RECHARGEABLE BATTERY: Power up on your terms with a recharging system that connects to standard outlets and ports. BUILT-IN USB PORT: With a built-in USB port your battery can be charged both inside or outside your Coast light using a micro USB cord. BATTERY CHARGING LEVEL INDICATOR: Check the status of your batteries charge level with our built-in charge level indicator. (Solid red) when charging, (solid green) when fully charged. OVERCHARGE/DISCHARGE PROTECTION CIRCUITS: Over charging and improperly discharging lithium batteries can cause a safety concern and hazerdous risk to the user and it's surroundings. Coast batteries are built with overcharge/discharge protection, ensuring you and your battery are protected.