Xtar 18650 3500mAh USB-C
The 18650 battery that recharges like a smartphone: built-in USB-C port, 3500mAh and 10A continuous discharge, no dedicated charger required.
Characteristics
- Capacity / Voltage: 3500mAh / 3.6V
- Charging: Built-in USB-C, 5V/2A, ≈2h50
- Continuous discharge: Up to 10A
- Recharges via USB-C, no dedicated charger needed
Detailed overview: Xtar 18650 USB-C rechargeable battery
The Xtar 18650 3500mAh USB-C belongs to a new generation of lithium-ion cells that solve a real hassle: charging. Instead of requiring a separate dedicated charger, this 18650 has its own USB-C port built into the negative terminal. A simple USB-C cable, the same one used for a phone or laptop, is enough to charge it directly, in around 2h50 with a 5V/2A power source.
On performance, it offers a nominal capacity of 3500mAh (3325mAh minimum guaranteed) at a nominal voltage of 3.6V, and can deliver up to 10A continuous discharge. Enough to power demanding torches and headlamps, cameras, some power tools and DIY electronics built around the 18650 format. Xtar rates it for over 500 charge/discharge cycles before any noticeable capacity drop.
This battery is protected: a built-in circuit (BMS) constantly monitors voltage and cuts power in case of overcharge, over-discharge or short-circuit, a safeguard missing from bare cells. A status LED turns red while charging and green once full. It also tolerates a wide operating temperature range, from -20 °C to 60 °C.
The trade-off for this integration: with its USB-C port and protection circuit, the cell measures around 70.3mm long (versus 65mm for a bare 18650) and weighs about 53g. This slightly longer format fits the vast majority of protected-cell torches, but it's worth checking on devices with tight tolerances, particularly some e-cigarettes, for which this battery isn't recommended. Sold as a single unit.
For anyone already running several 18650-format devices (torches, backup chargers, power tools), the promise is simple: never hunt for a specific charger again, and recharge directly from a power bank, a USB wall port or a computer, just like any other everyday device.
Comparison
Several 18650 cells compete with the Xtar 18650 3500mAh USB-C for searches like "USB-C 18650" or "best protected 18650 battery": the Panasonic NCR18650B, the format's long-standing reference in unprotected Flat Top form; the Keeppower 18650 3500mAh, a classic PCB-protected cell; and the Fenix ARB-L18-3500U, the catalogue's other cable-rechargeable 18650, but via micro-USB. Here's how the Xtar compares against these three alternatives.
| Criterion | Xtar 18650 USB-C | Panasonic NCR18650B | Keeppower 18650 3500mAh | Fenix ARB-L18-3500U |
|---|---|---|---|---|
| Capacity | 3500mAh | 3400mAh | 3500mAh (min. 3350mAh) | 3500mAh |
| Charging | Built-in USB-C, direct | External dedicated charger | External dedicated charger | Built-in micro-USB, direct |
| Built-in protection | Yes (BMS) | No (bare cell) | Yes (PCB) | Yes (multiple) |
| Charge indicator | Yes (red/green LED) | None | None | Yes (LED) |
| Observed price | £16.65 | £17.60 | £12.72 | £25.15 |
In short, the Xtar 18650 USB-C matches the Keeppower's capacity while offering the same direct-charging simplicity as the Fenix, all at a competitive price among the four. The Panasonic NCR18650B keeps the edge for anyone who prefers a bare, unprotected cell that's shorter and fits the widest range of devices, but for charging without pulling out a dedicated charger, the Xtar remains the most versatile choice.
Our tester's review: Pierre Freysinger
We tested the Xtar 18650 3500mAh USB-C in a hiking headlamp and an old backup charger that had only ever known AA batteries. The real comfort is charging it straight from the power bank already in the bag, no need to pack a separate 18650 charger: under 3 hours and it's ready again. The built-in protection circuit is also reassuring for unattended outdoor use, with the LED switching from red to green once full. One small downside: at 70mm it is slightly longer than a standard 18650 and won't fit every battery compartment with tight tolerances, worth checking before buying. It isn't designed for e-cigarettes either. But for torches, power tools or DIY electronics, it's a genuine everyday simplification without sacrificing safety.
Frequently asked questions: Xtar 18650 USB-C rechargeable battery
It has its own USB-C port built into the negative terminal: a simple USB-C cable is all you need, no dedicated charger required. A full charge takes around 2h50 with a 5V/2A power source.
Yes, a built-in protection circuit (BMS) guards it against overcharge, over-discharge and short-circuit, a safeguard missing from classic bare 18650 cells.
Up to 10A continuous discharge, making it compatible with most powerful torches and headlamps on the market.
In the vast majority of cases yes, but its USB-C port and protection circuit make it slightly longer (around 70mm versus 65mm for a bare 18650): check your device's tolerance, especially if it requires a standard protected cell.
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Published on 05/09/2026