The Nitecore TM28 is now about 7 years old and maxes out at 6000 Lumens for a circa $400 list price. It does not have USB C charging capability and costs a bit more than the Acebeam X50 which is a similar size and weight light with circa 6.5x the output capability. The X50 also has high current USB charging versus a proprietary charger, can work as a power bank and at list price costs a bit less. The X50 also includes a handle which is a $35 option for the TM series of lights from Nitecore. Nitecore does at least offer an extended battery pack option, for a price. Also the Fenix LR60R is only a bit higher priced than the Nitecore, though a lot larger, and again has far more output than the TM28. And if you look at the current similar size offerings from Wukkos, Sofirn and some others the performance of the TM28 seems to be way behind the times. How can Nitecore justify their current price for the TM28 compared to the competition? What am I missing?
Having just watched Cheule’s review of the TM28 it looks like the output figures for the TM28 are sustained, in his testing it ran for a solid five minutes on turbo without much of a step-down and would probably have gone longer. In the outdoor testing it has a combination of both flood and throw that you don’t often see.
Comparing with the X50, the X50’s 6.5x output is not sustainable, its sustained output is around 5000 lumens. The X50 is also using a proprietary battery pack as opposed to the four 18650s in the TM28, which also includes an adaptor so that you can use flat-tops in it. The TM 28 also has a far superior battery indicator. Lastly, the X50 is a flood light, so it doesn’t throw anything like the TM28.
I can’t mind much in the way of reviews of the Fenix, but again it’s using a proprietary battery pack, which I consider a down-side. It is also, as you said, noticeably larger and it is more expensive.
The similar-sized Sofirn and Wurkkos lights are also flooders so not directly comparable and, again, if you look at actual sustained output aren’t out-performing the TM28.
I would say it was still relevant, we’ve reached a point where technology is now battling physics, there is simply a limit to how much sustained output you can get because of the heat and sustained output of similarly-sized lights tend not to be worlds apart.
Would not say obsolete, it still works as a light. There is much bigger competition these days. Dont forget the TM series was revolutionary and set the stage for the next five to ten years of light innovation. For example, the TM28 has an OLED display, there is still not light produced today like that (that I know of.)
Good points though the extended battery pack for Nitecore’s TM series is proprietary too and as light outputs reach fairly ridiculous levels the requirements for matched truly high current batteries probably encourages and possibly requires dedicated proprietary battery packs to reach specified performance levels with safety. As is the TM28 lists a requirement for using protected IMR batteries rated for 10 amps continuous discharge level minimum. The TM28 also uses a semi proprietary 1 amp at 12 volt charger for charging it’s batteries in situ in the light, a quite slow process compared to many more recent USB C charged lights. The extended pack is listed as accepting a 4A 12V charger but Nitecore USA does not list such a critter as available from them per their web site as far as I could determine.
With all of the junk 18650 cells being sold on Amazon and Ebay I can see more manufacturers going with either proprietary battery packs for high performance lights or being very specific about recommended minimum performance for the batteries for their lights and selling the lights with the recommended performance level batteries included as Nitecore does for the TM28.
Members of this group are overall far more knowledgeable about flashlight matters but the average purchaser and user is not. Just look at the Amazon glowing endorsements of cheap far eastern made lights claiming outputs from 200,000 to 2 million lumens when they are probably actually putting out 2000 lumens maximum from a single LED. 1Lumen has a good article on this problem and on Amazon it is virtually impossible anymore to find sellers of true high performance and quality 18650 or other Lithium Ion batteries. The cheap junk has driven out the quality items in that category.
By the way I have a TM26 bought years ago and do not much care for the user interface as trying to do half and full clicks on the operating button I find a bit of a PITA and the TM28 is very similar. I do wish though that more advance lights had the OLED display.
Never buy lights with proprietary batteries.
zoulas, the Fenix LR60R also has a OLED display. A much bigger brute of a light though. About the same size and weight as the Acebeam X75.
Not sure what your point is. So there are two lights with an OLED display? What does that prove.
You said you did not know of another. Actually Nitecore has multiple lights with OLED displays including 3 keychain models and their flat EDC models. A neat feature that almost no one else has adopted and yet it dates back to the TM26. However it looks to me like in some respects Nitecore design has failed to keep up with the competition. I could well be mistaken though. The marketplace will decide that.
You are being selective in what you read. Here is what I wrote again:
there is still not light produced today like that (that I know of.)
Once again, I do not know what point you are trying to make.
I’m gonna need a translator
Use Google.
Error, can’t detect language 
Cheule did remark that the head got burning hot, so maybe the decision to not step down at that point is not necessarily a win.
Comparing whether a light can sustain turbo is not a desirable metric because it penalizes lights that have the option to do bursts at extremely high output. If the X50 did not have any modes above 5000 lumens, which makes it a worse light, but helps it score better on the metric of sustaining turbo indefinitely, and beats the TM28.
I can’t find anywhere that it states that the TM28 requires protected batteries, but nor can I find reference to low voltage protection. The manual may clear that up but I’m not buying one to find out. 
Interestingly I couldn’t find the proprietary battery pack for sale either, which does rather support my point that I would prefer to be able to run it on 18650s. I agree that the charging is slow, I would probably prefer to remove the batteries and put them into a bay charger, but in fairness I’ve never really used speed of charging as a point to consider when buying a light.
Cheule didn’t actually measure the temperature though, and he did mention that it did fluctuate in brightness some, which would suggest active thermal management. Perception of “burning hot” is very subjective. 60º C is literally burning hot, but we don’t know how close to that the head got.
The value of a turbo mode is also subjective, personally I’m not really interested in how theoretically bright a light can go for a short burst, I want to know how bright can it be for a usefully sustained period. So for me the lack of a > 5000 lumen mode that only lasts a minute anyway doesn’t make the TM28 a worse light.
The third point is that the X50 and TM28 are not an apples to apples comparison because the X50 is a flood light and the TM28 provides throw and flood a bit like the L35 does. Which is better is going to depend on your use-case and the numbers become less relevant if the beam profile is just not right for what you want to use it for.
I presume that the TM28 needs protected batteries as that is what Nitecore ships with it per the write-up of the batteries on their web site. A 10 amp continuous discharge rated IMR cell. If not needed then they would not presumably have the protection circuitry in the batteries.
There are far better options today for around the same price (or less) that easily sustain twice the brightness (MS12 Mini, SR16). Even the Lumintop Mach 46950 sustains over 5000 Lumens for aeound $175.
As far as I’m aware all Nitecore batteries are protected. My MH20 came with one originally but it’ll run quite happily on unprotected batteries too.
Chris, have you checked the battery voltage when the light cuts off? That would indicate if the light has internal over discharge protection. In my collection I have an old light that takes 26650 batteries. It is without over discharge protection and has high leakage current that can way over discharge lithium ion batteries.
That is a good point and honestly, I haven’t. I only have a small number of batteries and swap them between my lights as needed, so lights not in use are stored empty and ones in use I keep an eye on the voltage. Because this is the way I do things I’ve never run a battery until it shuts off.
I’ll do some digging and see if I can find a reference to LVP for the MH20, owing to the aforementioned small number of batteries I don’t really want to kill one for science if it turns out that the light has no LVP.
EDIT - I’m being daft here. The TM28 includes an adaptor to allow you to use flat-top 18650s, and flat-top batteries are unprotected. The MH20 however remains an unanswered question for now.