Battery charging is the process of replenishing the energy stored in a battery, typically using an external power source. This is done by applying a voltage that forces electric current into the battery, allowing it to store energy for later use. Common types of batteries include lithium-ion, nickel-metal hydride, and lead-acid, each requiring specific charging methods to ensure safety and efficiency. Charging can occur through various methods, such as using a wall charger, solar panel, or wireless charging pad. The charging time depends on the battery's capacity and the power output of the charger. Proper charging practices help extend battery life and maintain performance.