The big brother of Nitecore UM2 with a little more charging current in the reserve for switching on.
The Nitecore UMS2 is visually indistinguishable from the UM2. However, the letter "S" reveals the slightly better equipment.  The Nitecore UMS2 has besides higher charging current of max. 3A on one slot or together 4A on two slots, battery status detection and indication after inserting the battery by "GOOD" or "POOR". 
 

The Nitecore UMS2 works with up to 3A on one slot.

Equipped with Quick Charge 2.0 processor, charging the batteries with a USB QC power adapter becomes unusually fast. Nitecore used the process that was originally developed for smartphones to optimise the power supply of the chargers. Besides the 2 bay Nitecore UM2 charger, the Nitecore UMS2 presented here was also equipped with QC interface.
 

Intelligent Universal Charger Nitecore UMS2 for Li-Ion, LiFePO4 and NiMh Batteries

The Nitecore UMS2 charger detects the battery type, determined battery condition, battery charge level and automatically determines the correct charging method. Charging of batteries up to a length of 77mm e.g. protected 20700/21700 batteries, automatic battery internal resistance detection, calculation of the charged capacity as well as Li-Ion battery reactivation are further useful additions.

Enables charging of Li-Ion, Ni-MH, Ni-Cd and LiFePO4 batteries. The charging system is optimised for IMR batteries and charges the batteries safely and gently. The LCD display shows the charging current, charging voltage, resistance and charging time for each charging slot. CE, FCC, ROHS and CEC certified.

The following battery types can be charged with the Nitecore UMS2 :

Li-Ion/LiFePO4:10440, 14500, 14650, 16500, 16340(RCR123), 16650, 17350, 17500, 17650, 17670, 17700, 18350, 18490,
18500, 18650, 18700, 20700, 21700, 22500, 25500, 26500, 26650, 26700 charging slot length 77mm.

Ni-MH/Ni-CD:AA, AAA, AAAA, C, D
Please note:  For rechargeable batteries with a diameter of 22 mm or more, max. two cells can be charged at the same time.

Nitecore UMS2 Product information:

• Intelligent 2 bay charger.
• Manual selectable charging current from 100mA - 3000mA per slot
• Integrated *QC 2.0 processor
• Total power in QC mode 4A (only with QC compatible accessories)
• Automatic battery internal resistance detection
• Charged capacity calculation
• Battery status detection
• USB connectivity for many power sources. (USB adapter, solar panel, power bank)
• Energy saving function
• Reactivation of deeply discharged batteries
• Time-controlled overcharge protection
• Two charging slots - can be used independently of each other
• Optimised, intelligent temperature monitoring
• Housing made of flame-retardant ABS plastic
• Intelligent reverse polarity and overcharge protection
• Microprocessor-controlled charging process that protects and monitors the batteries against overcharging
• Independent recognition of the battery type (Li-Ion, Ni-MH or Ni-Cd) LiFePo4 manually connectable
• The charging method (CC, CV or dV/dt) is automatically selected according to the detected battery type.
• Charging current is adapted to the detected state of charge of the battery

Test results: www.lygteInfo.de

Operating instructions: Nitecore UMS2.pdf

Scope of delivery: 1x NiteCore UMS2, 1x USB cable, manual German, English, Spanish, French, Russian, Italian and Romanian
USB power supply not included: 

Further notes on the UMS2 Charger from Nitecore.

For *Quick Charge charging mode (see "Technical specifications) a QC USB power supply is required. Suitable power supplies: Art. No.: 400617, 400622

Many newer smartphones are already supplied with QC power adapters.
Please make sure that you already have a QC power adapter before you order a new one.
For standard charging mode (see "Technical data), a 2.1V power adapter is sufficient. Suitable power supply units: Art. No.: 400609, 400610, 400611, 400616

*QC 2.0 (Wikipedia)

• Charging current QC mode:        3000mA x 1 (max); 2000mA x 2 (max) can be adjusted manually in 100mA steps
• Charging current standard mode: 2000mA x 1 (max); 1000mA x 2 (max) can be adjusted manually in 100mA steps.
• Input voltage: DC 5V/2A 9V/2A 18W (MAX)
• Output voltage: 4.35V ± 1% / 4.2 V ± 1 % / 3.7 V ± 1 % / 1.48 V ± 1 %
• Dimensions: 152 mm × 73 mm × 40 mm
• Weight: 148.3 g (without batteries and USB cable)
• Reverse polarity protection
• Automatic limit switch