Looks like your only other choice is the NiteCore UMS2, but I don't know much about that charger.
Thanks! I was hoping to find a universal charger that can also do large diameter batteries, like D batteries, as well as the ones I asked about.
Does anyone know if the Mi Boxer C4-12 would work? or the Vapcell S4 Plus? I don’t know why these companies that make chargers don’t post the maximum lengths.
Check the link I gave you.
You only have three choices (on that web page), the NiteCore chargers that I mentioned.
I’ve Nitecore UMS2 and UI1 for 21700 protected cell from Nitecore.
2 with micro USB
UMS2 ok for all NIMH (NiCd) so AA, AAA , AAAA, C and D cells, Li ion, IMR, LifePO4 also
UI1 only Li ion cells
The UM4 and the UMS4 are the same except the UMS4 charges at a higher rate? Same with the UM2 and the USM2?
From the Nitecore website, that looks to be the case.
Never trust company for lenght.
Only guy try to put cell inside can tell if it’s possible or not, and the link give by raccoon city
Technically i’ve Nitecore SC4 who can accept 21700 such as UMS2, but in fact SC4 only can 21700 unprotected, so no Nitecore 21700 protected contrary UMS2
I never really look for the difference 
But yes seem be only much power for UM compare to UMS
The MiBoxer will not. I just played with some different magnets and a 40T (70.2mm) and the max it can take comfortably is 72mm, maybe 73mm with a fiddle-factor. I think you could squeeze another 3mm out of it by modding the housing (removing plastic) but that’s about it. Actually it might be possible to just remove all the plastic at the negative end if the slider is long enough to move out further…haven’t had mine apart for a peek. Very nice charger, though.
Right now many of us are waiting for an extended bay charger that will handle 26800 cells and it sounds like maybe Xtar will come through eventually. There is a cheapie single bay unit Yoni-Q that will take it, but it’s a rather poor quality charger that you shouldn’t leave unattended (unless that aspect has recently improved). And there’s the slow magnetic universal chargers from Olight and Folomov (max out at around 700-800ma charge rate but they work).
If you haven’t seen HKJ’s wonderful test/review website, have a look there sometime. Here’s his index of tested chargers…always worth consulting before a purchase. You can click on the columns and sort them like excel. Sorting the slot length column lists just three chargers that go up to 79mm…all of them Nitecore, and the next group stopping at 77mm. I think when he measures slot length it’s kind of the max-comfortable length in order to not have to fiddle terribly and/or damage cell wrappers.
https://lygte-info.dk/info/roundCellChargerIndex%20UK.html
His battery tests and comparator graphs are outstanding…one of the best references available.
Welcome to BLF!
According to HKJ, the UMS4 might not accept your 77.47mm long cells.
HKJ says the UMS4 accepts 77mm cells.
Here’s the beginning of relevant info on that Yonii charger if you’re interested, but do read HKJ’s review on the similar one first….some product links for it in replies, too.
Odd. Nitecore’s website shows the dimension of the units are both the same. 159mm x 107mm x 41mm. For the UM4 and the UMS4
It would seem logical that the area where the batteries go would also be the same.
I am emailing Nitecore about this.
The evolution according to Nitecore O_0
Generally Nitecore 4 slot are “special”
Initially i’ve bought the SC4 for charge 3 26650 and 1 21700 at same time with different current
I don’t expect they twice the current by 2 on slot 1-3 and 2-4 and if one cell is full charge ,auto full power on the chanel remaining :person_facepalming:
“Never trust company for lenght.
Only guy try to put cell inside can tell if it’s possible or not, and the link give by raccoon city”
The best and only valid and real answer has been given above.
You might be on to something.
HKJ might have made a mistake.
It would be weird if the UMS2 and UMS4 accepted slightly different-sized cells.
I think he just rounded down. For the UMS4 in his review he says 77.8mm (and 79.8mm for the UM4, which is shown as 79 in the index).
https://lygte-info.dk/review/Review%20Charger%20Nitecore%20UM4%20UK.html
https://lygte-info.dk/review/Review%20Charger%20Nitecore%20UMS4%20UK.html
Good eye!
Thanks! 
That being said, I feel pretty confident if I get the UMS4.
My XTAR VC8 fits Thrunite and Imalent protected button top 21700's. Good charger. Nice features. No complaints.
From personal experience the vapcell s4+ will fit. I own both the batteries in question and the vapcell charger. I also trust what RC says implicitly. The Nitecore batteries are tricky. From my experience with two of them, they only charge well with the included usb cable. I have several usb-c cables that will charge anything else but no matter what the cables are incompatible with the Nitecore batteries. I intend never to buy another proprietary battery if I can avoid it
David
I measure with caliper 80,89. I will wait the 26800 (green) and i try to charge.