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

Flashlight Modding and DIY Parts
38

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

39

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

40

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

41

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

42

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:

43

Oh I’m sure heat will be my biggest problem. I fully expect my turbo mode to be a short burst only mode. :slight_smile:

I’m beginning to realise just how much 100watts of heat is and how difficult it is to dissipate even on my substantial resistor bank. Had to bring in a 12cm fan to keep things in check for the test. :stuck_out_tongue:

44

What’s this!. A real life/non digital flashlight in this mod thread! Never thought I’d see the day :stuck_out_tongue:

The BTU host finally arrived along with most of the parts I needed for the handle. So I got stuck into assembling the handle and finalizing the trigger switch before putting it all together. I was really keen to see if this thing would actually fit as I had anticipated.

So far so good, and thanks to the 3d model no real nasty surprises.
Here is where it’s at right now. :slight_smile:

The handle is temporarily mounted to the battery tube using a two part barrel scope mount with picatinny rail top, thanks for this goes out to the inept Kaidomain shipping department who sent me this completely by mistake instead of a plastic reflector I had ordered. Thanks guys, it actually came in much handier than the reflector would have as the actual rail part that I plan to use is still in transit. :slight_smile:
Ultimately with the proper rail in place the handle will sit about 15mm lower than it currently is but other than that it’s very close to how I want it.
I’m still debating whether to mount that handle rail to the tailcap as in my renderings or directly to the battery tube. The latter would give me more options for a secure attachment while the tailcap option would probably make boring out the tube for 4x18650 cells easier. The tailcap is even less spacious that I expected and drilling two m4 holes to mount that rail may not be possible anyway so it could be an easy choice in the end. We’ll see.

-


For mounting the switch I cut the case down to size, added a metal plate to the top with m3 threaded hole and drilled a countersunk hole through the top handle rail to bolt it securely into place. Sounds easy and straightforward doesn’t it. :stuck_out_tongue: It really wasn’t and gave me all sorts of headaches but in the end I got it potted with epoxy and very securely mounted. :slight_smile:
Works well but I really hope the switch won’t fail anytime soon because getting it back out to replace it would be a nightmare…!


In any case the handle feels really good and offers a steady hold of the bulky light, the trigger switch is easily accessible by index finger and with this placement of the handle and the bare torch host the whole thing is also quite nicely balanced.
Really pleased with it so far and I think it looks pretty cool as well, it’s clearly cobbled together but still looks like it means business :slight_smile:


Still lots to do before I even think about the guts of the light. Next up is the tailcap and figuring out how best to mount the XLR socket inside. Should be fun :stuck_out_tongue:

Cheers
Linus

45

Wicked. Totally wicked.

J)

46

I hope those cable ties aren't your perma solution.

Going the full nine yards, you should be able to find a way to get some short metal tube (prob around half the length of the original battery holder), thread it and mount that handle with some bolts.

47

There’s no problem that can’t be solved by cable ties! :wink:

The whole handle mounting is totally temporary, like I said even the rail mount I’m currently using isn’t what I will end up with. It’s just a scope mount from Kaidomain that happened to arrive in the mail by accident and I put it to use since it had a short picatinny rail on top that I could easily mount my handle riser to for testing. Works surprisingly well though and gives me a chance to try out different handle mount configurations before I commit and start drilling into the BTU.

Ultimately I will be bolting a short, relatively flat picatinny rail onto the body of the light which I will then mount the handle riser to directly. Still not sure if I will try to attach this rail further back on the tailcap as I planned in my 3d models or if I will drill the bolt holes directly into the battery tube as in the current handle configuration.

Or… as you say I could use the current scope mount, ditch the temporary zip ties and figure out a better mounting for it that would be sturdy but also non destructive to the BTU body. I was thinking along he lines of replacing the zip ties with thin metal rods with threaded ends that I would bend around the battery tube/body and bolt/tension to the scope mount plates with a set of lock nuts.

Lots of options at the moment :slight_smile:

48

Through all the BTU threads/posts/pics every time I think to myself “that is a big light… and I need one.”

But that picture of you holding onto the handle put it more into perspective.

I did a double take and it made me remember this ridiculously large shoulder-able halogen spotlight I was given some 5-7 years ago. There isn’t really resemblance, seeing a flashlight with a handle just made me remember it.

49

hehe, yeah the BTU is a BIG light. It’s kind of silly really, first time I picked it up it felt like I had just grabbed a deliberately oversized prop from a movie or something. Something like Hellboy’s personal flashlight! :wink:

With a handle in this kind of “lantern” format it makes a bit more sense to me.

50

Definitely makes sense to me for sure. I have tiny hands; fingertips can’t touch when holding a D maglite. :stuck_out_tongue:

Your mod looks great btw, even in mock-up.

51

Very nice. Your mod is looking real good.

52

That looks awesome! Really cool stuff here!

53

Oh look there’s a baby flashlight on my flashlight!

Thanks again goes to kaidomain for this scope mount that I didn’t know I needed, had no idea how useful it could be for this build! hehe :slight_smile:

54

There’s no such thing as too much.

Now you need to mount 3 more handles to the btu and 6 or 7 rails on the bezel so you can do something truely effective. Like this, but in a flashlight:

:wink:

55

hehe :slight_smile:

56

Great job wut a monster!

57

Well, a small update in the grand scheme of things but I succeeded in flashing my first nanjg 105c driver with custom firmware today!
Took a fair bit of reading, fiddling with SOIC clips and hitting dead ends with eXtreme AVR Burner before I finally got things working with AVRDude.
I couldn’t have done it without the great wiki resources and threads offered by users of this forum so thanks a lot to all involved :slight_smile:

Being able to flash custom firmware will be super handy in getting the precise driver modes and operation I want in this flashlight. Not to mention any other light. I’m pleased I have that hurdle crossed.

Cheers