If this puppy is going to tip the scales at 8-lbs fully loaded with 18650’s then I definitely agree adding 1 even 2 more lbs to pack 21700’s inside would be well worth it.
I believe the DX80 is my heaviest light currently at 1.25kg or 2.76 lbs. (maybe my MF04 but it feels close to the DX80). I’ve gone for extended dog park visits with my DX80 which has 8x18650 with a massive aluminum PCB? (still learning… heat sink?) and after about 10 minutes I notice myself always trying to slide my hand up onto the head to distribute the very head-heavy weight better. After 30-40 minutes my forearms are definitely showing signs of a significant workout.
At almost 3x the weight here’s my humble take:
-with an abnormally large amount of weight located in the head I think 21700s would be a big improvement to help balance the beast. My MF04 is cool but it’s the most awkward light I’ve ever seen or imagined. Seriously, the only thing they could’ve done to make the MF04 more awkward would’ve been an 18350 shorty tube!
-I can’t imagine holding this with one hand for anything longer than 10-15 minutes so it would be a shoulder strap dedicated/supported light at all times for me
-With that much weight I would really push for a handle if that’s possible?
I’m seriously gobsmacked this thing is spec’ing out at 8 flippin pounds!! That’s probably heavier than my entire collection combined so far. When you’re setting records, adding some extra capacity couldn’t hurt
So has the production on the GT4 already started? If so, ignore the rest of this post
If not:
- I really don’t think weight should be the deciding factor. The GT4 is not your typical 1-cell EDC, but a WOW-light and will probably be used with a shoulder strap. Even if hand operated, I’m guessing most people would allow the extra weight to prolong that WOW factor, and not having the light output dip to averages levels because the batteries are drained
- Let’s assume the light again has a FET driver like the GT70, and at Turbo the 4x XHP70.2’s all run at 10A each, that is a drain of 40A on 4S1P, or 20A on 4S2P. According to test charts, the Vf should be around 13.26v for 10A, so each cell is only responsible for 3.315v. If we assume inefficiencies bring this up to 3.4v, according to HKJ’s charts, the Samsung INR18650-30Q 3000mAh can handle 20A for about 3mins, while the Vapcell INR21700 4200mAh (or similar) can handle 20A for about 6mins. That is a 100% increase in runtime for roughly a pound in weight increase.
- Going by the same charts, calculations and assumptions, High (50% PWM | 5A*4/2 | 12.3v) would yield:
— INR18650-30Q: 14mins
— INR21700: 21mins (+50%)
- Going by the same charts, calculations and assumptions, Medium (25% PWM | 2.5A*4/2 | 11.68v) would yield:
— INR18650-30Q: 32mins
— INR21700: 46mins (+44%)
- If I have to choose between carrying additional battery cariers in my pockets or an additional bag, and having the light a bit heavier, I choose bigger battery capacity.
The only reason why 21700’s shouldn’t be considered, should be if the size will make the light not hand “heldable”
(please don’t see the length of the post as a rant )
:person_facepalming: I didn’t realize that was a common perception! lol now I feel like I need your disclaimer above permanently inserted into my signature!
hehhe yea my biggest light is the olight x9r at under2kg or so, i was using that as reference to guess the gt4… didnt imagine it can weigh that much more wow… this thing can also be used as a defense weapon, i mean swing that light with some force can break some bones
This is actually my biggest issue with the 21700, it will indeed mean the light without the strap or a handle almost unbearable to use. Even with the 18650 tube and my large hands it is only comfortable to hold for a few minutes at a time.
All of these factors added together is why I have told lumintop the benefits both ways and basically left it in their hands to decide. I honestly can go either way on this one, I really have no opinion one way or the other.
Also thanks to Dale sending me a clamp meter the early prototype was pulling around 27A @ 12v with 30Q cells BUT that was with the sub-par resistance in a few areas that they are correcting for later versions. I expect 30a+ from the final version or higher with better cells. This is basically what I figured it would be when we started this. Although I think they will have to step down 1 wire size to make soldering easier (the prototype soldering overheated the driver and killed it due to how much heat it took to solder the wires), so that might counter the gains in the other areas so it is around the same.
Right now the light is just shy of 400w on turbo and hit LVP with 30Q cells at ~12 min IIRC. Although it would of gone a bit longer if not for the voltage drop, the cells were around 3.4V when I pulled them I think.
It peaked at ~88c? just laying on the table. Better then the GT70 which peaked at 92c IIRC with less then 1/3 the power.
Sadly the lack of information from lumintop means that is basically all I know and I can’t really mess with the light in case they need further testing.
Or a HD lanyard with some centrifugal force spinning it in circles would create a one handed flail complete with a strobing 20k lumen tornado that could be launched out of your hand! :smiling_imp:
lol doesn’t take advantage of the crenellated bezel though so back to the drawing board! :nerd_face:
Yeah, that is about what it would take for the MS18 to get close to the projected output levels but I will have to see tests to prove it is that much power before I believe it
At best that is around ~34A per cell which is really pushing things even for most 21700 cells and a driver that can handle all of that power. From experience, it can be done but is not easy and would take some real engineering to pull off.
I would love to get my hands on a sample for a review if they are looking for a reviewer…. Preferably one without glue.
I mean, look at runtime graphs for the MS12. It’s not using a buck or boost driver since brightness goes continuously down even at 10-15k lumens like the Thrunite TN36 Limited or their new 21700 lights.
:person_facepalming: 
