Powerbanks

Capacity: the number on the box is not what reaches your phone. The mAh figure is the battery inside. Anker explains that after voltage conversion and circuit losses, a 10,000mAh pack delivers about 6,000mAh at your phone's 5V. As a rough guide:

• 10,000mAh: a daily top-up.

• 20,000mAh: travel and power cuts.

• 30,000 to 40,000mAh: long trips, and laptops if the pack has the output.

Speed. For iPhone fast charging, pick USB-C PD at 18W or more; a 20W PD pack does it. Samsung's Super Fast Charging uses PPS, so check that the listing says PPS. For a laptop, look for 65W or more, such as the Romoss PEA40S Pro (65W) or the Anker 87W pack with its built-in 65W USB-C cable.

Flying. Power banks go in hand luggage only. Packs up to 100Wh need no approval; 101 to 160Wh need the airline's OK. A 20,000mAh pack is about 74Wh (20Ah × 3.7V). Airlines can be stricter, so check yours.

Spotting a fake.

• Do the label maths: mAh × 3.7 ÷ 1,000 should come close to the Wh printed on the pack. A "20,000mAh" pack labelled 37Wh holds about 10,000mAh.

• Anker packs: check the security code on Anker's verify page, if the box has one.

• Our open-box packs state their condition, including how much they have been used.

Where to start

• 1Hora 22.5W power bank, 10,000 or 20,000mAh, with an LED display

• Romoss WMS10, 10,000mAh magnetic: 20W wired, 15W wireless, built-in cable

• Mophie Essentials 20,000mAh, 20W USB-C PD

Shop by size: 10,000mAh · 20,000mAh · High-capacity. Every listing shows its warranty.

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