How can you determine the length of time that equipment can be powered from a battery?

Battery capacity is standardized in Ampere-hours (Ah) or milliAmpere-hours (mAh). This rating tells you exactly how much electrical current a battery can supply over a specific period. For example, a 10 Ah battery can theoretically provide 1 Ampere for 10 hours, or 2 Amperes for 5 hours. To determine the total runtime for a piece of equipment, you simply divide the total capacity (the Ampere-hour rating) by the average current the device draws (in Amperes). If your radio draws an average of 2 Amps and you have a 12 Ah battery, it will last approximately 6 hours (12 divided by 2). The distractors use incorrect formulas or irrelevant units. Watt-hours are used to measure total energy, but the standard and simplest calculation for radio runtimes utilizes the Ampere-hour rating divided by current draw. Formulas involving multiplication or squares are mathematically incorrect for calculating time.