Efest Slim K2 Two-Slot Battery Charger

Slim K2: monitor each battery separately

The Efest Slim K2 charger has two independent slots. You can insert one battery or use both slots at the same time. LED indicators let you follow the charge of each cell.

Current and supported sizes

Charging can reach 1 A per slot with a suitable power supply. This current applies to the battery inside the charger; it does not, on its own, describe the requirements of the USB source. Follow the power input information marked on the Slim K2 and in its manual.

Supported sizes include 18650, 20700 and 26650. Also check the battery chemistry and its permitted charging current: a compatible size does not replace these checks.

Inserting and removing batteries

Inspect the insulating wrap before placing each cell in a slot, then follow the polarity markings. Do not insert a battery with a torn wrap. Keep the contacts clean and use the charger on a stable, dry surface without covering it.

When the indicators show that charging is complete, disconnect the power supply before removing the batteries, as instructed in the Efest manual.