BTU Shocker Triple MT-G2 with a twist -- Aiming for >100Watt ~9000Lumens -- With external 2S power pack, handle etc...

Yes I think a good XLR will do fine even at those higher currents. In fact I know mine will work fine since I tested my power pack cable and connector combination last night.
At a constant 15A and 20A the connectors didn’t even get warm, and even if they did heat up a bit the plastic construction on the inside seating the connector pins is made of something I can’t melt with a 450°C soldering iron.
The 18awg cable however will make a nice hand warmer. It got up to 50°C after 4mins at 15A, with a drop of 0.68v across the cable when cold, up to 0.74v at the 4 minute mark.
Was hoping for better.
Massive waste of energy right there, really need to find a more suitable cable, at this rate it might actually be more effecient to boost the voltage from the battery pack to something like 30v and then convert it back down to 7.4v in the torch. haha.

Having said that you have to be careful you get a decent XLR for power, I think mine must have been designed for speaker use or something else that matches or exceeds their 15A max rating. With plugs that aren’t universally used for high power distribution the construction can vary quite a bit. I have another XLR plug that has very thin contact tabs inside not really designed for soldering wires to. And the plastic is not as heat resistant either, wouldn’t be comfortable using that one here.

I can certainly think of a few uses for this light when it’s done :slight_smile:

If only! How I envy those that have a workshop these days :cowboy_hat_face:

The tail cap does not screw into the thread on the head (poetry :nerd_face: ) it is bigger! :frowning:

Oh, you see I wouldn’t have guessed that from the photos I’ve seen. Good to know, so it will require some machining to make this work. Thanks for the heads up!

Note to self: Always have flashlight host in hand before planning mod! :wink:

The cap is not that much bigger so it is a pain… hopefully it may be possible to get a cap from another light that would fit.

I do know a machinist who lives locally so getting something modified or a thread cut isn’t entirely out of the question, certainly finding parts that fit from other flashlights is an option but often I’ve struggled to find spares sold separately and buying a couple different flashlights just to use a part or two from them doesn’t feel right.
Not to mention that would leave me with another orphaned host that’ll require modding…vicious circle that! :slight_smile:

Getting a new end cap to exactly your design would be the way to go! but I hope the price would not be too high as you know the bloke. I want a double length battery tube for my shocker, but the quote I got was stupid money.

Must admit the few times I have needed parts for modding lights, I have been lucky to have found suitable donors from jumbles/charity shops and boot sales. So never felt that guilty about nicking bits off them.

Never quite understood the reluctance of light manufactures in selling spare parts.

Yeah, it’s a shame. I had no luck at all in finding spare parts for my Apex 5t6 and there’s quite a lot of those models out there. Even contacted a number of resellers to see if they had returned or broken parts/spares that I could buy. No deal. I suspect there’s just no incentive to make extra parts for customer service type situations and even factory seconds end up being used in making up a batch of second rate flashlights of varying quality that go out on sale.

For the BTU, at the moment i’m thinking more along the lines of shortening the front of the battey tube and machining a new thread inside so it can thread onto the head. Getting the spacing of the tailcap to the body just right once it’s fully seated into the head. Something like my last rendering, I quite like that form factor and it would still give me some limited space inside the body for whatever.
I dunno, I’ll have to put a lot of this aside until I have a play with the host and see what would make the most sense.

You should apply this for fenix flashlight design!

I didn’t know about the fenix competition, thanks.

Ok so I have a bit of progress to report, today I made the trigger clicky and it’s enclosure/mounting.

I haven’t cut the enclosure to the final assembly size/shape but the masking tape shows what the final thing will look like.
Way too risky to cut this now based on estimated measurements!

Inside it’s simply one of those standard 1.5A omten reverse clickies mounted on some random tailcap pcb I had lying around and trimmed down to fit inside the enclosure.
The enclosure I made from a 5v transformer/power supply casing which had a nice little ergonomic lip at the base. I cut this in half and sanded the two halves until I had the width that I needed. Then glued the two parts together, drilled and dremmeled out the hole for the switch boot and put it all together. There’s a backing plate mounted into a grooves inside the case and plenty of hotglue to ensure the switch doesn’t go anywhere.

The cable will run down inside the handle through the middle dovetail groove and the twisty part will take the rest of the cable down to the tailcap. Not certain how I’m going to run this into the tailcap just yet but probably just through it’s own port. Maybe with another connector if I get real fancy, for modularity and flexibility. :stuck_out_tongue:

Also just to be clear I won’t be running 15amps through this cable! It will just be the control switch for the drivers.:slight_smile:

And finally here’s some more renders of the model with the switch mounted. The blue line shows where the cable will be running.




Those MT-G2s are to scale btw! Huge buggers!! :party:

Cheers
Linus

Bit more planning stuff, this time on how I will be tackling the emitter mounting and how I’ll approach sinking some heat into that massive reflector.

Front view showing the noctigons in place and the crazy pattern of necessity for my copper spacers :).

The idea is to have the reflector back sitting flush on these copper spacers and sucking some heat off the pill.
Would love to be able to machine a nice copper spacer/gasket for this but I’ll have to make do with what I can find.
So far I’ve found some 15x15mm copper squares on ebay available in various thickness so I’ve ordered a bunch of different packs to combine and hopefully cover my spacing needs.
Going by my measurements and Noctigon/Cree datasheets I should need a spacer height of 2.3mm to just clear the top of the MT-G2 baseplates with the reflector. (The emitters pcbs themselves will probably be glued down)
So I’ve ordered 2mm, 1mm, 0.3mm and 2x 1.2mm sets of 10 spacers so I should be able to cover any distance that’s 2mm, 2.2mm —> 2.5mm in 0.1mm increments and even reach to 2.7mm if get some crazy tall noctigons for some reason. :stuck_out_tongue:

Of course they’re all separate little squares so once I’m happy with the fit I’ll probably try reflowing them together. Maybe in a kind of press or something that can be heated while keeping the components under good pressure to get a nice tight single piece copper disk. This sounds like a nightmare by I’ll give it a go :slight_smile:

In the end I just hope to be able to sink some heat into the massive bulk of the BTU reflector, because in stock form it looks like there is very little thermal pathway between it and the body/pill.

For the emitter wiring I’ll need to drill 6 holes through the pill surface to get the wires close enough to each pcb solder point. I figure drilling at an angle from the places shown on my model I should just about be able to drill through the thinner part of the pill and gain access to the driver cavity without going through too much solid sidewall.
In there I’ll have to see about adding some more thermal mass that’ll bolt to the bottom of the mcpcb mounting plate.
Depends on how much space I need for drivers and such.

For the drivers I’ll be running a separate set of 7135s/(slave driver) to each emitter so while the whole circuit will still be in parallel I should gain some per emitter regulation and avoid any issues with differing vF or resistances.

So that’s it, let me know what you guys think and if anyone has attempted something similar that I can learn from.
Especially with regard to those copper spacers and reflowing stuff like that together.
Cheers

Still here reading. Interesting.

Wow! I was thinking of getting a copper screw to replace the standard screw that goes into the reflector, thinking it will heat sink from the pill top to the reflector. Getting direct contact from the pill top to the reflector is a little beyond my capabilities, but I gave it some thought, wondering if even thermal pads stuck in there and compressed on contact would help, but don't think they are very efficient.

Still not sure how you will get the "perfect" spacing from those copper inserts to the reflector - you want the reflector sitting down to get the best output of the emitters for sure, not to mention how perfectly level they must be. Maybe you will use some quality thermal paste in there?

yup it may all go horribly wrong! :wink:

The biggest problem will be getting those copper pieces together and perfectly flat for sure. I imagine there will be a lot of cutting, sanding and cursing at whoever stenciled out the pieces in the first place.

If I get it just right the reflector will be fully seated on the spacers and the emitter domes will be as far into the reflectors as possible without themselves actually being pressed down on by the reflector rim. I want the pressure, if any to be on the solder points on the pcb. If I then find I need to move the reflector out a bit more because the focus of the emitters is wrong I should have the ability to do that by changing around or adding on some more of those copper spacers.

And yes there will definitely be a generous amount of thermal paste on all the contact surfaces. :slight_smile:

With regard to the copper screw, that’s a really good idea. I need to look at that, maybe I can find a high-copper brass bolt to replace the one that’s in there. Can’t hurt :slight_smile:
You wouldn’t happen to know the thread size and length of the stock bolt would you?

Cheers

Crap! Actually I worked on a Shocker mod'ed by someone else and they left the screw out! I found one that fit well, but think it was a US size. All I had to do was cut it down. Hhmm, can't recall the thread size... Was thinking of brass too, but like you said, high copper content would be better I assume.

Running these Shockers at 6A to each emitter does get warm pretty quick, so would think getting that reflector to do more heat sinking is good, but your amps have to be up there, because 4A is no problem with the pill and pill area.

No worries, I’ll take some measurements once I get the real thing apart.

Silicon Bronze seems like it would be a great option for a bolt. Not cheap though even if you can find the right size :slight_smile:

Bit of an update on the battery pack.

I received the lipos today and decided to get the battery pack assembled to a servicable/testable state.
I ended up going a slightly different route for the lipo packs, rather than the two Turnigy 5000mah 2s1p 20c softcase packs I chose to get two Turnigy 6000mah 2s2p hardcase packs with a 25c discharge rating.


Turnigy 2s2p 6000mah hardcase

I am actually not too keen on parallel wired cells in preassembled packs because I like being able to see directly how each cell is doing, but in this case it ended up being the best option.
This was mostly down to size and capacity, with the longer but thinner 5000mah packs I could have theoretically fit 4 in there but it would have been too tight to realistically do the wiring without soldering the packs in permanently. With the 6000mah 2s2p packs I have more space for connectors and wiring at the top while also filling up the vertical space fairly efficiently and getting some more capacity in there with less hassle (compared with two 5000mah packs).
The hardcase is also quite nice and means I don’t have to worry about potentially damaging the foil packages of the bare cells when jamming the lid shut. It’s quite a tight squeeze to get things closed up. :slight_smile:

Here’s the assembled pack as it currently stands, the two 2s 6000mah lipos connected up in parallel with deans t-connectors.
Above it are the twin relays also hooked up in parallel. They feature 6v coils, with a rating of 12Amps each and are triggered on by the master toggle switch on the outside of the pack.

Still to come is the temperature monitor/alarm and a circuit for automatic low voltage cutoff. Possibly also a short circuit detection, we’ll see.
But for now it’s ready to test.

Another difference to the last time I showed the pack is the much thicker coiled power cord. The 18awg cable I was using before just wasn’t up to the task and at 15A test currents it was wasting a stupid amount of energy through high resistance. This new cord is based on a 14awg copper stranded speaker cable and is performing much much better. The material of this speaker cable wasn’t keen to coil under heating so I had to shrink wrap it first them do the coiling and that worked out really well. It’s quite a stiff coil that likes to return to this position, much more so than my first attempt with the thinner cable.

It also weighs a heck of a lot more, but well… the lipos aren’t exactly light either! :slight_smile:

Speaking of which the total weight of the pack is now 1.36kg! Which means you’ll definitely notice its presence on the belt, and also means I need to beef up that belt clip to something more substantial.

Finally a couple more renders showing how I plan to run the switch wiring down the back of the light.

The parts are starting to trickle in now so I can’t wait to start assembling the final thing.

Cheers
Linus

I’m more excited for the outcome of this build more than any other build I’ve seen on here, bring it on!!!

Feeding Chain:
MEGA Shocker (this build)
Super Shocker
BTU Shocker

Did some battery pack run-in tests and here are the results.

They’ll do just fine at 15Amps, in fact that’s what I’m using to do these “gentle” run-in discharge cycles because it’s just a little above 1C load for each lipo. Basically nothing, which means there’s hardly any voltage sag.

In the chart I measured battery voltage based off the meter built into the pack and also took the voltage at the end of the coiled power cord using my DMM. This is important here because of the fairly substantial resistance losses in the cable and I need to know what voltage range is actually going to be available to the drivers.
You’ll see I still drop around half a volt across the length of the cable but it’s miles better than the 18awg wire I was using before, that was dropping over 1.5v in the same test scenario.

At half a volt I should be well within the working range of my target drive current for fairly long regulated runtimes even at ~5Amps per led.

I’m using the vF/I graph from the Mt-g2 torture test done by djozz to get an idea of where I need to be to get the results I’m after and if those graphs are reliable (which I’m sure they are) I should be well on track for >15A high and around 9000lumen emitter output.
Possibly with some source voltage headroom to go even higher for Turbo mode, 7Amps per emitter sounds entirely possible but probably not for very long.
I also need to keep driver and emitter wiring losses in mind but the cable is by far the biggest hurdle to overall performance.

In any case as long as my source voltage stays above 7v I should be able to achieve 5A per emitter quite comfortably and as this test shows, the voltage at the end of the cable is still 7.16v at 13mins into the test.

I didn’t want to discharge the batteries too far on this first test so I called it a day at 13mins, but I’ll do further discharge tests once I’ve cycled the packs a few more times and see how long I can maintain this voltage range before dropping below 7v.

RMM: There looks to be a place at the top of that list for an ULTRA Shocker, who’s on the case? :bigsmile:

Linus

Nice work Linus. One MTG-2 at 5 amps pumps heat like you would not believe. Cooling will be the biggest headache here. Keep it up. :slight_smile: