Dive lights won't turn on under pressure

[roadsta]

Hello,
I have a couple of back up dive lights that on my past trip will not work once they are down below about 10 feet. They work just fine on land but once in the water, they don't work. Anyone have any ideas why? Thanks in advance!

 

[fmerkel]

What brand? What is the switch mechanism? Link?

 

[rsingler]

I had exactly the same problem. They were apparently well manufactured Chinese lights with bright beams and low cost.
If yours are like mine, the contact is made where a flat polished land on the body links up with a metallic disc in the cap. The problem seemed to be that both are machined well, and meet face to face. All seems well on surface, but at depth, I thought case compression caused the two faces to separate, yet screwing the handle tighter didn't do anything.
I struggled for months with it, but can't figure out the design flaw. I tried roughing up the lands. I tried tucking aluminum foil in the space.
My conclusion? It's something else I can't fix. Maybe the magnetic switch alluded to above...
I junked the lights and bought proper dive lights for 3x the cost. Problem solved.
My condolences.
As the saying goes, "If the price looks too good to be true, it probably is."

 

[scubadiver888]

I've not seen this issue with dive lights but I have seen it with cheap cameras. The camera was designed for snorkeling and not for below 15 feet. If you went below 15 feet, a spring in the camera wouldn't work due to the pressure. The moment you go above 15 feet the camera would start working again.

I suspect there is a spring in the light switch which wasn't designed for the pressure.

Have you tried turning the light on before you get in the water then seeing if it stayed on? If it still goes out you are out of luck.

Hopefully you didn't pay much for the dive lights. I bought some cheap dive lights from China. They worked okay for a few dives but then they flooded and stopped working. Cost me less than $10. So no huge loss. In the end, I bought dive lights for $150 and they have worked for years without problem.