DIY light cannister, ABS or PVC?

[Capnsnott]

I ended up going with PVC and some stronger than normal glue.
The ABS was too iffy for my personal trust.
thanks all. Good thread!
Greg

Now if I could only get the light head to stop leaking........

 

[miketsp]

Not sure. But is it a good idea charging a battery in a sealed container?
If memory serves than I'm pretty sure that when a battery is charged it
produces H2. Mixed with the little air in the container and possibly a spark
from the swith. And you just turned on a stick of dynamite.

Not sure about this, but it seems logical

Sorry for the late reply but this was a long holiday weekend here so we were out diving for the last 4 days.
Just a few comments:
With sealed batteries H2 generation is minimal.
I use a voltage regulated charger so overcharging does not happen.
There are no sparking sources inside my lamps as I use sealed reed relays operating MOSFET switches.
However, as you say, there may be a long term buildup of H2 so I have 2 tapped holes M3 in the backplate which I leave open when lamp is in storage. In use I just put screws in them with o-rings and washers as seals.

 

[PRL]

Thats great, Im glad that you found a way that you feel comfortable with.
I just wanted to make sure that anyone that wants to build a sealed container like yours takes all the safety precausions so they wont blow them selves up.
another safety would be to limit the amount of empty space (maby expanding foam or epoxy?)

 

[miketsp]

another safety would be to limit the amount of empty space (maby expanding foam or epoxy?)

Not a good idea. You need air circulation between the very hot lamp and the full surface area of the plastic. PVC is a poor conductor and over 90% of your 50W lamp energy is pure heat.
If you use an acrylic face plate (lens) you need it below 90C.
If you use a polycarbonate face plate you need it below105C.

Thats also one reason why I use an aluminium back plate. Helps significantly with heat transfer from inside to outside.

 

[bcsean]

Not a good idea. You need air circulation between the very hot lamp and the full surface area of the plastic. PVC is a poor conductor and over 90% of your 50W lamp energy is pure heat.
If you use an acrylic face plate (lens) you need it below 90C.
If you use a polycarbonate face plate you need it below105C.

Thats also one reason why I use an aluminium back plate. Helps significantly with heat transfer from inside to outside.

This is a canister light. The bulb is in the lighthead a few feet away on a cord. The only thing the canister houses is the batteries and the switch. I still don't think I'd use expanding foam to fill the air space though.

 

[daveg1]

I ended up going with PVC and some stronger than normal glue.
The ABS was too iffy for my personal trust.
thanks all. Good thread!
Greg

Now if I could only get the light head to stop leaking........

What is the problem with the light head?
I finaly finished my 2nd canister last night. I cant wait to get it in the water on a night dive next friday. Did a burn test and at 2 hrs I was still at 11.65 volts with a 50 Watt bulb. Now lets just hope for no leaks in the can. I have had the head out a couple of times on my old can with no leaks, so no problems there. But this will be the first time for all of it at 100'.