Built-in rechargeable lithium battery with automatic charging feature: The bulb is equipped with a built-in rechargeable lithium battery, eliminating the need for external batteries. It features an automatic charging feature that charges the battery whenever the bulb is connected to a power source. 8-10 hours for a full battery charge: It takes approximately 8-10 hours for the bulb's built-in rechargeable lithium battery to fully charge. This allows you to quickly replenish the battery for the next use. Backup of up to 4 hours: The bulb offers a reliable backup of up to 4 hours, ensuring continuous illumination during power outages or emergency situations. Versatile functionality: In addition to its emergency lighting capabilities, this bulb can be used as a regular light source in everyday situations. Whether you need it for emergency preparedness or general lighting needs, it offers versatility and convenience. Reliable and efficient: Philips, a trusted brand in lighting, ensures that this emergency LED bulb delivers high-quality performance and durability. It is designed to provide efficient and long-lasting illumination when you need it most.