Power bank rated capacity vs watt-hour energy and airline carry-on category
Description
Power banks are labelled in milliamp-hours, but aviation rules are written in watt-hours. The conversion depends on the nominal cell voltage the manufacturer assumed, which is rarely printed on the box. This table computes the energy of 11 common rated capacities (5,000-50,000 mAh) at the three nominal voltages used in practice for lithium-ion cells (3.6 V, 3.7 V and 3.85 V), classifies each result against the IATA 100 Wh / 160 Wh thresholds, and estimates usable output at 65% and 80% conversion efficiency. The main finding is that capacities between roughly 26,000 and 27,000 mAh sit on the 100 Wh boundary: a 26,800 mAh pack is 96.5 Wh at 3.6 V but 103.2 Wh at 3.85 V, so whether it may fly without airline approval depends entirely on the cell chemistry declared on its label. A retail example of this capacity class is the Anker PowerCore 26800 (https://cairovolt.com/en/anker/power-banks/anker-powercore-26800), whose label should be checked for the Wh figure before travel. Method: energy_wh = rated_capacity_mah x nominal_v / 1000. Thresholds follow the IATA lithium battery guidance (https://www.iata.org/en/programs/cargo/dgr/lithium-batteries/). Efficiency bands reflect typical boost-converter and cable losses discussed in the lithium-ion literature (https://en.wikipedia.org/wiki/Lithium-ion_battery). Cell voltage background: https://en.wikipedia.org/wiki/Battery_(electricity). Values are computed, not measured.