The 400mAh lithium battery provides a strong balance of high energy density and compact design, offering reliable and long-lasting power for a wide range of small electronic devices. It is commonly used in applications such as smartwatches, fitness trackers, wireless earphones, medical monitoring devices, remote controls, and wireless sensors. With its stable discharge rate and efficient energy output, the 400mAh battery is particularly well-suited for Internet of Things (IoT) devices that require extended operation without frequent recharging. Additionally, it is widely utilized in smart home devices, wearable technology, and other portable electronics, ensuring consistent and dependable power for modern, connected applications. Its versatility and efficiency make it an indispensable component in today’s portable tech landscape.