Thread: Dive light project - My plans so far

1. Dive light project - My plans so far

OK so my planning is getting somewhere. Here's what I have so far:

Emitters and optics:
4 x Cree R2 (WG bin) focussed with aspheric lenses. Driving them at 1050mA, the R2 emits about 270lm according to this post. Using the 30mm ones that ahorton is selling should allow me to collect a large amount of light from each LED, and focus it very tightly.

Using the following formula for the inner bezel diameter requirement:
D = d * sqrt(2) + d
(where d = the diameter of each individual lens)

Gives me a bezel inner diameter requirement of 72mm. Assuming a 4mm thickness (should be able to do better, but worst case) that gives me an 80mm head. Not small, but not too large I think (comments on this welcome).

If I were to trim off the flange from the lenses (2mm) then the lens dia goes down to 26mm, which would mean that the inner bezel size would be reduced to about 63mm, allowing an outer size of about 70mm. A bit better.

Circuitry:
The LEDs will be wired up using a single 1050mA AMC7135 driver board from DX using the nifty circuit shown on this page. I will remove the diode from the driver to increase efficiency.

There is no need for multimode, if I ever need less light for close up work I'll put a diffuser over the front.

Battery can:
The battery canister will contain a string of batteries in xP4S configuration. The x is because I haven't decided how many parallel batteries to put. I have also not decided what batteries to use.

I could use 3P4S x 18650 batteries, giving a can about 350mm long, 45mm in diameter and holding 7200mAh. That would be a very narrow can, so I could do 4P4S increasing the diameter to about 50mm and increasing the capacity to 9600mAh. 4P4S seems OK to me, but I've never used a can light before so I don't know if 350mm x 50mm are reasonable dimensions. Packhorse? Any advice?

Another possible arrangement would be a 7P4S arrangement of 14500 cells, which would give me a 50mm dia can roughly 250mm long holding about 6300mAh. 7P4S of 16350 (RCR123A) batteries gives a can 200mm long and 55mm in diameter, holding about 6000mAh.

The dimensions for the 7P4S 14500 and 16340 cells seem more pleasing on paper, but the energy density is obviously far lower. Bear in mind, though, that I will be drawing 1A from the pack, so even these packs would provide well over 4 hours of runtime, which would be enough for two or perhaps even three dives between charges. The other advantage of the RCR123A pack is that batteries are cheap and easy to come by anywhere. That being said, I'd prefer the larger capacity, if those dimensions are still within acceptable size for a light can.

If anyone has any advice, tips or general opinions on what I'm planning here, it would be greatly appreciated. Thanks in advance guys and I await your words of wisdom.

3. Re: Dive light project - My plans so far

Originally Posted by 300winmag
I thought that the proposal to have a dive specific forum was rejected?! I'm very glad it's not! How do I move my thread there? Or should I just repost it?

4. Re: Dive light project - My plans so far

The aspherics from Ahorton work really well with XR-Es
but a 80 mm head is huge. Even 70mnm is big.
You could grind down the lip on the lenses ( as I have done) and you get about 27mm.

As for batteries first you need to work out how much burn time you need the double it. I say double it because the batteries may not always be fully charged and you should have some redundant energy for longer dives.

Example.
You do 2 dives a day. Each dive lasts for 1 hour but chances are your light will not be on the whole time. Say 45min.
So you need 1.5 hours burn time.
Double that to 3 hours.
a 2P4S using 18650's at 2500ma will give you 4 plus hours with a good can size of about 200mm long and 65mm wide. Extend it to 270mm if you want 3P4S setup.

I would also recommend you look at a multi mode set up.
The light you are building will be very bright. Brighter than mine. And I use my mid mode alot. Low not so much.

5. Re: Dive light project - My plans so far

Originally Posted by Packhorse
The aspherics from Ahorton work really well with XR-Es
but a 80 mm head is huge. Even 70mnm is big.
You could grind down the lip on the lenses ( as I have done) and you get about 27mm.
In the past you've advised me that overly big light heads are problematic. My current dive light, a Princeton Tec Miniwave, has a 75mm outer diameter. It's a pistol grip light, and I don't find it to be too big. An extra 15mm would not be too much of a problem. I've only ever actually used it under the water on three occasions, so my dive light experience is fairly limited. Is there any reason that a dive head this size is problematic?
Originally Posted by Packhorse
a 2P4S using 18650's at 2500ma will give you 4 plus hours with a good can size of about 200mm long and 65mm wide. Extend it to 270mm if you want 3P4S setup.
Perhaps I'm misunderstanding something. I thought thatwhen using xPyS to represent a battery pack, the x was how many batteries were side by side, and y was how long the pack would be. However, you're increasing your length by boing from 2P to 3P. Are you using a wiring pattern to series the batteries that are side by side and the parallel the resulting units?
Originally Posted by Packhorse
I would also recommend you look at a multi mode set up.
The light you are building will be very bright. Brighter than mine. And I use my mid mode alot. Low not so much.
I like that this light will be "very bright" . Given that I planned to use a 1050mA AMC7135 based board, what would you recommend would be the best driver? I saw this KD P7 driver that you recommended in another thread, and already have purchased two of them so I can use those if you say they will power the light well. However, I've never used anything more complex than a AMC7135 yet, so it's all a bit scary. Would a 2P2S arrangement powered by this driver be better than using two separate AMC7135 based boards and just switching between them?

6. Re: Dive light project - My plans so far

Originally Posted by MrNaz
In the past you've advised me that overly big light heads are problematic. My current dive light, a Princeton Tec Miniwave, has a 75mm outer diameter. It's a pistol grip light, and I don't find it to be too big. An extra 15mm would not be too much of a problem. I've only ever actually used it under the water on three occasions, so my dive light experience is fairly limited. Is there any reason that a dive head this size is problematic?
If its big then it is cumbersome. I like canlights with a goodman handle. I would imagine something that big would be a pain with a goodman handle. It may be fine with a pistol grip.

Perhaps I'm misunderstanding something. I thought thatwhen using xPyS to represent a battery pack, the x was how many batteries were side by side, and y was how long the pack would be. However, you're increasing your length by boing from 2P to 3P. Are you using a wiring pattern to series the batteries that are side by side and the parallel the resulting units?
3P4S represents 4 lots of 3 parallel cells in series. It matters not how they are arranged. You need 4 cells in serries to get 14.8 volt. And another 4 cells that are also in serries and parallel them up to the 1st and you now have 2P4S. This will give you 5ah 14.8volt pack from 8 2500ma 3.7v cells. Thats enough to drive your 4 XR-E's @ 1050ma for over 4 hours. At least 2 hours will be at full power as the voltage drops so will the lumen output and the current consumption. Since the current is lower the battery pack will last longer. Perhaps 6 or 7 hours or reasonable light output.

I like that this light will be "very bright" . Given that I planned to use a 1050mA AMC7135 based board, what would you recommend would be the best driver? I saw this KD P7 driver that you recommended in another thread, and already have purchased two of them so I can use those if you say they will power the light well. However, I've never used anything more complex than a AMC7135 yet, so it's all a bit scary. Would a 2P2S arrangement powered by this driver be better than using two separate AMC7135 based boards and just switching between them?
You could use that driver. I do and am pleased with its performance.

You could run all 4 XR-E's parallel giving each (2.8a/4=) 750ma. If doing this then go for a 4P2S pack @ 10amp 7.4 volt. I have built 2 can lights in this configuration with maglite heads and smaller aspherics. Works great but the 30mm aspherics will work a bit better at the cost of a much larger light head.

Or you could run the LEDs 2P2S. This will then make the driver put out about 7.4v(2x Vf) at 2800ma. Each LED will be over driven at 1400ma.
This is how my own can light is configured. It consumes twice as much power as the other option and gives about 50% more output. LED life is probably reduced quite a bit. You do neen more voltage to run it this way ( I use 9.6v NiCd). I would suggest 3P3S or 7.5a 11.1volt. I would have 1 row of 5 cells and 1 row of 4 cells to keep the cannister shorter. They should fit in a 65mm ID can OK.
Both of these two options using the KD driver will run at full power untill the battery pack voltage drops to 5.5 volt (7.4v battery pack) or when the battery protection circuit kicks in for the 11.1volt pack.

7. Re: Dive light project - My plans so far

Thanks for all the info. Given the cold white tint chart here:
http://img170.imageshack.us/img170/8...pcwfulloe4.jpg
What would you say is the best tint for a dive light? I already have some R2 LEDs in the WG bin, but I was thinking that cutter has the WH bin LEDs and they may be better for a dive light. Is it worth buying a bunch of WH tint LEDs?

Also, perhaps warm white LEDs would be better? I'd be sacrificing lumens for output, but perhaps that would be a better solution for piercing through blue water. What's your experience with underwater LED tints?

8. Re: Dive light project - My plans so far

Originally Posted by MrNaz
Thanks for all the info. Given the cold white tint chart here:
http://img170.imageshack.us/img170/8...pcwfulloe4.jpg
What would you say is the best tint for a dive light? I already have some R2 LEDs in the WG bin, but I was thinking that cutter has the WH bin LEDs and they may be better for a dive light. Is it worth buying a bunch of WH tint LEDs?

Also, perhaps warm white LEDs would be better? I'd be sacrificing lumens for output, but perhaps that would be a better solution for piercing through blue water. What's your experience with underwater LED tints?
have a look here..http://gakuranman.com/colour-in-the-deep-sea/

I'm about to test a WG tint MC-E in green water. The general gist from that link seems to suggest blue tint for blue water, and green tint for green water..
I have some DX R2 WG xr-e's and the tint is vastly different from a WG tint MC-E from Cutter. The DX ones seem much more cold and blue..

9. Re: Dive light project - My plans so far

Yeah, idealy you want to match the tint of the LED to the tint of the water. But I wouldnt worry about it too much.
Warm white LEDs will give a much more natural light but it will not be as bright. I would give these a miss unless you are building a light for still or video work.

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