Nitecore UM2: our full review

Two bays, a large LCD screen that shows down to each cell's health status, and USB charging that climbs to 3A with the right adapter: the UM2 carries the UMS4's formula into a compact two-cell version.

Our rating
4.1/5
Safety and protections: 4.0 out of 5 (weighting 20%)Safety4.0Build and endurance: 4.0 out of 5 (weighting 15%)Build4.0Format and chemistry compatibility: 4.4 out of 5 (weighting 25%)Compatibility4.4Charging precision: 3.8 out of 5 (weighting 25%)Precision3.8Display and control: 4.3 out of 5 (weighting 15%)Display4.3

How is this rating calculated?

Nitecore UM2 two-bay charger with LCD screen

The essentials

The UM2 delivers on the promise of a serious, readable two-cell charger: a large LCD screen shows voltage, current, capacity charged, cell type, and health status for each bay, a richness of information rare in this format. Its compatibility covers Li-ion, LiFePO4, and NiMH from 10440 to 26650, with automatic chemistry detection. Speed, though, depends entirely on the power source: without a Quick Charge adapter, charging stays slow, and there's no clean shutdown without unplugging the cable. As a compact charger to slip into a bag, at this price it's hard to fault.

Strengths

  • Complete LCD screen: voltage, current, capacity charged, cell type, and health status per bay
  • Very broad compatibility: Li-ion, LiFePO4, and NiMH/NiCd, from 10440 to 26650, plus AA and AAA
  • Up to 3A on one occupied bay with a Quick Charge adapter, a real time saver
  • Compact, lightweight format (148g), easy to slip into a bag or drawer
  • Automatic detection of the inserted chemistry, no manual setting required

Limitations

  • Charging speed depends entirely on a Quick Charge adapter upstream, without it charging is slow
  • No clean shutdown of the unit without unplugging the power cable
  • Only two bays, versus four or eight on other models in the lineup
  • One-year manufacturer warranty only, shorter than some other chargers from the same brand
  • No internal resistance testing function, unlike the Xtar VC4SL
Nitecore UM2 Charger: see the full details and price →

The compact two-cell companion

The Nitecore UM2 is a smart two-bay charger, built for flashlight and rechargeable cell users who want a compact unit without sacrificing tracking functions. It plugs in via a simple USB-C cable.

2
Independent bays
3 A
Max current (1 cell, with QC)
148 g
Weight

From 10440 to 26650, Li-ion, LiFePO4, and NiMH

Its compatibility is very versatile for such a compact format: Li-ion, IMR, and LiFePO4 cells from 10440 to 26650, including 18650, 20700, and 21700, as well as NiMH batteries in AA and AAA sizes. Both bays are independent, so you can charge two cells of different types or sizes at once.

A surprisingly complete LCD screen

The LCD screen shows in real time the voltage, current, capacity charged, cell type, cutoff voltage, and health status of the cell, a far richer readout than simple LED indicators, rare in such a compact and affordable format.

Up to 3A, but only with the right adapter

Speed depends entirely on the power source. Plugged into a Quick Charge adapter, the UM2 delivers up to 3A on a single bay, or 1.5A per bay when both are occupied.

Worth knowing: with a standard USB supply lacking Quick Charge, charging speed stays noticeably slower. Another practical point: the unit stays powered as long as it's plugged in, with no clean automatic shutdown.

Standard protections, a shorter warranty

The UM2 protects against reverse polarity and short circuits, and stops charging at the end of each cycle. The manufacturer warranty stays at one year, shorter than some other Nitecore chargers or rivals in the lineup.

Who the UM2 is for

This charger suits anyone wanting a compact, reliable model for two cells of different types, with precise tracking without needing a deep-analysis screen. To charge more than two cells at once, the Nitecore UMS4 with four bays from the same lineup remains preferable. For internal resistance measurement, the Xtar VC4SL goes further.

The rating in detail

Our rating
4.1/5
Actual charging current not measured
Battery compatibility not measured
Safety and protections 4.0
Build and endurance 4.0
Cables and connectors not measured
Actually delivered power not measured
Multi-port power sharing not measured
Protocol compatibility not measured
Size and technology not measured
Format and chemistry compatibility 4.4
Charging precision 3.8
Display and control 4.3
Nitecore UM2 Charger: see the full details and price →

The product and its alternatives

Nitecore UM2 Charger

Nitecore UM2 Charger

$17.78 (9)

A compact two-bay charger with a large LCD screen: the Nitecore UM2 recharges over USB at up to 3A and shows voltage, current, capacity and health for each cell.

View product
Nitecore UMS4 Charger

Nitecore UMS4 Charger

See price (20)

The four-bay big brother of the UM2: the Nitecore UMS4 charges four cells at once over USB, up to 3A per bay, with a large and very complete LCD screen.

View product
Xtar VC4SL Charger

Xtar VC4SL Charger

See price (10)

A four-bay charger with an LCD screen and USB-C: the Xtar VC4SL shows voltage, current, capacity and internal resistance, and charges at up to 3A on one bay.

View product

Frequently asked questions

Li-ion, IMR, and LiFePO4 cells from 10440 to 26650 (18650, 20700, 21700, 26650...) as well as NiMH batteries in AA and AAA sizes. It automatically detects the chemistry of each inserted cell.

Plugged into a Quick Charge (QC) adapter, it delivers up to 3A on a single bay, or 1.5A per bay when both are occupied. With a standard USB supply, charging is slower.

Its LCD screen shows in real time the voltage, charging current, capacity charged, cell type, cutoff voltage, and health status of each cell.

Charging stops automatically at the end of each cycle, but the unit stays powered as long as it's plugged in. You need to unplug the cable to fully turn it off.