New Light

Hi guys, I am a total noob at electronics so please dont be peeved at me for my innocent lack of knowledge.

I built a pair of dive lights based on the design of Martin Els ( https://www.youtube.com/watch?v=mNyG29Ciy_M , https://www.youtube.com/watch?v=NDZX7UP-qes&list=TL1yGfDHDBkoxZdeaRJ759XrLqn3PBXJss ). Im sure its my fault, but I just dont feel like Im getting the light throw that I want from these. Ive seen his videos from post production and his lights seem to work way better than mine, but due to differences in the types of parts available here and in South Africa I cant build them quite as solidly as he did without some special milling tools that I dont have and dont know how to use. I digress. I was considering a whole new design and wanted to bounce the concept and some of the technical ideas off you guys.

#1- I want to make a rectangular mount ( https://www.google.com/search?q=diy...mounts-worth-browsing-t1969-270.html;1024;768 )for my Gopro that is easily gripped by either one, or two hands. And if you watch the linked video you will understand, I want to remove the mickey mouse ears and put the lights either directly above and below or left and right of the camera housing. but instead of bulky lights that hang out of the back of the camera frame, I want to make a tube light that exposes 3-4 Cree XML T6 lights lined up in a row so that the light housing can be mounted flush to the camera frame.

#2- I want to use a single cell Lipo battery to power each light pod. I am experienced with Lipos through the world of R/C so I am aware of the "dangers" associated with Lipos. But for the cost to performance ratio they offer I dont know that you can beat a Lipo. My biggest issue revolves around the power system. I dont know enough about electronics to accurately and properly design the correct wiring layout for what I want to do. I can muddle my way through the hardware, its the electronics that matter more to me. My last build was with standard AA's, which I think led to my poor performance, so this time I want the max (safe) amount of juice going into my LED's and coming out of them.

I know my design may not be practical. My desire to use a Lipo may be out of line. I recognize that and am willing to listen and make the changes that I need to make in order to do this right. What I really would like is for someone to help me design the electronics but to also help me understand what it is Im dabbling in so that I can eventually do it on my own. I will gladly accept any and all feedback.

Well, I toned it down some.
I went with 4 new Cree T6 emitters, (2 per light) 4 drivers, and each light will run off of 2 18650 4000 mah batteries. Once I get the parts in I will determine what size tube I need to house it all. I found some decent clear tubing that's 1/8" thick that I plan to use for the main body. Still working out how I'm going to seal it, but I have a few ideas I'm considering. I will most likely use a reed switch with a rotating ring as a power switch. If all goes well I will be pushing about 1500 lumens per light. In our murky water that should help tremendously. Hopefully my batteries can take the strain.

Hi, and welcome to the forum!

A couple of things jump out at me:

Packhorse made some video lights in tubes. You should definitely check out his build library.

I love the magnet in a ring for switching. It's in my first and third (latest) light builds. But you have to be aware that it can get fouled with sand or iron particles (prevalent on wrecks, and attracted to the magnet). My first light had a ring that was cut in half, and held onto the light with an o-ring (like a rubber band). It's great because I can clean it at 100 ft with 5mm mitts on.

18650 cells rated at 4000 mA-H are very likely overrated, probably substantially. I think the best currently available are probably 3500. The thing is that a vendor that overrates his cells doesn't buy high-quality cells and overrate them a little. He buys cheap crap and overrates them a lot. Of course I could be wrong. It's happened once or twice before in my life ;-). You could be talking about the very latest state-of-the-art cells. But when buying SOTA cells, you will pay premium prices. If you are getting SOTA specs at bargain prices, something is wrong, and you should probably run fast and far.

Why would you go for T6 LEDs? Those are two generations behind. Get XM-L2's, U2 or U3 bins. For an extra buck or two, you'll get substantially better performance.

You say you want to use LiPo, then say 18650. I think that probably indicates that you learned that the 18650 is the best bang for the buck that you can get currently, and acknowledges that LiPo and 18650 are mutually exclusive. Just wanted to make sure that's part of the general conversation.

To get 1500 lm out of two XM-L's is a very reasonable goal. You don't have to push them to their limits to achieve it.

My current lights use the ring and after 2-3 dives they froze. I just ended up splitting the rings with a dremmel. Problem solved. It was something I tried to plan for and I had tried to sand in some extra free space to prevent it, but lesson learned.

I went with the 18659's because that just seemed to be trend. In R/C they use lipos on LED light strips but the strips come pre-chipped to regulate a lipo battery. I don't know enough about electronics at this point to A) figure out if a standard Cree driver/LED can take the punch from a lipo, and B) how to throttle it back to make it work if it is too strong. Hobbyking sells 1 cell lipos that run up into 5000 mah's in the $10-$20 range so costs really aren't all that bad to me. I highly doubt that the 1860's I bought are SOTA. But for the price it was worth the gamble. Even off of LED sites they aren't expensive so if these fail I'll still have a charger.

As for the T6, I didn't realize they were behind the 8 ball. Thanks for the heads up. I'm still waiting for my offer from eBay to be accepted. If its rejected, I'll look at the upgrade. If I'm locked in its okay, its still a solid emitter. I'll have to search for the lights packhorse made and see what knowledge I can glean from him. Probably will save me some pain and head scratching in the RAD phase.

Thanks for the input. It is very much appreciated.

Here are some pics of my current light. I thought I had pics of my frame as well but I don't. You can see it in the background though.

Lost the deal on the T6's. I got the XM-L2. All my parts are in route.

Nice! I'm very interested in how they turn out underwater. I too saw that youtube video, but I was discouraged by the conversation about heat dissipation, or lack there of. Have you noticed any build up in heat?

There was no issue. I used a nice thick heatsink in mine. I was also just running AA's. Martin used 18650's and I think his got a little warm. With a single LED on 3.7v I don't think heat will be an issue.

Nothing like finding our your xxxxfire batteries are probably gonna end up a waste of cash. Looking at the keep power brand. The 'fires will get me started at least.

debay777 said:

There was no issue. I used a nice thick heatsink in mine. I was also just running AA's. Martin used 18650's and I think his got a little warm. With a single LED on 3.7v I don't think heat will be an issue.

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Good to know.

How did you cut the lens? What size of an o-ring did you use?

Sorry to keep pestering you, but I find this really interesting.

Sadly, the lens is just a piece of lexan. I forget the thickness but its probably a little too thin for much past 60-80'. I don't have any data to back that up, its just a hunch. The oring I bought to size and I don't recall the specific number.

Martin had several things going for him that I did not. First off he used decent batteries from the get-go on his design. That made a huge performance difference between mine and his. So his lights throw a much stronger beam.. well nit so much a beam as a flood actually, and work better than mine on AA's. Additionally, the pipe fittings available in South Africa vary greatly to what's available here in the states. The biggest difference being the thickness and shape of the fittings. Where his lens cap screws on is a nice fat ledge that forms a perfect o-ring ledge. I had to fabricate mine. Having a lathe would be beneficial but ai just don't have one. Also, american threaded fittings tend to be conical so that the further you screw a cap on the tighter the seal. Not so for martins parts Both of those issues aside I didn't like the over all performance of the entire rig. One handed manipulation is difficult especially in a current. I also found that my camera lens was often taking hits when laying down the camera. Again, its probably my fault, but the way the beam of light flooded I never really got the pattern I wanted. Apparently with gopros some folks have found that rather than mount lights on the ends of pods, they mount them next to the camera in a way that evenly spreads the light directly in front of the camera. Gopros tend to do well close up and with my lights it was impossible to keep the beams focused in the right space each time I moved to a different spot to film. Its my hope that my new design will achieve an instant spread at the camera and allow me to get very clear and well lit video. I think the new design will be lighter, smaller, brighter, and easier to manage in and above the water.

My goal is to build a rectangle so that no matter how I turn the camera I can have a squared 2 handed grip. Additionally, I will have a single handle mounted vertically directly behind the camera so that one handed manipulation will be more balanced.