Drone battery watt-hours vs advertised flight time
My drone battery is spec'd at 38 minutes flight time. I've never gotten more than 27, and 22 in wind. The manufacturer number is measured in specific conditions and the airline paperwork wants the actual watt-hours, not the flight time.
Drone battery capacity is quoted in mAh (milliamp-hours) and voltage; the useful number is Wh = mAh × V / 1000. A DJI Mini 3 battery: 2453 mAh at 7.38 V = 18.1 Wh (the intelligent flight battery includes electronics so DJI lists the higher 38 Wh 'plus' battery separately). A Mavic 3 battery: 5000 mAh at 15.4 V = 77 Wh. FAA/IATA rules cap lithium batteries in carry-on at 100 Wh without special permission — most consumer drones sneak under this, professional ones don't.
Why advertised flight time lies
The advertised number is hover in windless calm conditions with a fresh battery at ideal temperature (usually 20-25°C). Real flight includes movement, wind resistance, camera gimbal loads, and battery voltage sagging under load. 60-75% of advertised flight time is normal in mild conditions; 50% is normal in wind or cold.
The reserve
Modern drones auto-land at 15-25% battery to reserve energy for return-to-home. That reserve isn't in your flight time budget. A 38-minute advertised battery gives you maybe 30 minutes of actual flying and 8 minutes of reserved-for-landing energy.
Temperature crushes Wh
LiPo batteries lose 20-30% of usable capacity at 0°C, 40-50% at -10°C. Flight time in cold weather is not the same battery you had in summer — the Wh label is the same but the delivered energy is less because internal resistance rises and voltage sags earlier.
Recap
Wh is the honest capacity number. Advertised flight time is best-case. Real time is 60-75% of advertised, less in wind and cold.
Try the converters mentioned in this article
FAQ
How many batteries for airline travel?+
FAA allows two spares up to 100 Wh each in carry-on (not checked). Above 100 Wh you need airline approval; above 160 Wh generally not allowed.
Storage voltage?+
LiPo lasts longest stored at 3.7-3.8 V per cell (about 50-60% charge). Full-charge storage for months damages the pack.
This article was written by The Turbo Unit Converter engineering desk (Applied metrology & engineering units) and last reviewed on 2026-07-23 against NIST SP 811 and the BIPM SI Brochure. Read our full editorial policy.