FENIX 18650 3500 mAh USB Rechargeable Battery

The Fenix 18650 is a 3500 mAh lithium-ion rechargeable battery with a built-in Micro-USB connector, designed for Fenix torches, headlamps, lanterns and bike lights that require the 18650 format. Before purchasing, check the battery compartment dimensions of your device: length and diameter vary between 18650 cells on the market and not every torch body accepts this version.

The 3500 mAh capacity extends runtime compared to standard-size cells rated at 2600–3000 mAh, meaning longer outings without recharging or carrying spare cells. The trade-off is a slightly larger footprint compared to lower-capacity cells: for this reason Fenix advises checking compatibility before use, particularly with torches that have a tight battery housing.

The built-in electronic protection circuit manages overcharge, over-discharge, short circuits and current spikes, while a gas vent valve activates under abnormal pressure. The absence of memory effect means the cell can be recharged at any point in its cycle without losing capacity over time. Direct Micro-USB charging on the cell itself is useful in the field, where a dedicated charger is not always available.

Key points

• A 3500 mAh capacity for longer runtime than standard-size 18650 cells, with fewer recharges during extended use.
• Built-in Micro-USB connector on the cell: charge directly from a power bank or USB charger with no need for a dedicated external charger.
• Electronic protection against overcharge, over-discharge, short circuits and current spikes; gas vent valve for passive safety.
• No memory effect: the cell can be partially recharged at any time without degrading capacity over time.
• Before use, verify dimensional compatibility with your device: not all Fenix torch bodies accept this cell.

In the box

• 1 x Fenix 18650 3500 mAh Li-ion battery with built-in Micro-USB connector