The capacity of an alkaline battery varies significantly depending on its size and the discharge conditions, but a typical AA alkaline battery has a capacity rating of over 2,500 mAh.
While "capacity" is often used to describe a battery's ability to deliver power over time, it's crucial to understand what that number represents and how it translates into real-world usage.
Understanding Battery Capacity
Battery capacity is generally measured in milliampere-hours (mAh) or ampere-hours (Ah). This rating indicates the amount of electrical charge a battery can store and deliver. For example, a 2500 mAh battery can theoretically deliver 2500 milliamps of current for one hour, or 1250 milliamps for two hours, and so on.
However, the actual usable capacity is influenced by several factors:
- Discharge Rate: Higher discharge rates (drawing more current) typically reduce the battery's effective capacity. The faster you drain the battery, the less total energy you'll get out of it.
- Temperature: Extreme temperatures can negatively impact battery performance and capacity.
- Cut-off Voltage: Devices typically require a minimum voltage to operate. As a battery discharges, its voltage drops. When it reaches the "cut-off voltage" of the device, the device will stop working, even if the battery still has some charge left.
- Battery Age & Condition: Over time, batteries degrade, and their capacity diminishes.
Typical Alkaline Battery Capacities (Approximate)
The following table provides approximate capacity ranges for common alkaline battery sizes:
| Battery Size | Typical Capacity (mAh) |
|---|---|
| AAA | 800 - 1200 |
| AA | 2500 - 3000 |
| C | 3800 - 8000 |
| D | 8000 - 18000 |
| 9V | 400 - 600 |
Important Note: These are typical values. Actual capacity can vary depending on the brand, quality, and specific application. Always refer to the manufacturer's specifications for the most accurate information.
Alkaline vs. Rechargeable Batteries
It's important to note that comparing alkaline and rechargeable batteries (like NiMH) solely based on mAh ratings can be misleading. For example, an AA alkaline battery may have a higher mAh rating than an AA NiMH battery (e.g., 2500 mAh vs. 2000 mAh). However, NiMH batteries often maintain a more stable voltage during discharge and can deliver higher currents, leading to longer runtimes in some devices, especially those requiring higher power. As the reference indicates, a device like a digital camera may run much longer on an NiMH battery despite the lower mAh number.
