An ampere-hour (Ah) is a unit of measurement for electrical energy storage that expresses the amount of electrical charge a battery can store. It shows how much current a battery can provide over a given period of time before it becomes discharged.
What does ampere hour mean?
The ampere-hour indicates how much current (in amperes) the battery can deliver for one hour:
Formula: Capacity ( Ah ) = Current he ˝ sè g ( A ) × Time ( h )
Example: A battery with a capacity of 10 Ah can deliver 10 amps of current for 1 hour, or 1 amp for 10 hours.
What is an ammeter used for?
The ampere-hour is most often used to express the capacity of batteries, for example:
- In car batteries: The amp-hour rating shows how much energy the battery can provide to the vehicle when starting or operating.
- In solar energy systems: The capacity of the battery determines how much solar energy can be stored and used later.
- In portable devices: The amp-hour rating determines how long the device will run on a single charge.
Relationship between ampere-hour and power (energy)
The ampere-hour does not directly represent the energy content, but the electrical charge that can be stored. To calculate the energy, the battery voltage (volts, V) must be taken into account:
Energy (Wh) = Capacity (Ah) × Voltage (V)
Example: A 12 V, 100 Ah battery can store a total of 1200 Wh (1.2 kWh) of energy.
What affects the ampere hour?
Discharge rate (C-rate): The capacity of the battery may vary depending on the discharge rate. At higher loads (rapid discharge), the actual capacity may decrease.
Temperature: At low temperatures, the battery's capacity may decrease, while under ideal conditions it provides maximum performance.
Lifespan: Over the course of a battery's cycles, its capacity gradually decreases due to aging.
Summary
Ampere-hours (Ah) are one of the most important measurements of a battery's capacity, showing how much electrical current it can deliver over a given period of time. Knowing the ampere-hour value is essential when selecting and sizing batteries, whether for vehicles, solar systems or portable devices. A battery tailored to your exact needs ensures long-term efficient operation.