What Is an Ah ?

An amp-hour (Ah) is a unit that measures a battery’s capacity, representing how much current it can supply over time. Specifically, 1 Ah means the battery can deliver 1 amp of current for 1 hour before being fully discharged.

Amps (A) vs. Amp-Hours (Ah): What’s the Difference?

• Amps (A) measure current—the flow rate of electricity at a given moment.
• Amp-hours (Ah) measure capacity—how long a battery can sustain a certain current.

Why Do Professionals Use Ah Instead of Watt-Hours (Wh)?

While watt-hours (Wh) might seem more intuitive (since they represent total energy: voltage × current × time), the battery industry prefers Ah for accuracy. Here’s why:

• Battery voltage changes as it discharges, making power (watts) variable.
• Ah remains consistent since it only tracks current over time, making it a more reliable metric for raw battery specifications.

However, once a battery pack includes a voltage regulator (like in power banks or EVs), some manufacturers list capacity in Wh because the output voltage is stabilized.

Key Takeaways

✔ Ah = Capacity (How long a battery lasts)
✔ A = Current (How much electricity flows at once)
✔ Battery industry uses Ah for precision (Voltage changes during discharge)
✔ Consumer devices may use Wh (When voltage is stabilized)

Now you know why your phone battery is rated in mAh (milliamp-hours), while your laptop might use Wh (watt-hours)!