Ampere-Stunden (Ah) is a unit of electric charge that measures the amount of electricity a battery can store and deliver over time. One Ampere-Stunde represents the flow of one Ampere of current for one hour. This measurement helps determine how long a battery can power a device before needing a recharge. For example, a battery rated at 10 Ah can theoretically provide 10 Amperes of current for one hour, or 5 Amperes for two hours. Understanding Ampere-Stunden is essential for selecting the right battery for various applications, such as in electric vehicles or portable electronics.