Homemade underwater fishing light

[florida]

The idea is to attract phototrophic baitfish to the light at night. Baitfish will gather around the light in the thousands and predator fish will soon recognize the feeding opportunity. Can anyone foresee any problems this thing might manifest in actual use? Soldering bare stiff wire to stiff leads was hard.
It features a Pyres glass test tube
50W 12V halogen bulb
Vinyl tubing
20 gauge wire
bb’s
boat plug
I wonder how long it will run off my 12V 75 amp hour deep cycle battery?

Any Ideas?
Thanks

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[kchriste]

50W @ 12V = 4.2Amps
75Ah / 4.2A = 17.9 hours
Time is approximate and you don't really want to totally discharge your battery so cut the run time in half. Running a Lead Acid battery flat really shortens it's life. This assuming you didn't get finger grease on the halogen bulb which will shorten the bulb's life too.

 

[Boncuk]

50W @ 12V = 4.2Amps
75Ah / 4.2A = 17.9 hours
Time is approximate and you don't really want to totally discharge your battery so cut the run time in half. Running a Lead Acid battery flat really shortens it's life. This assuming you didn't get finger grease on the halogen bulb which will shorten the bulb's life too.

Don't worry about the running time of the lamp. The night is shorter than 18 hours.

 

[mneary]

The air is gonna get mighty toasty inside that tube. I wouldn't trust ordinary vinyl insulation on the wire. How hot can that black plug be before it starts smoking?

 

[Mr RB]

Yep that was my thought. I have a similar globe but 20W in a desk lamp. It has metal holder and tempered glass cover, and it gets OUCH hot. Even with circulating air. Now 50W in a little test tube with no air circulation sounds like trouble.

20W in that test tube would probably work. There's not that much difference in the light output (to human or fishy eyes).

 

[mneary]

I would be tempted to try a 3W LED. Might even be able to use a fluid coolant. (Distilled water?)

 

[Boncuk]

The OP's light has plenty of cooling fluid: ocean water.

 

[mneary]

The ocean will keep the outer envelope cool, but I wonder if the air inside will get warm enough to bother the other stuff. The sockets for these bulbs are normally made with ceramic.

 

[Boncuk]

Since the OP doesn't use the socket of the lamp, but has the wires soldered directly to the cable I wonder when the melting point is reached either for an interruption or a dead short.

Spot welding (or crimping) would probably do a better job.

Soldering tin consisting of 40% tin and 60% lead melts at 183 deg/C.

 

[florida]

I tested it out last night and it seemed to go well other than condensation. The glass test tube was barely warm to the touch. The only problem was that condensation builds up at the bottom of the test tube. I was thinking about using a syringe and valve to suck out all air and vapor. I wonder what this would do to condensation. Ideas and comments are greatly appreciated thanks for the help everyone

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[kchriste]

You could put a desiccant in the tube to absorb any moisture trapped in there.
Isn't fishing with a light illegal where you are? Just curious.

 

[tcmtech]

Just put pure distiled water inside the tube. Its non conductive and as long as the bulb is completely submerged it wont bother it one bit.

Some of my dive buddies have had their outer lens seals break while underwater and the bulbs are not affected one bit by being on while fully submerged. Its only when they are on and come in contact with the water that they break.

Turn them on while they are cold and submerged and they never have a problem dirty or not!

 

[Sceadwian]

Distilled water will dramatically decrease the amount of BBS you need s there's no air cavity to deal with, but if that disitilled water ever gets dirty bad things will happen.

 

[Boncuk]

Use one or two droplets of pure alcohol (spirit) to put on top to be distributed in the ballast.

Alcohol has affinity for water and will reduce condensed water in the glass tube.

To get it almost perfect create a weak vacuum in the tube and inject the alcohol.

Boncuk

 

[kolisson]

just one idea:

if you fill the tube with some transparent oil,
you have your cooling and you stopped the kondensation

regards klaus

 

[RCinFLA]

This is beginning to sound like one of thoses 'how many XXX does it take to screw in a light bulb' jokes.