DIY Powerfull LED Dive Light

Pizeer

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I am starting a diving light project.
I don’t know much about electronics, but been reading lots of forums on DIY lights.
I want the light to have an output of over 2000 lumens, and since it will be an underwater light, heat should not be an issue.
I am hesitating between one or more SST-90 LED or 3 x CREE XM-L U2.
Requirements:
+ 2000 lumens
ON/OFF Magnetic switch;
Smallest possible;
Buck Driver with only mode, ON or OFF;
Battery types: Li-ion, Qty unknown;
:sssh:
:confused:
Do I really need a driver or only a Constant Current Power Supply?
What is a PCB?
Do I need the star underneath the LED emitter, or can I just fix it directly on the heat sink?
 

Mooreshire

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You can mount diodes directly to a heatsink without using a "star", but be aware of whether the heatsink is electrically conductive and plan accordingly.

PCB stands for Printed Circuit Board - so, any circuit board newer than 1950 or so is likely a PCB.

Yes you'll want to use a driver, otherwise your LED won't last long.

Good luck, and please share pictures when you're done. :)

(Here is an old XM-L versus SST-90 discussion.)
 

Packhorse

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I think you have left out the most important piece of information.

What sort of beam do you want to produce?

Its pretty easy to make a 2000 lumen light extremely small ( excluding the battery pack of course) But to make one that can produce a tight beam will require a large optic. And in the case of multiple LED's multiple large optics.
 

350xfire

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Since you don't know much about lights, I suggest building a respectable single-LED Cree XML first. You can use a complete module from DX with reflector, LED and driver which will run about $20. Use a Maglite head to house it in. Then working from there. You should really get a good understanding of how it all works and save yourelf a bunch of frustration in the long run.

Once the single LED system is done, start expanding to better drivers, different reflector combinations, multi-LED, etc...
 

Pizeer

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I am thinking of a 6 feet in diameter beam from 10 feet away, flood type beam.
Here we dive in the St-Lawrence River and visibility is not so good.

Let me know what you think.

Thanks
 

Codiak

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I am thinking of a 6 feet in diameter beam from 10 feet away, flood type beam.
Here we dive in the St-Lawrence River and visibility is not so good.

Let me know what you think.

Thanks

i dive low vis all the time.. Floody lights are not something I apappreciate the beam you describe would not be difficult
 

Packhorse

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In bad vis I prefer a tight beam that will cut through the water instead of a wide beam that will produce a lot of back scatter.
 

Pizeer

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In bad vis I prefer a tight beam that will cut through the water instead of a wide beam that will produce a lot of back scatter.

Well, I am diving with a Princeton Tec Miniwave Led and it is not enough.
On of my buddy has a HID light and that's some light but not very durable.
 

DIWdiver

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You also need to know how long it needs to run in order to calculate how many batteries you need.

The bare LED (often called the emitter) has a metal plate on the back side. Some have only one for heat dissipation, some (including both that you mentioned) have two additional pads on the back for electrical connection. On some emitters the electrical connections are on the front. When they are all on the back, the trick is to get the center pad really well connected to the heatsink, and still get the electrical connections out. I've seen pictures of special copper mounting brackets that have a narrow portion in the center where only the center pad is soldered directly to the copper, and the electrical connections hang off each side, so wires can be soldered to them. Its really an awesome way to do it.

But most of us haven't the will or ability to do that, which is where the star comes in. It's a special PCB with metal core (aka MCPCB). All three pads of the emitter are soldered onto it. The thermal pad had very good (but not awesome) contact to the metal core, which transmits the heat to your heatsink. The electrical pads are brought out to the sides so you can solder wires to them. If you aren't going to design your own MCPCB or fancy copper heatsink, the star is about the only way to go, other than buying a module with emitters installed.

A driver IS a constant current power supply. I make and sell a very simple one based on an old and well-known linear constant current circuit. Unfortunately it doesn't play well with LiIon cells. Ones that do are usually switching supplies. They are more sophisticated and if well designed can keep the emitter safe and running at or near full brightness for most of the battery life. But as with anything else, there are good ones and bad ones, and some in between. Good ones should be reliable, efficient, and deliver the promised performance. Bad ones tend to be less efficient, less reliable, and offer performance that just doesn't measure up to claims. Often the output isn't as 'constsnt' as you'd like as the battery voltage or LED voltage changes, even within the specified range. Good ones will be rock solid, or pretty close.

Efficiency is a measure of how much of the battery power the driver sends to the emitter. The driver will always consume some of the power as it passes through, converting it to heat. A good driver can have an efficiency of 90% or even higher, while cheap ones tend to be in the 60-80% range. A good driver can increase your battery life 30-50% over a bad one, at the same brightness.

The best drivers are in the $30-40 range, the cheapest are under $5. But cheap and bad are not always the same. There are some very inexpensive drivers that don't suck. But if you're paying $1.99 for the driver and $2.89 for shipping, you are taking a chance on what you'll get. At least it's a cheap gamble.
 

Pizeer

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Wow, thanks for all this info DIWdiver.
I have a lot of reading to do I see, but this is really helping.
I will design the light from scratch, since I have access to Catia V5 & V6.
I plan to have a canister for battery like most high power diving lights, but don't know yet if I'll be using LiIon cells.
So far, what I have been reading on SST-90 vs XM-L leds tends toward Cree XM-L.

SST-90 vs SM-L
 
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350xfire

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For low vis, a tight beam and not a huge amount of brightness is probably best. Huge brightness = huge backscatter which will drive you nuts.
For a nice simple system start with an XML system. If you want the one of best drivers use Taskled. The XML is designed to run at 3-3.5 amps and with 8XML (2S4P) you can get 5-6 hours burn time. The XML is rated at 1000 lumens and has a nice tight beam. You can get the DX $20 reflector/driver/LED combo, gut the driver out and tie in the Taskled or just use the stock driver.
 

Packhorse

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For low vis, a tight beam and not a huge amount of brightness is probably best. Huge brightness = huge backscatter which will drive you nuts.
For a nice simple system start with an XML system. If you want the one of best drivers use Taskled. The XML is designed to run at 3-3.5 amps and with 8XML (2S4P) you can get 5-6 hours burn time. The XML is rated at 1000 lumens and has a nice tight beam. You can get the DX $20 reflector/driver/LED combo, gut the driver out and tie in the Taskled or just use the stock driver.

The XML is designed to run at 1.5 amp's but can run at up to 3 amps as per manufactures recommendations.
But yes, there are many that run them at 3.5 amp( or more) with out issue.
( and I think you meant 8x 18650's not 8XML)
 

hydropower

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Sv: DIY Powerfull LED Dive Light

You can mount diodes directly to a heatsink without using a "star", but be aware of whether the heatsink is electrically conductive and plan accordingly.

PCB stands for Printed Circuit Board - so, any circuit board newer than 1950 or so is likely a PCB.

Ahh, yes, BUT! PCB can (unfortunately) also stand for Protection Circuit Breaker, the Li-ion battery protection circuit. It is not a good name but common...
So for the question: it depends on the situation what it means...
 

350xfire

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The XML is designed to run at 1.5 amp's but can run at up to 3 amps as per manufactures recommendations.
But yes, there are many that run them at 3.5 amp( or more) with out issue.
( and I think you meant 8x 18650's not 8XML)

yes, 18650 not XML... Thanks
 

Pizeer

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Does anyone has any temp reading of the Luminus SST-90 LED or 3 x CREE XM-L U2?
if I built a dive light, I would guess that I should not worry much about the heat dissipation...
How can I control the heat if the light is turned on outside of the water?
 

350xfire

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The Taskled Flex models have programmable temp shut offs. The only thing is that the driver has to be close to the LED or you have to run the LED until critical temp is reached then program the driver to shut off at whatever temp it is when LED critical temp is reached. Hope that makes sense...

The Flex drivers can be programmed for temp, voltage, turn on safety, turn off safety (safety by way of how many presses to turn on and off), etc, etc. There are about 14 menus to program. A bit overwhelming at first, but once you get used to it not bad..
 

Packhorse

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Another way is to install a thermal switch in line with power supply. I do this in my small high power video lights. They will only run for a minute out opf water before the thermal switch kicks in.

While you dont have to worry so much about the size of the heat sink, you do have to make sure that the LED has a good thermal path to the water.
Usual scenario is LED-star- aluminium heat sink-aluminium light head body. Each step must offer a good contact surface area.
 
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