Triple XM-L DIY Canister Light

Hi all. I'm new here but I've been reading around the forums quite a bit researching and thinking about building my own canister dive light. Would really appreciate some help as I'm a real noob when it comes to electronics and stuff.

Looking at this cheap dive light from ebay:
http://www.ebay.com.au/itm/261244474691?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

It claims that it can produce 4000 lumens. Knowing that it's powered by 3 XM-L emitters, it seems highly unlikely that it possible. Further, running only on 2x3.7v 3000mAh batteries, it is impossible to have any decent run time at that brightness.

Thus, I am thinking of buying it and modding it into a cannister light. I suspect that what is limiting this light will be the driver and was just wondering if there's any driver that you guys can recommend for this light. I've been looking at this:
http://www.taskled.com/techb3flex.shtml

And powering it with 6x18650 batteries connected with 3 in series to produce 11.1 v and then 2 of these in parallel to produce a burn time of about 2.1 hours. As I said, not even sure if my calculations are correct as I'm a real noob when it comes to electronics so would really appreciate some help.

Thanks!!

kymteo said:

Hi all. I'm new here but I've been reading around the forums quite a bit researching and thinking about building my own canister dive light. Would really appreciate some help as I'm a real noob when it comes to electronics and stuff.

Looking at this cheap dive light from ebay:
http://www.ebay.com.au/itm/261244474691?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

It claims that it can produce 4000 lumens. Knowing that it's powered by 3 XM-L emitters, it seems highly unlikely that it possible. Further, running only on 2x3.7v 3000mAh batteries, it is impossible to have any decent run time at that brightness.

Thus, I am thinking of buying it and modding it into a cannister light. I suspect that what is limiting this light will be the driver and was just wondering if there's any driver that you guys can recommend for this light. I've been looking at this:
http://www.taskled.com/techb3flex.shtml

And powering it with 6x18650 batteries connected with 3 in series to produce 11.1 v and then 2 of these in parallel to produce a burn time of about 2.1 hours. As I said, not even sure if my calculations are correct as I'm a real noob when it comes to electronics so would really appreciate some help.

Thanks!!

Click to expand...

4000 lumens...yeah, it's a llie assuming 3x10w the batteries might burn 30-minutes... Assuming your battery Amp hours aren't a lie too!

the b3flex or lflex with your purposes battery pack would work nicely.


Leaks.. Leaks.. Leaks are likely the biggest issue though

Codiak said:

4000 lumens...yeah, it's a llie assuming 3x10w the batteries might burn 30-minutes... Assuming your battery Amp hours aren't a lie too!

the b3flex or lflex with your purposes battery pack would work nicely.


Leaks.. Leaks.. Leaks are likely the biggest issue though

Click to expand...

Yea. Intend to counter the leaks by checking through all the O-rings on the light and also by ensuring that the glass thickness is thick enough to withstand the pressure.

Also, I have here a scale drawing of my canister. Going to make it out of PN18 40mm PVC to fit 6 18650 cells. Wonder what everyone thinks about this? Of course I haven't included the cable glands and the latches yet (gonna be hard to draw them =/) but just wanted to pick up potential pitfalls.



Once again, would appreciate any help at all!

Codiak said:

4000 lumens...yeah, it's a llie assuming 3x10w the batteries might burn 30-minutes... Assuming your battery Amp hours aren't a lie too!

the b3flex or lflex with your purposes battery pack would work nicely.


Leaks.. Leaks.. Leaks are likely the biggest issue though

Click to expand...

4000 lm? Of course it's a lie. 3000 mA-H in 18650? Of course it's a lie. 3x10W, not likely. You'd probably get 2+ amps when the batteries are fully charged, but the regulation is probably only mediocre.

Seems like I saw a review, or at least a thread, about this light. You might want to look for that before ordering.

Dealextreme and Kaidomain both sell variants of this light, without batteries and chargers. I don't know what the exchange rate is, but they might be a bunch cheaper. Didn't see a triple U2 variant, but you're just trusting that you'd actually get U2's anyway.

You are better off just starting from scratch. I would use individual drivers for each LED and 6 batteries in parallel myself. This will allow you to have very good efficiency, the closer your battery voltage is to your Vf the better and since the requirement for an XML is close to that of a lion batt. that is how I would proceed. You can also keep the draw relatively well distributed in this manner by converting several cells into what would act like one large cell. This would make your voltage droop very small since each battery would only be providing a total of 1.5A to the led. I would get XM-L2s that are already copper-mounted from a trust site like intl-outdoor or where you prefer like illumination supply wherever I have used both and I am satisfied with both. Wire the battery voltage to the drivers in parallel and the driver's output directly to its own led. You can also use this same technique to power one led from 2 drivers and double the current while maintaining the same voltage. Hope this is a help, and yeah leaks are the problem you are going to run into. You could always just get a Sky-Ray King or Kung and put it in a water-tight tube with a lens on one end, the run time wouldn't be great though.

Your burn time estimate is very reasonable. Here's how I would do it:

Load = 3.3V * 2.5A * 3leds = 24.75W

Supply = 3.7V * 2.5 A-H * 6 cells = 55.5 W-H

Driver is boost, 80% efficiency, so 55.5 W-H * 0.8 / 24.75W = 1.8H.

Now that's only a guess. It assumes you get good quality cells and the light has a mediocre quality driver. The cell capacity, regulator efficiency, and output current could be substantially different. Also, its very likely that the regulator output will drop as the battery voltage falls, slowly at first, then more rapidly as the battery voltage gets lower. So you'd probably get an hour at near full output, an hour or more at gradually reduced output, then anywhere from a short time to many hours at very reduced output.

Langham's suggestion is reasonable if you have room for three drivers. AMC7135 type drivers from dealextreme or kaidomain are cheap and pretty easy to work with. Anyone know if you can control three of them in parallel? That's the thing I would worry about.

But that assumes you can run the LEDs individually. I would bet that you'd have some serious mods to make before you can do that. It also assumes you want to ditch the existing driver and the variable output feature, and install your own drivers. It didn't sound like you wanted to do that. If you did, there are better hosts for that. And as the peak currents are in excess of 6A, you'd have to be a bit more mindful of your contacts, wiring, and soldering.

All in all, especially for a newbie mod, I think you are on the right track leaving the drivers alone.

I think that you can control them in parrallel as long as you keep them in sink the entire time. I would also go as far as to say that you should be able to have mode options as well. I was thinking of the same driver that you mentioned, but I would also agree that for a beginner that might be difficult especially since there would have to be a switch that could take 9A or so. I will just have to find a buyer and do these modifications to my Kung that I just got. The stock body is amazing, but the circuitry and wiring is appauling.

Thanks so much for the info guys! After reading your comments I think I am going to proceed in the following stages for mod-ing this light.

1) Mod the cheapo dive light into a canister light using the current driver hardware
2) Swap the driver on the cheapo dive light to try and increase the efficiency and the current
3) Possibly do a mag lite mod in the future using langham's suggestion.

Does this sound like a reasonable path to adopt?

I don't like Mag lights, but other than that go ahead. Just remember that it gets addicting, I had 30 lights at one point and only 3 that worked. I should spend more time doing build threads, but I am always so busy modding lights I just can't find the time. If you don't have the mag light yet I would recommend just getting one of the Sky Ray king bodies for your mod, they already use 18650s and the body is built very well the only issue is the circuit.

Thanks heaps for the advice guys! I will be prodding along with the project and updating it here along the way. Still open to any input you guys may have and I'll be counting on it.

You may find it very difficult to fit a new driver in the head. You could always put it in the canister though! Might want to leave a little room there for it. You'll know better once you get the light.

DIWdiver said:

You may find it very difficult to fit a new driver in the head. You could always put it in the canister though! Might want to leave a little room there for it. You'll know better once you get the light.

Click to expand...

The only problem I can foresee with this is the difficulty in heat dissipation considering that I'll be using PVC for my canister. Yea. I guess I'll have to figure it out when I actually receive the light.

Depending on the driver, you may not have much heat to dissipate.

You also have to account for the much higher efficiency from water rather than air as your heatsink. You shouldn't have that much trouble.

I was just thinking that PVC might not do so well with any heat at all and might soften or cause leakages.

New question: What material of O-ring should I use for the canister? Does it really matter?

kymteo said:

New question: What material of O-ring should I use for the canister? Does it really matter?

Click to expand...

I tend to use Nitrile 70...
Just make sure the material matches the expect environment, and the groove matches the hardness.

http://www.oringwarehouse.com/o-ring-materials/?gclid=CMqb3OnZr7kCFcvm7AodShgAaQ

Codiak said:

I tend to use Nitrile 70...
Just make sure the material matches the expect environment, and the groove matches the hardness.

http://www.oringwarehouse.com/o-ring-materials/?gclid=CMqb3OnZr7kCFcvm7AodShgAaQ

Click to expand...

Also, assume at least one failure! in other words either seal the can or use multiple orings