DIY Canister Light and Lighthead

[Tiny Bubbles]

Well, my little canister light project is starting to take shape... I may catch a little flak from this group for this, but I'm using a pair of LANTERN BATTERIES! Actually, they're 6v/5ah sealed lead acid replacements for lantern batteries. They're $9 each from zbattery.com.

Lantern batteries are a snug fit inside of a 3.25" ID pipe. They don't make 3.25" PVC, so I bored out 3" PVC pipe to 3.25", leaving a 1/8" thick wall. I cut it up into 3 short segments, and glued them inside of (3) 3" couplers (and one rounded end cap for the bottom). Now the wall thickness is a strong 3/8". The OD of the canister is 4". Total length including the lid is 11.5"

To make the lid, I bought some 1" thick acrylic from mcmaster-carr, and cut a 4"+ round out of it with a circle cutter in the drill press. Then I drilled 2 holes in it where the switch & cord would eventually go, and used those holes to bolt the acrylic to the lathe face plate. I turned the OD to match the canister OD, cut a shoulder to fit snug in the pipe coupler ID, cut an o-ring groove in the shoulder, bored out a recess for the switch, and sanded & polished the whole thing. Then drilled out the 2 holes to their final diameter & tapped the 1/2" pipe threads for the sealcon cord gland. There are 2 o-rings sealing the lid to the housing.

I'm using a 20A double-pole, double-throw switch. It can switch the batteries from series (12v/5ah) to parallel (6v/10ah).

The glue is drying right now and I've still got a ways to go before it's done, but I'll keep the group posted on how it turns out.

 

[Padipro]

Nice job. Sure makes things eaiser when you have the lathe. You're able to do much more intricate work. Keep us posted on the out come.

 

[in_cavediver]

I'm using a 20A double-pole, double-throw switch. It can switch the batteries from series (12v/5ah) to parallel (6v/10ah).

Your pics are a bit rough but it looks like a really nice job. One question though? Why the dual voltage configuartion on switch. I can't think of a reason to cut the voltage during a dive. I could on the surface with a different voltage lamp or lighthead but not underwater?

Mike

 

[Tiny Bubbles]

Your pics are a bit rough but it looks like a really nice job. One question though? Why the dual voltage configuartion on switch. I can't think of a reason to cut the voltage during a dive. I could on the surface with a different voltage lamp or lighthead but not underwater?

Mike

It's an attempt to save power when full brightness isn't needed, but keep the full intensity available at the flip of a switch. Our cars run their headlamps at 1/2 voltage for the daytime running lights, and they seem to work OK, so why not give it a try in a dive light? It also povides some redundancy in case a battery fails or if a battery terminal loses contact. I may change my mind about all of this after I get it in the water, but that's how these experiments go.

One nice thing about this switch is that the center-off position makes it easy to get a socket over the rubber boot to tighten it, without it rubbing the boot in the middle.

-tiny

 

[unfix8r]

It's funny when you look at everyone elses' lights.
I pretty well finished off my light last night while watching the Oscars. (pics to follow tomorrow) Can you believe Lord of the Rings? I thought that movie stunk!

Back to the light:

I wish in retrospect that I had recessed the top of the light for the switch like you did, Mr. Bubbles. It would eliminate the need for a switch guard, another piece that needs to be installed on mine.

The only problem I see with latern batteries is that you'll have to replace them, if I read that right, where they have the little spring contacts on the top? Why didn't you go rechargeable?

 

[unfix8r]

Oops! I read that they are SLA batteries. Disregard my last question!

 

[in_cavediver]

Well, I just got my light finished. Here's a picture of the 'short' canister. I made two interchangable canisters, a single and double 12V/7Ah pack. The pipe is 5" electrical conduit with a glued on machined PVC base. The top is machined acryllic. Its done except for attaching the strain reliefs and the switch guard.

Here's a link to the pix:
http://tools.ecn.purdue.edu/~loganm/hmdive/light.htm

Mike

 

[Padipro]

Dual light heads? Is this a video light? Looks good. I like the engraving in the top, nice touch. Can you post a few more pictures on the MSN site for others to see? Thanks.

 

[in_cavediver]

Dual light heads? Is this a video light? Looks good. I like the engraving in the top, nice touch. Can you post a few more pictures on the MSN site for others to see? Thanks.

No problem. The photo I posted was a quickie to say, HEY it's finally done and it came out working! I was plannig to add a lot more detail to the method of construction I used and drop it on my webpage. It shouldn't be much to add it the MSN group as well. I hope to get that done this weekend.

Oh, and yes it is a dual 75 watt MR16 video light. I have another just about done for a 35 watt MR11 can light. (For the fiance')

Mike

 

[Tiny Bubbles]

............The photo I posted was a quickie to say, HEY it's finally done and it came out working! .............................
Mike

You're way ahead of me. I've wasted lots of time on my PVC paint job. I want to paint the canister so it looks nice instead of looking like 4 PVC sewer-pipe couplers glued together, but I feel like I'm taking one step forward and two steps back every time I mess with it. I'll shoot some paint on it and notice one little thing wrong, and try to fix it, making it 10 times worse in the process, and have to sand it down and start all over again. I'm no painter. But I'll get it eventually.

I finished the maglite light head! (See attached image!) The o-rings finally came in from air-oil.com. So I got my 2-133 o-ring to put behind the glass rechargeable maglite lens. I did have to deepen the groove the same way padipro did. I cut my groove 0.147" deep -- Removing the bevel and then a little bit more. It could be cut a little shallower or deeper -- I haven't taken this light head to any great depths to test it yet so don't take that 0.147 spec as gospel.

My little harbor-freight 8x12 mini-lathe won't do 28 tpi threads, but instead of grinding all the threads off the head and then mushing the handle & head together in a big gob of epoxy like some of the other DIY maglite heads out there (no offense to anyone! -- Those guys invented the maglite canister light head!), I turned down the handle to be a slight interference fit with the threads on the head. And I added an o-ring groove just like on the original handle for good measure. Then I packed a little JB Weld into the threads on the head, and pressed the handle into it with my 30-ton press. (No respectable backyard garage in SE Michigan should be without a lathe & press). The JB Weld made a fine lubricant for pressing the two parts together... Until it dried! Like I always say, there's nothing stronger than a tight press-fit with a little JB Weld in there, too.

I did one burn & leak test on the batteries & light head. I submerged the light head in a bucket of water, with a solux 50w bulb in it, and connected it to a pair of the 6v5ah SLA lantern batteries in series (12v5ah). The bulb burned bright for 50 minutes, and then petered out for 10 more minutes but was still burning dim when I ended the test at 60 minutes. I measured voltage and amperage every 10 minutes, until 50 minutes passed & I measured every minute after that. It began at 11.5 volts, 3.99 amps. It steadily decreased for 40 minutes to 10.27 volts and 3.68 amps. At 50 minutes it started on a slippery slope with 8.2 volts and 3.36 amps. At 60 minutes it measured 3.94 volts and 2.21 amps and I ended the test. The batteries fell short of the advertised 5ah each because the current draw was more than the weak current draw they use to rate the batteries. But I was shooting for 45-60 minutes so they are adequate for my needs. I haven't done a full burn test with the 6v/10ah "dim" setting yet, but I did take one measurement with full batteries: 6.0v, 2.79 amps. This looks promising... I expect maybe 3 hours run time with light output comparable to a 20W bulb (but the full 50W is just a flip of a switch away, when needed). Oh, and it didn't leak any when submerged in the bucket.