I do not know the specifics of the
Nitecore TM06S.
In general, however, CR123A batteries are of little use in high-power flashlights. That is because those batteries are typically rated by their manufacturers for a maximum continuous discharge current of 1.5 amps. Many flashlights now pull more than that on their highest modes.
CR123A batteries were great when SureFire was putting them in low-power incandescent flashlights in the 1990s. Today, however, many modern LED flashlights demand more than CR123A can provide.
CR123A batteries still have an important place in modern flashlights. Their small size, long storage life, and good operating characteristics at extreme temperatures make them an excellent choice for little-used, emergency flashlights, as well as for other uses.
As is noted above, there is sometimes a sacrifice that a designer must make to achieve compatibility with CR123A. More and more, of late, designers are choosing not to do that.
The
Nitecore MH20 is an example of a flashlight that can run on either 1x18650 or 2xCR123A. When, however, selfbuilt performed runtime testing of the MH20 with CR123A batteries, the high current draw tripped the PTC protection in his batteries.
Here is what selfbuilt wrote when I asked him about it:
Your runtime charts and accompanying explanation suggest that the CR123A batteries have been driven to their limit. Huge drops in output are not caused by intelligent flashlight circuits. Instead the batteries' PTC has kicked in, forcing reduced current flow. Is this a good flashlight design?
Yes, I find it a source of concern to see PTC features kick-in on CR123A cells. I have certainly see a lot of this over the years in testing (especially common on 4xCR123A lights). Examining the cells, you can sometimes see clear evidence of damage in the wrappers around the PTC. Invariably, the worse-affected cell is the one closest to the head (where most of the heat is concentrated).
It's fundamentally a problem of how heavily-driven lights are now on max, in general (i.e., not specific to Nitecore - or Olight, or Thunite, etc, etc.). Multi-cell CR123A setups often don't seem suitable for sustained runtimes at max levels - even in lights with thermal regulation (which is designed to protect the circuit, not the battery). But of course, that's based again on made-in-the-USA CR123A calibration levels for PTCs. With made-in-China cells, you would probably almost never see that runtime pattern.
Ultimately, I would encourage people to use care when considering multi-cell CR123A use on any highly-driven light.
[Emphasis added.]
If you limit output in a 2xCR123A flashlight to somewhere around 650 or 700 lumens, you should be okay. That may mean staying away from the turbo and high modes.