Canister Dive Light Construction Question

[jtsmith]

I have been checking out ideas for building an underwater light and I had a question for all of you guru's out there.

What keeps you from making a canister style light but not worrying about seals at all?

I am sure I am overlooking something here.....but here's my logic:

The gel cell itself is sealed so just solder your wires to the leads of the battery (carefully) and then coat them in sealant/rubber dip so they are water tight.

For charging...use a diode so you can have metal exposed underwater and the battery can't discharge.

For the light... use a 12 volt halogen and make sure and coat the leads to it as well. The water can touch the bulb as long as it's cold when you place it in the water.

That would leave no exposed wires other than the charging leads.

The only thing I can think of that needs to be sealed is the switch. And for that I could make a circuit with a relay and a reed switch and hermatically seal it all in a dip. THen all I need is a magnet for powering it up.

Did I miss something here?

 

[Aquamaniac]

No Problem except safety. In a sealed lead acid cell a resealing safety vent is provided to handle pressure buildup during abusive overcharges. Since the electrolyte is recycled, the water loss that requires routine maintenance or limits life is minimized.
Its also a replacement issue, how hard is it to replace the cells and lamps?

Other than that, you have some good points.

Dave

 

[DNAXdiver]

In the old days we used to make dive lights by soldering wires to a car or motorcycle sealed beam with one burnt out filiament and tarring the connection then hooking it up to a battery either that stayed on the boat or was "waterproofed" the same way. The problem is, there is usually a little air or gas space in a battery so it is not completely immune to pressure and eventually crushed or leaked. Patco still uses batteries that way abut I think they fill them up somehow so there's no air or gas inside.

You still got to make a waterproof container for the switch so why not put the batteries in it they last a lot longer that way. The Airpseed divelight book has a lot of good ideas for very simple cheap cannisters its almost easier to go that way than build one just for the switch.

jtsmith once bubbled... I have been checking out ideas for building an underwater light and I had a question for all of you guru's out there.

What keeps you from making a canister style light but not worrying about seals at all?

I am sure I am overlooking something here.....but here's my logic:

The gel cell itself is sealed so just solder your wires to the leads of the battery (carefully) and then coat them in sealant/rubber dip so they are water tight.

For charging...use a diode so you can have metal exposed underwater and the battery can't discharge.

For the light... use a 12 volt halogen and make sure and coat the leads to it as well. The water can touch the bulb as long as it's cold when you place it in the water.

That would leave no exposed wires other than the charging leads.

The only thing I can think of that needs to be sealed is the switch. And for that I could make a circuit with a relay and a reed switch and hermatically seal it all in a dip. THen all I need is a magnet for powering it up.

Did I miss something here?