Nitecore UMS2 and UMS4 Charger Review

Official Specs
Key Features
Short Review
Long Review  
  Manual and Packaging
  What's Included
  Build Quality and Durability
  User Interface and Operation
  What I like
  What I don't like
Up Next


My first “real” cell charger was a Nitecore D4.  Nitecore came close to replacing it a while back with the SC4, but they’ve certainly done it with these new two chargers – the UMS2 and UMS4.  These chargers (most importantly?) fit 21700 cells, among other awesome features.  Read on!

Official Specs

Nitecore USM2
Nitecore USM4


The UMS2 is $28.95 at and the UMS4 is $38.95 there, too.

Key Features


  • Input DC 5V/2A 9V/2A
  • 18W (MAX)
  • Output voltage4.35V±1% / 4.2V±1% / 3.7V±1% / 1.48V±1%
  • Output current
    QC Mode: 3,000mA*1 (MAX) 2,000mA*2 (MAX)
    Standard Mode: 2,000mA*1 (MAX) 1,000mA*2 (MAX)
  • Compatible with
    IMR/Li-ion/LiFePO4: 10440, 14500, 14650, 16500, 16340(RCR123), 16650, 17350, 17500, 17650, 17670, 17700, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22500, 22650, 25500, 26500, 26650, 26700
    Ni-MH/Ni-Cd: AA, AAA, AAAA, C, D

USM4 is the same as above, but adds the following:

  • Input DC 5V/2A 9V/2A
  • Output current
    QC Mode: 3,000mA*1 (MAX) 2,000mA*2 (MAX) 1,000mA*4 (MAX)
    Standard Mode: 2,000mA*1 (MAX) 1,000mA*2 (MAX) 500mA*4 (MAX)

Short Review

I really like these chargers.  It’s not often that I say a charger can and will replace the SkyMC 3000 that I use on a daily basis, but the UMS4 has earned it’s place on my desk for certain.  And the UMS2 will make a great work charger!!

Long Review

Manual and Packaging

I didn’t actually receive packaging for either of these chargers.  I received them before they were released, and before packaging was made for them!  So I got a charger and a charge cable, nothing more.  I imagine official packaging will be slightly different than that. 😛

Still the manual is avaiable online, and linked below.


What’s Included

As stated above, all I got was the charger and cable.  I imagine the only other thing that will be included in the retail package would be a manual.



Build Quality and Durability

These are nice, sturdy chargers.  The build (and UI and just about everything) is the same for the chargers, so I’ll treat them same and say when there’s a difference.

The slides are very smooth.  The buttons are quite clicky (but not “quiet” clicky) – I could stand for some softpress buttons her.


The whole shape of both these chargers seems to intend for adequate cooling.  There are fins all over the body!


The contact points are typical.


The only port on either body is the input port, which is micro-USB.  That might draw some complaints, since being just micro-USB could limit the power, but it suits me because that means this will be a decent travel charger.


Same points as above for the UMS2!





Officially, the UMS2 is 152mm x 73mm x 40mm, and weights 157.7g.

The UMS4 is 159mm x 107mm x 41mm, and weighs 255.4g.





They’re certainly not the smallest chargers on the market, but they do support the longer 21700 cells, and both support charging two 26650 sized cells concurrently.


One reason I’m so fond of these chargers is that they have support for both Li-ion cells, and NiMH cells too.  My family uses a ton of both, so this means I can leave this charger around for anyone to use.

Below, see how (notably) a 21700 cell fits.


And AA LADDA cells work well, too.


The UMS2 has surprisingly big bays.  Probably even wider than the UMS4 (a bigger charger).


As I said above, power is provided to these chargers by micro-USB.  Both chargers have an 18W max, which some users will find limiting on the UMS4.

The UMS2 can do (at a maximum) 1 bay at 3A, or two bays at 2A.  The UMS4 can do (at a maximum) 1 bay at 3A, 2 bays at 2A each, or 4 bays at 1A each.  Four bays at 1A is respectable, particularly off micro-USB.  I didn’t test that specifically, but I did do a bit of testing.  The charts are hopefully pretty self-explanatory, but I’ll blurb a little.

UMS2, 1 bay in use, having manually selected 1A.


UMS2, 1 bay in use, default charge current.


UMS2, 2 bays in use, default charge current.


And here’s the UMS4, 1 bay in use, having manually selected 1A (a little after the run started).

One Bay One Cell 1A.png

And here’s the UMS4, 1 bay in use, default charger current.

One Bay One Cell 2A.png

And here’s the UMS4, 1 bay in use, default charger current for an AA NiMH cell.

One Bay One Cell Eneloop.png

And here’s the UMS4, 2 bays in use, default charger current.

Two Bay Two Cell 1A.png

I did test these chargers regarding operation from solar power.  As far as I can tell it, they work fine and will deal with brown outs successfully.  I’m not sure I yet understand fully what the actual requirements are, but this one seemed to do fine.

Also, it has to be said that the 3A charging capability of either of these devices depends on a QC 2.0 input.  If the charger is connected to a QC 2.0 port, then the charger will show “Quick Charge” and ‘unlock’ the 3A charge rate.  (I searched my house over and could not find a single plug that was QC compliant….  I wasn’t able to test QC charging.)

User Interface and Operation

There are two buttons for operating these chargers.  They don’t have to be used at all – the charger will happily do what needs to be done no matter what (appropriate) cell is placed in.


The left button is labeled “C”, and the right button is labeled “V.”  C cycles through charging status, and V cycles through a bunch of things:  Battery Health (Good or Poor), Internal Resistance, Charging Current, Battery Voltage, Charged Volume, and Charge Time.  Long pressing C will enter the Charging Setting (see more below) mode.  Long pressing V enters “Restoration Mode” which is only effective for over-discharged IMR cells (0-Voltage resurrection.)

In Charge Setting mode (accessed by long pressing C), the options are as follows (which is basically straight from the manual, but the manual describes it well, so…)

Short press C to switch to different setting parameters (Charging Current and Cut-Off Voltage).
In Charging Current selection:  Short press V to increase Charge current by 100mA
In Cut-Off Voltage selection: Short press V to select different battery type.

Long press V to access the maximum setting Charge current (that’s the flashlight equivalent of a “shortcut to turbo” – I love it.

Long pressing C saves whatever your settings are and exits to the main menu.  No action for 10s will do this, too.

Here are some UI screenshots showing the modes, generally.




What I like

  • 3A option!
  • 1A on 4 bays for the UMS4
  • UI is good
  • Screen is pretty, and pretty useful
  • Both fit 21700 cells
  • Both fit 2×26650 cells

What I don’t like

  • A USB out (ie powerbank capability) would be nice, possibly, but not really necessary
  • Some will see micro-USB as a fault, but since this charges at acceptable rates anyway, I don’t see this as a problem

Up Next

Continuing Nitecore week, I will have another Nitecore light tomorrow – one of the GTS series!


  • This item was provided by Nitecore for review.  I was not paid to write this review.
  • This content originally appeared at Have a look there for the best experience!
  • Whether or not I have a coupon for this charger, I do have a bunch of coupons!!  Have a look at my spreadsheet for those coupons.  Note I’ve upgraded that sheet so that now, you may subscribe and get notifications when the sheet is edited!!

Comments are closed.

Create a website or blog at

Up ↑

%d bloggers like this: