TM16 emitter swap (XM-L2 -> XHP50) done - now funny lumens

Hey guys!

i swapped the LEDs from XM-L2 to XHP50 in my TM16 and now have a funny behaviour....

the driver is still stock

i modyfied the stock NON-DTP aluminium MCPCB from 4S to 2S2P

used better thermal paste

all levels act similar - only high gives a bit more Lumens....

but on Turbo the lumens go up and down fast and settles at around 4200 Lumen (starting to heatsag then...)

same thing with and without the NTC connected

XM-L2 3 Lm 299 Lm 695 Lm 1840 Lm 3840 Lm
XHP 50 3 Lm 295 Lm 690 Lm 1920 Lm 4680~3600 Lm
amps @ XHP50 0,003 A 0,175 A 0,413 A 1,21 A 3,41 A

have anyone seen a behavoiur like that?

next steps: sourcing copper DTP boards / driver push

What the beam profile m8? the driver could suffer the different leds dynamic resistance, with those 4 it should be very low

i did not make beamshots - but at 2m there where no crosses or doughnuts…

can you explain that?

Here you are

Or maybe

Those oscillations on turbo are prolly caused by that .

Thanks for sharing those issues btw, since i got my tm16 i also think of modding it…or the TK75 2015, i still cant decide which is better light for XHP50 modding

i was thinking on a driver change - but i really like the 2 sidestitch-UI from nitecore…

(especially having a SD75 in the other hand…)

-> since i am no “electronican” - what could i do?
(i ordered 4 noctigons to put the LEDs on copper….)


Did you have further success with this light? I was thinking of doing the same thing, but I thought I would have to completely change out the driver.

i am waiting for four noctigon to go full with the stock driver….

Yes the thread is a little old. Have you considered just changing from 4 series XM-L2’s to 4 parallel XHP35’s. I read your review on it’s driver and came up with this from your numbers. Series the theoretical of the XM-L2 U2 is just over 950 lumens. Divide by 4 for the parallel XHP35 F2 HD and the theoretical is just over 1220 lumens. Needed forward voltage is 13.24 for the XM-L, only 12.23 for the XHP35. That’s without any driver mods and 2.5 less watts used.

nice calculation!

maybe i try that some time :wink:


looking at your review (review: nitecore TM16 - final!), the driver uses MP2380 step down converter (
I see only voltage control (not current) in this converter. So probably you just need to adjust the voltage devider to higher voltage?
It seems to me that R207 and R206 (precise resistors 100 and 150Ohm , may be i’m wrong) are the part of voltage divider, may be there are some more resistors (I dont see those on pictures from review).

I’m planning to mod my TM16GT from 4x XP-L HI in series to 4x XHP-35 HI in parallel.

Took some measurements and the VF looks pretty convincing:
Moon: 10.3v
Low: 10.8v
Med: 11.3v
High: 11.8v
Turbo: 12.5v

According to XHP-35 spec sheet Vf at 1A should be around 12.3V, and since the stock driver won’t drive the LED at 1A each, I guess we’re fine.

The reflector opening is exactly 9mm and the convoy L2 spacer fits perfectly, although too tall for proper focusing. I ordered some custom spacer from Hoop. Stock MCPCB will not work here, noctigon should be 20mm to clear for the reflector base and they have to be cut in half near the center using a dremel to fit 4 of them.

Then the 4x XHP35 HI will be wired parallel with 22AWG wire. Anyone know if the NTC resistor is required for the driver to work?

The XHP-35 HI is available on LEDDNA & ebay but the bin is unknown… well I don’t think I’ve got many choices neither for CW tint.

What do you guys say? will this mod work?

try and glue the NTC between the noctigons (driver works without NTC - but i do not know what happens)

for the LEDs you can contact (user welight) and ask to send in an envelope maybe to cut shipping limits

I sure hope so, I think I was the one who put the numbers out. I did do the numbers with top bin High Density XHP35’s at a projected 0.625 amps. It was a guess from your readings on your website review. 1220 lumens best bin HD/1000 lumens best bin HI. Those number don’t quit take into account that your needed voltage will be slightly lower.

will34, did you ever go through with the XHP35s on your TM16GT? I saw my 16GT at the back of my cupboard, and realized I never use it. XHP35 HIs were the first thing that came to my mind.