I think, my comment got lost:
The 2900s can lash out >7A before protection kicks in.
These are the cells from this thread: Discharge Capacity Tests on Soshine 18650 2900mAh Protected, cells courtesy of Louis Huang of T-mart. NCR-PF/Soshine graph added
They hold capacity even up to 5A continuous load!
Just ordered one tube, thank you.
I still do not quite understand how does this way work. So the heat from the emitter will soften the dome? And then what to do?
this flashlight has enough room for DD FET driver?
In post #2665 I listed a DD FET driver as part of my mods. I used a 17 mm driver - it's a little loose but can be secured fine with the retaining ring. I believe the stock driver is 19 mm, but not 100% sure. For height there's no problem - DD FET drivers are a low profile.
Thanks, i found your mod
Tell me pls, where I Can buy this powerful driver? 
With de-domed XP-G2 S2 will it be better thrower?
Ahhh - I build up my own from OSHPark bare PCB's and reflow the parts myself, write the firmware to my likings, and program the MCU (I used an Attiny25 in this case). I dunno where you are located but Richard (RMM) at MtnElectronics.com has the equivalent and lots of choices in firmware. Also may be out of stock, but the BLF A6 driver from BangGood.com is also similar.
For throw, of course you could de-dome the U4 1C and get at or near double the kcd. XP-G2's are a bit more finicky - first to get properly centered and don't know of any centering piece you can buy for that to fit a D80 reflector, then second: get lucky to get decent amount of amps from the XP-G2, but if you do, then yes: better throw than a de-domed U4 1C in theory.
This is a view of the driver used in my D80:
The stock driver is 20mm. How did you mount a 17mm? Not hardly support on the 20mm shelf?
I have a BLF A6DD driver to mod into the D80, but not enough shelf support for it as is. I confirm the retaining ring will secure and make contact properly. But not enough support for 17mm board IMO withot some sort of mod.
I replaced the stock driver with a MTN 20DD from MTN Electronics. It’s single sided so no problem there. It needed to be sanded down a little bit to 19mm. I removed the positive contact pad from the original driver and soldered it onto the new one. I found the new driver a little thicker than the original one so I sanded the retaining ring making it thinner to compensate for this. Just don’t take too much off the thread side because there isn’t much there to engage the threads to start with. It works great.
I may be confused (do that a lot lately), but pretty sure the 17mm driver just barely catches the edge but site a little lower, and the retaining ring does a good job to lock it down. I added the solder on the ground ring as shown above to ensure good contact.
Definitely took the pics of the exact driver I used in the D80, and didn't do anything else special to mount it. I tossed the brass button in favor of the wired spring. I'll check it again later to confirm. We could be talking fractions of an mm difference in diameter of drivers to work or not work. I don't have any BLF A6 drivers handy to check the dimensions.
Yep - I originally was gonna do the same thing onchiman did - sand down a 20 mm driver, so pretty sure it is made for a 19 mm driver.
Original driver is 18.9 mm dia.
But I am also using a 17 mm DD+1 driver (built from an MTN pcb).
It fits fine, but the pcb ground rings do not make contact. Three solder pads on the spring side, similar to TomE’s photo above does the job.
EDIT: Photo added:
Yeh, i was eyeballing it..hadn't removed the original D80 driver yet. So I didn't actually place it on the shelf as wires in way. Calipers confirm the 17mm contact ring will work alright.
I got mine today - it will not turn on with any combination of batteries… any idea?
does not turn on shunting the switch either.
Justin: oh boy, I'd take a first look at the LED: be sure the wires are connected good, no grounding. Unscrew the bezel and get out the lens and reflector.
Here's what I measured, varies from 18.95mm to 19.05mm or so:
Installed with the solder blobs showing a little:
Finally got my D80 5A!
I was pleasantly surprised by it’s small size and great finish. Does not look like a $21 light for sure. Will do some tests tonight.
Thanks everyone for this light.
Hi my flashlight has arrived but it will not turn on, I have tried several different batteries and bypassing the switch.
Are there any known problems that are easily fixed ?
I contacted gearbest and they want me to send them a photo showing the problem - how stupid is that a photo of a torch will not show much.
If you have any sized battery holder (with positive and neg. wires as test probes), remove the head and apply current directly to the driver board to see if led lights up.
Since you’ve ruled out the batteries and switch the only other things to look at would be the driver and led circuit. Do you have a multimeter? That makes things easier. But if you have some wire you can at least make sure that the led is working by applying power directly (briefly). + of battery to + of led and - to -. If you get light then itsit’s the driver or connection.
That’s pretty much standard protocol. My impression of their CSD is that they are very process driven. It doesn’t matter what the problem is, they need to fill out the check boxes in their claim form in order to process your request.
Just be thankful that they aren’t asking for a video.
You spoke too soon, just had a reply from Gearbest.
“Thank you for contacting us.
Could you please send us a video to show the problem?
Please contact us at any time if you require assistance.
We’re always keen to help in any way we can.
Best Regards
Hella ”
I have also tried power direct to driver board. so it looks like its the board or led.
Are there many problems with these or is just my bad luck, it might be easier to order another one than dealing with customer support ?
How do I explain in terms they understand that it does not work.