QReciprocity42, per the below linked review on this site from when the TM28 was introduced Turbo sustained time varies with battery type used. Factory supplied batteries caused a large Turbo output drop at about 4 minutes.
Also another poster mentioned the combination of flood coverage and beam reach with the TM28’s four reflectors. The current Wurkkos TS32 with 12 flood LEDs and a fairly large central reflector and single LED spotlight, each mode separately controlled but capable of combined operation, is equally versatile I would think for about 1/4 the price as it is currently under $100 before sales taxes via 3 current offers on Amazon. It also offers color temperature LED options. Very close in size and weight to the TM28 too. Fenix also has their big brute light, the LR60R with similar capability but in a much larger and heavier light.
One reason I originally posted regarding the TM28 is that this is a light format that has virtually disappeared. I have multiple similar layout 4 reflector in a square arrangement soda can lights from about 10 years ago but this layout has become quite scarce currently. I presume that this is probably related to advancements in LED technology.
I don’t think the '20 has any real LVP, as it’s multi-fuel. It can take an 18650 or a pair of '123s as well, so unless it can “remember” what’s the initial starting voltage, and that’s assuming they’re topped up, the level(s) at which LVP kicks in would be different for each.
Don’t recall what’s the knee voltage for an XM-L, but I doubt it’s lower than 2.9V or so. So unless someone turns it on and leaves it on overnight, I don’t imagine any sane person wouldn’t notice it going dim to be almost unlit.
This is an interesting observation. The quad setup might have marginally better thermal performance (due to the 4 separate barrels having more surface area compared to a single barrel of combined diameter), but the cost in throw is too much–nowadays one can find a single LED (perhaps plus a ring of flooders as you pointed out with the Wurkkos), and cram all that in a single reflector, which throws much further than 4 separated reflectors with the same combined diameter, since the gaps between individual reflectors are eliminated.
I downloaded the TM28 and TM26 manuals for information. The TM26 manual specifically warns against using unprotected batteries so presumably the light does not have built in over discharge protection. The TM28 manual states that the light shuts down when the batteries reach 3V which sounds like it does have over discharge circuitry included. No warning given against using unprotected batteries. As both offer in situ battery charging they apparently have over charge protection though the listed charging time is 7 hours, quite slow by current standards.
Having been looking at the TM28 thanks to this thread I kind of want one now. Not that it would make any sense as I can get an L35 2.0 for a third of the price and even that’s more than I actually need. The TM28 just looks cool though.
A new TM28 just arrived with the optional battery pack NBP68HD. I could not resist as I also have the TM15 and TM26, both of which are compatible with the extended battery.
First observations:
As delivered batteries are not at all balanced. Charges from 35% to 55% so want to fully charge them with a external charger rather than in the light IMO. Otherwise I would expect internal to light balancing currents could be quite high with 4 batteries in parallel at quite different charge levels.
Other than markings the TM26 and TM28 appear identical. The TM28 is approved for unprotected batteries and includes a adapter for use of the shorter batteries. The 18650 battery tube still uses the sheet copper negative end connector at the bottom for connecting the 4 batteries and the design of this limits the accommodation for batteries shorter than Nitecore’s protected cells and for other protected cells longer than Nitecore’s. A set of protected Vapcell 3800 milliamp cells I bought are too long for the TM26/TM28 lights without modification.
The included charger is rated for 1 Amp at 12v even though the documentation for the light indicates that 2 amps is an acceptable input and decent electronics should limit current input to the acceptable level even with a higher current source. Nitecore has been shipping this 1 amp charger forever it seems, at least back to the TM15. With a correct charger and plug the extended battery pack can be charged at up to 4 amps at 12 volts per Nitecore. The included charger is going to take a minimum of 14 hours to fully charge the extended pack when fully discharged based on Nitecore’s claim of it taking 7 hours to charge the 4 batteries in the light maximum, presumably with the included charger.
Main switch is improved. More obvious differentiation between a half press and a full press. It feels like the full press spring has been stiffened to provide a clearer tactile difference between the two stages.