A battery charger is a device that replenishes the energy stored in rechargeable batteries. It works by supplying electrical current to the battery, allowing it to regain its charge. Common types of battery chargers include wall chargers, solar chargers, and car chargers, each designed for specific applications and battery types. Battery chargers vary in speed and efficiency, with some offering fast charging capabilities while others provide a slower, more gradual charge. Many modern chargers come with safety features to prevent overcharging, which can damage the battery. Understanding the right charger for your device is essential for maintaining battery health.