First Build - Work in Progress but feedback welcome

Hi All,
this site has inspired me to build a dive light.... i've absolutely no engineering skills or equipment so its very rough round the edges and everything has been sourced to make my life as straightforward as possible, but is the outcome flawed?

So, any good ideas for improvement i'd be very grateful... Its not flooded yet but its early days...

I've written a blog to capture it all... at http://johnohuk.blogspot.co.uk/

The head unit... cut down 3d maglite with 5 *CRE from DX



Canister ( or rather test tube.. you can laugh at this point but it has been to 30m no probs (110ft)



A beam shot from my local diving pool ( not nice particulates)... The wall is about 5-6m away...at a depth of 4m, in the dark.

Great job! How long does it last? do you the standard driver from the dropin? where did you find that canister I love it!!!

Daniel

Hi Johnno,

Thanks for sharing.

I find it interesting to see all sorts of mods here, from the simple with few tools to the very sophisticated. Excellent to see that with few tools and even fewer dollars you've made a decent torch that works. I'd be interested to see how the glued stepped lens compares against a machined stepped synthetic for lumens transmission. You can also go the 5-6mm boro glass route without stepping. Truth be known if 35M is as deep as you want to go and with a 52mm host then you'd probably get away with 4mm (which give you more thread when screwing the bezel on).

I like the simplicity of the 'test tube' battery pack. Can I ask why you did not want to have the battery compartment in the handle itself, and do away with the wand/cable/canister design? For a 1200Lumen drop-in such as this you're looking at about 15watts power draw so having two D-Cell Li-ions in the handle makes for a compact torch with enough power for at least two dives (a days diving). Just a thought.

I am also thinking that with a good tug on the wand that canister plug is going to come out...flooding the canister. Have you thought about securing the cable to the canister with a few wraps of gaffa tape or a cable-tie for a bit of strain relief?

Nice work with the angle grinder on the head. You make do with the tools you have.

Hi Guys,
thanks for the feedback.... i'd never thought of the lens might impact lumen output... think i'll try that..

Depth range i want it to handle is 45m (150ft) absolute max, .. but mostly in the 35m (115ft) -25m (80ft) range..

Do you think I need to step up to a boro lense for that?

Light pulls about 1.6A at 8.4V so 13W... with those cells I can get one hour runtime, which is way down on what i thought I would get... I think the batteries are not right... need to retest.. and upgrade the batteries..? They are rated at 2500mAh but i'm not so sure about that..

An hour burntime is too short for me... as most of my diving is a 2 dive day i.e. deeper 40mins + 50mins shallow I need something to cover 1.5hrs at least.. better 2+ hence my next step was to increase the batteries to 2S2P i.e. double what it is now...I'll still use the tube method but just a bit longer... the existing one is 12" long ...a one meter length is on order which i'll cut down..

The drop-in is using the standard 2 mode driver, I didn't realise you could remove it ! Probably best to remove it before grinding it as the grinding process deforms the board/head metal and may not be so easy to get out now...

The drop-in max voltage (8.4v) is a pain... it makes the tube wiring more complex if I want to add more batteries... as they have to be 2S2P...to keep within 8.4v but ideally it would be better if it was 4S at 16.8V for simpler tube wiring..

Is it better to have batteries in parallel rather than serial if the dropin voltage wasn't an issue?

The "canister" is just Acrylic/Perspex tubing, used in shop displays/craft work and seems to be freely available on ebay.. The wall is 2mm thickness but u can get it in 3mm thickness... maybe better if you increase the diameter to fit bigger batteries..?

The rubber bungs or stoppers are from a laboratory supplier for schools, again off ebay... As long as the inside diameter of the tube is somewhere between the max/min of the bung it seems to seal fine..

Definitely, need to secure that wire end... probably tie wrap it to start with... I tried freezing the stoppers and then placing them in the tube but they don't contract so no benefit to the sealing process there!

Thanks for the input..

John

John,

OK, they are two 18650 batteries in series.

The cheap and cheerful Chinese 18650's bought on Fleabay, DX or KD have often overstated capacities. Add to that the slight voltage drop of the driver when under load (especially with only two 18650 batteries) and you will reach the protection circuit's cut-off voltages quicker than your calculations. I take it both batteries have a protection circuit, i.e. they are, 'Protected'?

Yes, you have to stick within the voltage parameters of the driver...8.4V, two cells. if you want more glow time then that means more cells in parallel or larger cells like 32600's (D Cells). 18650's are the cheaper option however.

You could go 4*18650 in a longer test tube canister and have the positive take-off in the middle of the four batteries and the negative coming from both ends to give the 2S2P configuration. So, they all point inwards to the middle of the canister.

You don't have to go glass for the lens if you don't want to. I use both and they will all work in your situation of 13Watts of heat generation in a Maglite and to 45M depth. Glass is a little clearer but more brittle relative to synthetic ('Perspex'/acrylic, or 'Lexan'/polycarbonate). The benefits of lens choice is covered comprehensively in previous posts. Certainly using glue, albeit translucent, between two lenses is going to shave some light transmission off the potential.

Cheers for the quick and concise response !
John

Get some Sanyo 2500mah cells. They have true rated capacity... Well, may be about 100mah less. They can do 2C drain rate too...

Very nice build! Did you put any silicone or glue when between the lens and the bezel?

HI BeeKeeper5, just greased up the o-rings with silicon grease... not too much..just enough between two fingers and run the o ring through... same stuff I use on the camera o ring..

John

Re: First Build - Work in Progress but feedback welcome - update

Just a quick update...

New tube created to fit 4 18650 batteries, positive take off in the middle and a different brand of battery (xtar) now giving me an approx runtime of 3hours... much better..

Just now waiting for my next half decent dive depth wise.... probably going to be 15m (50ft) in 3 degree C water next week.... brrrr...

Some pics and blog updated... http://johnohuk.blogspot.co.uk/





DX glass optic has finally arrived so will give that a go as well...

Re: First Build - Work in Progress but feedback welcome - update

Very good!

What glass optic are you talking about? That drop-in uses a reflector to focus the light so does not need an optic.

Re: First Build - Work in Progress but feedback welcome - update

The glass optic I thought I needed but now know that I don't.. oh well...

Re: First Build - Work in Progress but feedback welcome - update

Can you tell us more about what type of lens and O-rings you used between the lens and the bezel? I'm having a hard time keeping mine water tight. It keeps leaking at the lens.

Re: First Build - Work in Progress but feedback welcome - update

Howdy beekeeper...

Not sure if this helps... in an unstructured way...

Mine leaked as well to start with.. the clincher was when I took enough of the drop-in off for it to be completely flush with the rim of the maglite head ..Nothing protruded... AND the 5mm stepped lense..

The lense was a two part acrylic piece a chap off ebay was selling... two sheets of 2.5mm glued together to give 5mm. One is a smaller diameter and keeps the o ring aligned with the rim of the head ... against the top sheet of the lense.

I tried a few different thicknesses as a friend can laser cut arcylic.. thinner ones didn't work...but too thick and you can't screw the head down enough...

I upgraded all of the o-rings to the ones recommended on this website (or someone's elses light website

The o-ring in the base was removed.. and I filled it with gasket sealant and screwed tight and left to dry...

The cable gland was liberally covered with silicon grease...

To debug the leaking... i tried to isolate the leaks by filling it with water with the tail cap end on and leaving over night .. when i was happy it hadn't leaked I did it the other way round..lense on and fill from the back...

I also went diving quite a bit with an empty canister/head to make sure it was water tight at depth before putting the electronics in..

You will doubt yourself but it is possible!!

John

btw the exact spec of the o rings is in my component list on the blog...

Re: First Build - Work in Progress but feedback welcome - update

Hello John, I've been putting an o-ring between the head and the lens. For some reason, the o-ring just sits in the rim of the head with little to no contact on the lens. I've put tons of silicone around it to compensate but the marine silicone eventually turned yellow and brittle (no idea why). What keywords did you use to get those acrylic lens off ebay? Sorry for the lack of newline spaces. My "enter" button just decided it doesn't want to work in this forum..

Re: First Build - Work in Progress but feedback welcome - update

Hi...i just checked and the guy is not selling the 5mm lense anymore... ;( but I googled "5mm lense for maglite" / "5mm stepped lense" and it came up with a few examples of this build type... they suggest a glass lense of 5mm ...worse case i'll ask my mate to make some !

I found..

http://www.shiry.me.uk/dive_light.php

http://www.candlepowerforums.com/vb/showthread.php?320316-1200Lumen-Maglite-Upgrade

Not sure about the silicon, the casket stuff i used just sets clear.... do u have any JB weld? what drop in are you using?

John

Re: First Build - Work in Progress but feedback welcome - update

best not use the jb weld just yet... wait till u get lense sealing with the head....

Re: First Build - Work in Progress but feedback welcome - update

I use the strongest glue I can find on the lens-to-bezel seal. Gasket seal is about the weakest seal there is when it is under the pressure at depth. I only use this on seals that will be opened on a regular basis. The service access seal to the wand is the bezel-wand, not bezel-lens and it pays to have fewer access seals into the wand as possible. one is enough.

My point is why don't you make the seal between the lens and the bezel permanent? Not only that, if you can make the seal strong enough that it does not have to rely on anything else to withstand water pressure (like screwing it up as tight as you possibly can hoping there's enough metal proud to push against the lens) then that's one less point of flood you have to worry about.

I've had a torch flood when thinking the drop-in would be solid enough to push against a fatter replacement O ring in the bezel. I've gone back to using stepped perspex lenses glued with epoxy putty to the bezel (no O ring). A solid 5mm thickness of perspex with the lip cut out on a lathe.

Re: First Build - Work in Progress but feedback welcome - update

beekeeper5 said:

... My "enter" button just decided it doesn't want to work in this forum..

Click to expand...

Mine too. Are you running W7x64 like me? I open Notepad, hit enter twice, copy and paste into the post and get new lines. I would be grateful if someone offered a better solution.