I’m not new to this product—I previously owned the older version with a micro USB connection. With this newer version, I can clearly notice that the charging speed is much faster.
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An intelligent four-bay charger that reads each cell, picks the right current and shows voltage, capacity and health while it works.

Load all four bays and the UMS4 charges every cell together, sharing its 4,000mA total output at up to 1,000mA each over a Quick Charge source. A full set of head-torch and flashlight cells goes from flat to ready in one session, with nothing waiting in a queue.
Each bay runs its own cycle, so a half-full 18650 and a flat 21700 each get exactly what they need and finish on their own schedule.

When one cell needs to be ready fast, put it in on its own and a single bay pushes up to 3,000mA, taking a 3,500mAh cell to about 80 percent in roughly 55 minutes. The cell you grab on the way out the door is charged before you have finished packing.
Add more cells and the charger balances current across the bays in use, so the rest of your set keeps topping up at the same time.

The LCD shows live charging current, voltage, charged capacity, internal resistance and elapsed time, plus the charging mode it has picked for each slot. A glance across the screen tells you how full your set is and whether any cell is past its best.
When you want to take charge yourself, set the charging current and cut-off voltage by hand for a particular cell. The data enthusiasts want is right on the panel.

The UMS4 reads each cell, identifies the chemistry and capacity, then selects the right voltage and one of three charging modes. It handles IMR, Li-ion, LiFePO4, Ni-MH and Ni-Cd cells from a 10440 up to a 26700, plus AA, AAA, AAAA, C and D.
That covers the cells in your flashlights, head torches, cameras and tools, so a single four-bay unit replaces a shelf of mismatched chargers.

The UMS4 draws its power over a single USB-C cable, so a wall adaptor, a power bank or a solar panel can all run it. On a camp trip or a long drive, charge a full set of cells from the same pack that tops up your phone.
It accepts a QC 2.0 input for full speed, and falls back gracefully to a standard USB supply when that is all you have.
All four bays charge together, so a full set of flashlight and head-torch cells is ready in one go. A basic charger handles one or two and makes you wait.
The LCD shows live current, voltage, capacity and internal resistance. A simple charger gives you a status light and no way to spot a tired cell.
IMR, Li-ion, LiFePO4, Ni-MH and Ni-Cd from 10440 to 26700 and AA to D, all detected automatically. Most basic chargers stick to one or two sizes.
Reverse polarity, short circuit, overtime cut-off and temperature regulation keep an unattended charge safe. A cheap charger often has none of these.

A built-in temperature regulation system watches the heat and keeps the charge stable, while reverse-polarity, short-circuit and overtime protection guard against the usual mistakes. Leave a full set of cells charging while you sleep or work, and the UMS4 holds them safe.
Over-discharged cells get an activation step, and Li-ion restoration can bring a flat cell back, giving older batteries another run instead of the bin.

The shell is moulded from fire-retardant PC, so it stands up to the rough and tumble of a kit bag and to the demands of charging four cells at once. Cooling fins along the body draw heat away from the cells for a steady charge.
At 255.4g and 159mm long, it has the bench presence of a proper four-bay unit while still travelling well in a pack.
Charge a full set of 18650 or 21700 cells together so your lights, head torches and tools are all ready at once.
One bench unit for the whole drawer, from camera 16340s to AA and D cells, each detected and charged to the right voltage.
Run it from a power bank or solar panel over USB-C, and refill a full set of cells wherever the trip takes you.
Set the current and cut-off voltage by hand, and read internal resistance to track how each cell is ageing.
| TYPE | SIZES | WORKS |
| 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 | Yes |
| Ni-MH / Ni-Cd | AA, AAA, AAAA, C, D | Yes |
| Charging bays | 4 (independent) |
| Input | DC 5V/2A, 12V/1.5A, 18W (MAX), QC 2.0 |
| Output voltage | 4.35V / 4.2V / 3.7V / 1.48V (±1%) |
| Output current (QC) | 3,000mA x1, 2,000mA x2, 1,000mA x4 (MAX) |
| Output current (standard) | 2,000mA x1, 1,000mA x2, 500mA x4 (MAX) |
| Total max output | 4,000mA |
| Charging modes | CC, CV and -dV/dt (auto) |
| Display | LCD: current, voltage, capacity, resistance, time |
| Body material | Fire-retardant PC |
| Dimensions | 159mm x 107mm x 41mm (6.26" x 4.21" x 1.61") |
| Weight | 255.4g (9.01 oz), cable not included |
| Download Instruction Manual (PDF) | |
If your cells are IMR, Li-ion, LiFePO4, Ni-MH or Ni-Cd, the answer is almost certainly yes. The UMS4 takes round Li-ion cells from a tiny 10440 up to a 26700, which covers 18650 and 21700, and it also charges AA, AAA, AAAA, C and D. It detects the chemistry and capacity on its own and sets the right voltage for each slot.
The 3,000mA figure is the maximum for a single bay on its own. With all four bays loaded the charger shares its 4,000mA total output, giving up to 1,000mA to each cell over a Quick Charge source. To reach the full 3,000mA, charge one cell at a time.
The LCD reports live charging current, battery voltage, charged capacity, internal resistance, elapsed time and the charging mode in use. Internal resistance is a useful health check, since a cell that reads high is on its way out. You can also set the current and cut-off voltage by hand when you want manual control.

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Try it for 60 days. If it’s not right for you, send it back.
We stand behind our gear. If you’re not happy with your purchase, just return the full package within 60 days and we’ll issue a full refund—no fuss, no forms, no hoops to jump through.
Spend $99 or more today, and we'll automatically include a limited-edition Glow-in-the-Dark Ember Shard Whistle when packing your order.
Charge it quickly under sunlight or your flashlight, and enjoy its subtle glow throughout the night—perfect for marking gear, emergency kits, or attaching to your bag.
Limited quantities. These will be swapped (at our discretion) to other gift items if shards are unavailable.
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