The Keeppower S1 is a versatile single bay battery charger designed to power up a wide range of Li-ion rechargeable batteries. Compatible with multiple battery sizes including 32650, 26800, 26700, 26650, 21700, and 18650, this charger offers remarkable flexibility for various devices. The S1 features a user-friendly design with LED indicator lights that clearly display charging status - red while charging and green when fully charged. Built-in high-precision MCU and real-time temperature control protection system, with over-current protection, over-charge, over-voltage, and short-circuit protection. The charger will automatically stop charging after fully charged batteries. With an input of DC 5.0V-2.0A and output of 4.20V-2.0A, this charger efficiently powers your batteries through any USB power source, whether it's a power adapter, laptop, or power bank. The sleek black housing and compact single-slot design make it perfect for both home use and travel. Simple to operate and reliable in performance, the S1 charger is an essential tool for anyone using rechargeable Li-ion batteries in their devices.