY PCA!

The only problems I've had is that, if left on in the air, the 7.2Watts in such a small package will heat up and melt the plastic lens. So far my count is 1 light with a lens completely melted through (now a dry land use only light); 1 that "domed out" a bit but which I still use, and 1 that still has a flat front lens.

After about 2 years, frequent use on about 150 daylight dives, and used for about 20 night dives, I've gone through 2 replacement bulbs total. Rather than taking a spare bulb with me onto boats, I just leave an extra light in my dive bag.

I continue to use NiMH AA cells without any problems. I am cautious with the latching mechanism and to keep from damaging the tabs I first pull back the latch, shove the lighthead down into place, and then latch it into place. To avoid excess hydrogen, I only use reasonably well matched cells and recharge the batteries after a few day dives, and after more than about 1 hour of use on night dives.

 

[alo100]

Yes, I have seen that the Ikelite PCa some time back, it is very bright and I like it, but I have also heard that a over driven light would result in a shorter bulb's life (i.e. shorter than the average life claimed by the manufacturer).

Has anyone experienced that for the Itkelite PCa?
Since a backup is esp. critical if your main is failed, isn't that we want to have a something which is hard to fail (imagining 2 lights black out conseqently), I have heard others talking about it here... what do you think?

 

[alo100]

Yes, I have seen that the Ikelite PCa some time back, it is very bright and I like it, but I have also heard that a over driven light would result in a shorter bulb's life (i.e. shorter than the average life claimed by the manufacturer).

Has anyone experienced that for the Itkelite PCa?
Since a backup is esp. critical if your main is failed, isn't that we want to have a something which is hard to fail (imagining 2 lights black out conseqently), I have heard others talking about it here... what do you think?

oops, I meant die out one after the other in sequence.
Anyway, it's bright.

 

[Charlie99]

Since a backup is esp. critical if your main is failed, isn't that we want to have a something which is hard to fail (imagining 2 lights black out conseqently), I have heard others talking about it here... what do you think?

Depends upon what you are doing with it. I wouldn't use the PCa as a backup light for a cave dive where my life might depend upon having a light. For that I'd use the relatively dim, underdriven 3 C cell lights like the Halcyon Scout.

OTOH, if you are doing open water dives, all that happens if both my primary and backup (actually more like 2nd primary) fail, is that I teminate the dive and go up with my buddy. Even if I'm solo, my dive computer has a backlight. Even lacking that, most nights, once your eyes have night adapted, you can see amazingly well with no light.

I also carry a tiny little 2 AAA 0.4Watt light by UK. Good for assembling gear on a dark shore or boat deck. Good for using as a less intrusive dive light once your eyes have night adapted. Also good as my backup light when I pass one of my PCa lights to an insta-buddy, as his backup to the one rental light that is common in resort areas.

Normal bulb life is around 1000 hours. My estimate, based both upon my replacement of two bulbs over the last 2 years and a few hundred hours of dive time, and also upon the V^17 typical bulb life derating curve is that the bulb life is probably 10 or 20 hours.

It's the right tradeoff for the type of diving I'm doing. You need to figure out if it is right for you.