Efest K4 Slim USB-C Battery Charger

The Efest K4 Slim provides fast USB-C charging for up to four battery cells and is compatible with various battery sizes.

Compatible with Lithium IMR 3.6V/3.7V Batteries:
10440 | 14500 | 16340 | 17340
18650 | 18490 | 18500 | 18650
26500 | 26650 | 20700 | 21700

The Slim K4 will charge your battery cells a few seconds after installation. The indicator shows blue when in standby mode or when the batteries are fully charged. The indicator will show white when the battery cells are set.

Auto-detect charging current: 1 x 1.0A / 2 x 1.0A / 3 x 0.5A / 4 x 0.5A
Safe charging mode: CC & CV | Safe and convenient USB charger (5V 2A)
Monitors and charges each slot independently | Low voltage smart activation recovery function
Super lightweight and portable

The piano wire-made spring ensures smooth gliding of each slot when installing and removing batteries. The Slim K4 is designed with a steel cathode, low resistance and hard chromium plating to achieve a more accurate charging voltage.

Type-C USB helps to reduce the heat of the port effectively.

The built-in intelligent chip comes with six protections.
Short circuit protection | Automatic overcharging protection
Automatic over-discharge protection | Reverse polarity protection
0V activation recovery function | Hardware and software double protection.

Global insurance technical support with FCC, CE, and RoHS certification

Please see our comprehensive guide to battery safety.