Production · Power
Add every device that will be switched on. Watts × hours = watt-hours, the unit batteries are rated in.
Planning estimates. Device watts are typical; check the label or manual for yours. All devices are pooled onto one battery type, as if run from a shared plate; with separate batteries per device the total energy is the same. Usable capacity allows for cold, age and conversion losses. Power bank: 20,000 mAh × 3.7 V ≈ 74 Wh. Airline limits are general guidance (spares in carry-on only; up to 100 Wh each; 100–160 Wh with airline approval, max 2; over 160 Wh not allowed). Check your airline.