Nitecore UI1 Single-Slot Intelligent Lithium-ion Battery USB Charger for 18650
Quick take
The Nitecore UI1 is a palm-sized, single-slot USB charger for popular Li-ion/IMR cells including 18650 and 21700. It uses intelligent charging mode selection and shows charging status, making it convenient for travel and off-grid setups using 5V power sources. The main tradeoff is capacity, it charges one battery at a time, and larger cells may take hours to fill at its max 800mA output.
Pros and cons
Pros
- Single-slot USB charging rated up to 800mA for faster-than-trickle top-ups (5V input).
- Intelligent charging mode selection that adapts to compatible Li-ion/IMR battery types.
- Compact and lightweight design for travel, including an included battery/cable case.
- Works with a wide list of compatible cell sizes, including 18650 and 21700.
Cons
- Only one battery can charge at a time, not ideal for people who rotate multiple cells daily.
- Charging larger capacities can take hours at its 800mA maximum.
What buyers think
Buyer feedback emphasizes ease of use and convenience, especially for travel. Many mentions highlight that the charger is straightforward to operate and that the built-in indicator helps communicate charging status and battery level. Reviewers also describe reliable charging across common formats like 18650 and 21700, and they note the unit stays manageable in temperature during longer charging sessions. Overall, the evidence base is limited in detail, but the recurring themes are simple operation, dependable compatibility with popular Li-ion sizes, and practical portability.
Key features that matter for real-world charging
Compact, single-slot USB convenience
This is built around one job: charging one Li-ion/IMR cell at a time through a USB input. The design is small enough to pack easily, and it is intended for power sources like power banks, USB adapters, and similar 5V setups.
Intelligent charging mode selection
The charger is designed to automatically select an appropriate charging mode for compatible Li-ion/IMR batteries. Practically, that reduces the guesswork compared with basic chargers that treat all cells the same.
Status indicator for progress awareness
An on-unit power indicator provides real-time battery level and charging status, which is helpful when you are charging away from your desk and want confidence that things are progressing normally.
Designed for a broad set of battery sizes
It supports many common cylindrical Li-ion/IMR sizes, including 10340 through 26650 families, with specific mention of popular formats like 14500, 16340 (RCR123), 18650, 20700, and 21700.
Charging performance and limitations
The UI1 is rated for a maximum output current of 800mA, using a 5V/1A (5W) input. That is plenty for regular overnight or “top up later” charging, but it is not the fastest multi-slot bench experience. For larger-capacity cells, expect longer charge times, and plan your routine accordingly since the charger is limited to one battery at a time.
Pros and cons, translated into buying decisions
Who it’s best for
- People who want a portable USB charger for common flashlight and tool batteries (especially 18650 and 21700).
- Travel use cases where charging from a power bank or small 5V source is preferable to a wall-only charger.
- Buyers who only need to charge one battery at a time and value compact storage.
Who should consider a different charger
- If you routinely charge multiple cells together, a multi-slot model will save time.
- If you need consistently rapid charging for large batteries, the UI1’s 800mA ceiling may feel slow.
- If your battery types fall outside compatible Li-ion/IMR formats listed for the UI1, double-check compatibility before buying.
Price and availability
Pricing can vary by seller and region. If you are comparing, focus on the total value of what you need, including the included organizer case, your battery formats, and whether single-slot charging matches your routine. Buy on Amazon
Verdict
The Nitecore UI1 is a solid pick for anyone who wants a compact, intelligent USB charger for popular cylindrical Li-ion batteries like 18650 and 21700. It is easiest to recommend for travelers, flashlight users, and anyone charging one cell at a time. If you regularly charge multiple batteries simultaneously or you prioritize the shortest possible charge times, you will likely be happier with a multi-slot, higher-power alternative.
FAQ
Is the Nitecore UI1 a good charger for 18650 and 21700 batteries?
Yes, it is designed for common Li-ion/IMR cylindrical sizes, including 18650 and 21700. Just make sure your specific cell type matches the compatible Li-ion/IMR formats supported by the charger.
How many batteries can the UI1 charge at once?
The UI1 is a single-slot charger, so it charges one battery at a time.
What is the maximum charging current on the UI1?
It supports up to 800mA maximum charging current when powered by a 5V input.
Can I power the charger from a power bank or solar setup?
It uses a micro-USB input intended for multiple 5V power sources, including USB adapters and power reservoirs. If you are using solar, ensure the output is appropriate for the charger’s 5V input requirement.
Does the UI1 have a way to show charging status?
Yes, it includes a power indicator that provides real-time battery level and charging status.
Does it include anything besides the charger?
It is sold as a kit that includes the UI1 charger, a USB cable, and a battery/cable case.
Specifications
| Product Title | Nitecore UI1 Single-Slot Intelligent Lithium-ion Battery USB Charger for 18650, 18350, 20700, 21700, 16340, 14500 and More, and Organizer |
|---|---|
| Category | Electronics > Household Batteries, Chargers & Accessories > Battery Chargers |
| Brand | Nitecore |
| Manufacturer | NITECORE |
| Model Number | UI1 |
| Color | Black |
| Item Weight | 1.43 Ounces |
| Product Dimensions | 1.15"D x 4.82"W x 1.26"H |
| Output Voltage | 4.2 Volts (DC) |
| Input Voltage | 5 Volts |
| Current Rating | 0.8 Amps |
| Amperage | 0.8 Amps |
| Compatible Devices | Li-ion/IMR: 10340, 10350, 10440, 10500, 12340, 12500, 12650, 13450, 13500, 13650, 14430, 14500, 14650, 16500, 16340 (RCR123), 16650, 17350, 17500,17650, 17670, 18350, 18490, 18500, 18650, 20700, 21700, 22500, 22650, 25500, 26500, 26650 |
| Connector Type Used on Cable | micro-USB |
| Number of Ports | 1 |
| Item Dimensions D x W x H | 1.15"D x 4.82"W x 1.26"H |
| Specification Met | UL, CE |
| Mfr Part Number | UI1+ORG |
| Global Trade Identification Number | 06952506467242 |
| Unit Count | 1.0 Count |
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