DIY Canister Light and Lighthead

[jtsmith]

Thought I would contribute my .02 on my Canister Light. I will try to get pictures up soon. Here is my current rig setup.

1st suggstion...buy the Airspeed press book...great ideas there. I will also skip most of the common sense parts, such as testing, letting epoxy dry, etc, etc.

Lighthead:
I used a 2 C-cell mag light and converted it to fit the MR bulbs. First thing I did was remove the rubber on/off switch and then rough up the edges around it with sandpaper. Next I filled it in the 2 part Epoxy. I did not reinforce it with anything, because as you'll see later, pressure is not an issue (trust me). Next I bought a brass male to male connector to fit standard icemaker water hose line (3/8 I think). I drilled out the endcap of the flashlight and then screwed it in. I used some 2P epoxy and stainless washers for a solid mount. I then installed about 3 feet of hose and ran 2 wires inside the hose coming out of the endcap. Leave yourself about 7 inches of wire hanging out the cap and then fill the endcap to the rim with hot glue. This will completely seal your wires and the tube on the end cap. After the gule cools, screw the endcap on and make sure the O-ring is in good shape. Now you need to go to your local glass shop and get a round piece of glass cut the same size as the lense. Thickness is personal preference and remember that pressure is not an issue. Now go and solder the wires to the light you want to use. I prefer the 75 watt Flood for tons of light and wide coverage. Heat is not an issue. Now after everything is ready to go....fill the entire light head with Mineral Oil.....yup mineral oil. You find it with the laxatives in the pharmacy section. Make sure and get as many bubbles out as possible. After you assemble...check to make sure none of the oil is leaking out anywhere. With the entire lighthead filled with oil you will not notice a loss of light, pressure will not affect your lighthead since it has no air in it, and heat is not a problem because the oil conducts it away.

The canister:
First buy the supplies...Go to the hardware store (Lowes for me) and buy a foot of 3 inch PVC, 2 - 3" end caps (flat and not round on the end), one 3" plug or test cap, one switch with silicone boot, one .5" wood dowel, and one male to male 3/8" icemaker hose connection. 1st, take the endcap and drill a hole for the switch and for the hose connection. Mount the switch and the hose connection. Run the existing hose and wires through the connection and clamp it down. Also, go ahead and put the switch boot on....I like to put a little loctite ultra black around the base for good measure. Go ahead and connect a few wires to your switch and make sure to give yourself plenty of wire to mess with. Take and cut about a 12" piece of PVC and glue it on the endcap. Make sure and run your wires through. Now fill the endcap with about an inch of hot glue making sure the switch is completey covered as well as the hose connection. You have now completely sealed the top of the canister. Make sure and install a switch guard!!!!

The Battery pack:
Go to www.batteryspace.com and buy 2 of the C size Nimh 10 pack for 22.99 with tabs.
Take 5 of the batteries and put them around the wood dowel and zip tie them together. Then make you a round divider out of wood or PVC and slide that on next. Then do another cluster of batteries. You will have 4 clusters of 5 batteries in the end. Make sure you soldered them together correctly. Now wire them up to the canister and slide them in.

Install the plug on the bottom of the canister and your done!

You should have 12 volts at 8 aH which give me a little over an hour with my 75 watt light.


This light is not very orthodox....but it works great and it is really cheap to build...batteries are the most costly. The reason I seal the lighthead and PVC canister is because the hose connections will leak....I've tried stress relievers and everything else...but with all of the flexing, the connection will start to leak. Another option would be to buy the expensive wire and grommets....but I am cutting corners for price here. Hot glue and water tubing are cheap man! The switch is also covered in glue which prevents it from failing from moisture. I know the boot could fail and destroy the switch....but I haven't had one fail yet. Oh yea....some salt will inevitably leak into the lighthead....so you may want to drain the oil every season and replace it because it will get a little cloudy.

I left out a lot of details that I assume common sense can provide. If you need more details please ask and I would be happy to provide! I will try to get some pictures up soon.

~JT
http://ecra.emeraldcoastboating.net

 

[canuckdiver]

interesting approach with the mineral oil.

I have heard of using it to pressure-compensate the electronics of ROV's, never thought of it in this application though.

 

[TheDarknessLord]

I got the airspeeds book, I'm waiting for it. I will let you know as soon I have it in my hands.... je je je

 

[dwood]

Once you've soldered these batteries together, what do you use to charge them as a unit?

 

[jtsmith]

This question was Private Messaged to me and I thought I would answer it here to benefit everyone:

Hope you dont mind me asking. I like your light idea. Couple questions. When you removed the rubber switch off the maglite, are you totally removing switch or just the cover(your actual swith is on the canister right?what kind of switch,rating,on canister).Does the maglite come with a plastic lens? Is that why you need to get a piece of glass cut? When you glue the cap are you filling in the brass male adapter aslo?On the light,are you using the existing reflector or are you buying the 75watt bulb with reflector?On the canister what is the plug or test cap for?How do you install the endcap so it can be removed for charging? Every time you charge do you have to refill the canister?Thank you in advance for your help.
Chace Cooper
​

I completely gut the maglite including the rubber grommit that covers the button. Make sure you seal it up with epoxy afterwards. The switch I use is a standard switch that you get in the electrical section of lowes, right by the switch grommits. Mine was rated 120V @ 15 amps which is more than sufficient.
When I fill the lighthead end cap I am also filling the brass adapter. So make sure your wire is already through it. I just did this in case the tubing holding the wire gets torn or frayed so it won't readily let salt water in. I have had a hole in my hose before and that oil will readily flow out letting the salt in.
The 75 or 50 watt bulbs have a reflector already. Like I said before, I completely gut the mag lite (except for O rings).
The end cap for the canister is held on by a hose clamp. To charge it I just put the whole canister upside down in a vise and remove the end cap. I then suck out any water that leaked in and pull the charging wire out and charge away.


Notes I learned from this year:
I found that if you make a cut out a piece of plastic the exact size of the canister and insert that into the bottom it will trap the water bubbles there even when you turn the canister upside down for charging. This makes it easy to remove them with a syringe.
Also, do not use electrical tape to hold your batteries together on the dowel. The oil will dissolve the adhesive and make a big mess. This year I am using zip ties.
I also had some leaks around my glass lense (it wasn't perfect round) and decided to use two regular maglite lenses stacked together. This works great and I would recommend it instead of having a glass one cut.

After 29 night dives this year the only thing that had to be fixed on the light was the charging wires. They were exposed to the salt water bubbles and corroded. Now I use the cut out explained above and I anticipate no other problems!

 

[Coop]

Well, here goes! Thank you for your help.
Coop

 

[unfix8r]

I think all would benefit from Padipro's MSN group, dive lights. The pictures are clearer, with directions and suppliers of equipment. I was advised to cut down the maglight and not fill it with oil, but kept the concept of using pipe fittings to seal the lighthead on mine. I've only posted three photos on Padipros group, but the light is becoming a reality.

Next on the list is to find a good way to attach the light to my hand so I can have two hands free, which was my point all along for this project. Enjoy!

 

[jtsmith]

Your going to have problems not using oil....the first thing that will happen is your wires will melt from the heat, even using a ceramic socket. 75 watts bulbs are incredibly hot. The next thing is the risk of leaking. I personally could not get my lighthead to not leak. All it takes is one flood to ruin a whole lotta work.

Let us know how it turns out.

 

[Padipro]

Your going to have problems not using oil....the first thing that will happen is your wires will melt from the heat, even using a ceramic socket. 75 watts bulbs are incredibly hot. The next thing is the risk of leaking. I personally could not get my lighthead to not leak. All it takes is one flood to ruin a whole lotta work.

Let us know how it turns out.

I don't know why everyone thinks they're going to have so much trouble with the heat from the bulbs. No other dive light on the market, including Dive Rite, AUL, OMS or Halcyon use any kind of oil in their halogen lights and all of their light heads are aluminum with either MR-16 or MR-11 bulbs. I've been using my 50 watt halogen light without oil for the last year and never melted anything. I DID try the oil trick though and had nothing but a royal mess to clean up after the dive. Even if you're using the solid PVC jacket wiring the oil is going to wick it's way down the wiring to the canister and on to the battery. I'm still getting oil, 4 months later, from the wiring after having cleaned everything.

If you convert the Mag-Lite properly and ensure that everything is sealed well prior to actually using the light on the first dive, everything should work just fine. And even if you do flood the light head it will do nothing but ruin the socket and the bulb. The light will function just fine even if it is flooded. I flooded my light head several times when I was testing out the concept of using the converted Mag-Lite and other then having to replace the bulb and socket after I got home the light worked just fine during the entire dive even though it was flooded.

One thing you need to make sure of is that you deepen the grove in the reflector housing enough to accomidate the added O-ring and that the O-ring isn't made of a hard rubber. I made this mistake when I first built my light and the pressure during the dive would crack the edge of the bulb and allow water past the O-ring. I switched to a softer O-ring material and haven't flooded the light head again.

 

[Diver0001]

Thought I would contribute my .02 on my Canister Light. I will try to get pictures up soon. Here is my current rig setup.

JTSmith,

How much did this project cost you?

R..