Battery labels: volts, amp-hours, and watt-hours

The three numbers answer different questions

Voltage describes the electrical potential of the pack and is tied to the aircraft's power system. Capacity in amp-hours describes charge. Watt-hours describe nominal energy and are calculated by multiplying nominal volts by amp-hours. A 14.8 V, 5,000 mAh label becomes 14.8 × 5.0 = 74 Wh. Convert milliamp-hours to amp-hours by dividing by 1,000 before multiplying.

Watt-hours are the better first comparison when packs have different nominal voltages. A 5,000 mAh pack is not automatically larger in energy than every 4,000 mAh pack; voltage matters. DJI's own battery specification table publishes capacity, nominal voltage, charging limit, chemistry, mass, charge temperature, and watt-hours, which is a useful model for the fields you should collect.

If watt-hours are not printed, calculate them only from values that describe the same pack and state. Do not multiply a charger's output voltage by battery capacity or mix the nominal voltage of one option with the capacity of another. Record the arithmetic beside the source values so someone else can check it.

Nominal voltage is not charger voltage

A pack label may show nominal voltage while the manual separately lists its charging-voltage limit. Those values are intentionally different. Cell count, chemistry, connector, dimensions, battery-management electronics, current capability, and firmware compatibility can all matter. Matching watt-hours or physical fit does not make a substitute safe.

For a camera drone, use only the battery and charging method specified by the manufacturer. For a hobby build, confirm the complete approved combination of pack, charger settings, connector, ESC, motor, propeller, and flight-controller monitoring. Never infer charge settings from a similar-looking pack, and never bypass a smart battery's protection or identification system.

• Write capacity as Ah before calculating: 2,450 mAh is 2.45 Ah.
• Calculate nominal energy: Wh = nominal V × Ah.
• Check the manual for chemistry, cell configuration, charge limit, and temperature range.
• Treat C-ratings and peak-current claims as manufacturer-specific, not directly comparable proof of quality.

Use the label for planning, not prediction

Two packs with the same watt-hours can produce different flight results because mass, voltage under load, current limits, temperature, age, and the aircraft's efficiency differ. Watt-hours estimate stored energy; they do not specify how much of it the aircraft will permit you to use or how it behaves during a hard climb.

Illustrative scenario: two approved battery options are listed for one aircraft. The larger pack has more watt-hours but also adds weight. Compare the manufacturer's aircraft-specific flight-time and weight information, then verify your reserve in normal flying. Do not calculate a proportional endurance gain from watt-hours alone. Keep the label photograph and model number in your field log so a later replacement is checked against the exact manual rather than memory.