Even then unless you add some thermal compound, maybe silicone potting to increase thermal dissipation to the original driver/host I think the piggybacked linear driver will step down too fast, before the host is hot, depending on the output level.
See this graph with an SST-40 and 50mΩ of non driver stuff (springs, wires, cell), which is kind of a high number for four cells in parallel, even if they really low CDR.
2~3W is a lot for a board without thermal path to the host.
Hhmm, I got some high amp lights piggybacked. I always run 2-4 jumpers for ground to the piggybacked driver though - I'm thinking it helps, never proven though. Dunno - on some stock drivers, there isn't a whole of contact surface to the shell, so I' not sure the way I piggyback is much worse.
Here's an Amutorch X9, triple XHP50.2 3V hand burner" that I measured 30.7 amps with a GOLISI 26650, about 10,000 lumens at start:
With a couple other hand burners (
):
Ah yes but with DD FET there is not a lot of heat generated on the driver, just from the FET Rdson, traces, and 7135.
For a linear driver with the DAC, something like this :
.
Maybe with 0805 instead of 0603, and bigger case for the opamp, since the board is so big 
Dang, that's nice!
Damn, you guys are good haha. Very interesting stuff! Freeman- did you just design a BLF GT 3 volt board for this ??? Lol.
Yeah, but it didn’t take me too long, I just placed the components quickly, it’s pretty easy since there is a lot of space, I used 46mm but I’m not even sure what the actual size is ?
Something even better would be a buck driver, especially since the original carrier is 4S ? For high efficiency and full current for the whole battery range, but that’s more complicated of course.
46 mm is about perfect! I measured 45.6 mm for TA's driver for the GT90, and 45.75 mm for the TA MT09R driver and both fit loosely, so 46 mm is actually better.
The GT drivers has a big (wide) brass button while the MT09R driver has a spring. As long as you have a wide enough pad on the spring side, the brass button can be transferred.
I put a 12mm batt+ pad and the GND ring is 4mm wide, are these sizes okay ?
I can put it up on OshPark, though you’ll have to wait for Gchart’s DAC implementation.
You got the dims exactly matching - the 12 mm batt+ pad and the 4 mm GND ring - matches the TA GT90 driver perfectly. The MT09R driver is also 12 mm batt+ pad and a 3.5 mm GND ring.
Not to derail this fellas, but just stumbled across this…
https://m.aliexpress.com/item/1005003246180028.html
5050 3.14mm² assuming 2mm Ø “30W”
Nice it's available in 5000K and with a round surface - would that be like perfect for an aspheric? Hhhmmmmm. $11 qty 2 shipped.
Sounds too good to be true, but I bought two. Did you get them as well?
I ordered 2 bare and 1 mounted on a 20 mm 2 mm copper MCPCB.
They say 3000 lumens. 
JaredM, that led looks Great! i think, how does the round phosphor work? it says 8000ma max output? thats great! and 5000k?
Are these only good for aspherics?
Size comparison with the SFT40 and a CSLPM1
Should be pretty interesting if it meets its specifications.
I ordered two on 5000k
My order got canceled. Listing has changed to a new product. 
EDIT: There is something weird about the mobile version of the site. I’ll try clearing cache and what not and see if that changes anything, but the desktop version of the site still has the emitter listed. Ordered again, this time w/o a mcpcb. Fingers crossed!
I still see it here: https://www.aliexpress.com/item/1005003246180028.html?spm=a2g0s.12269583.0.0.1922f481t1weW1
My order not cancelled... yet
Previous post updated. Mobile site issue