
CUKTECH 45W 20,000mAh Power Bank
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From pocket-size magnetic top-ups to full-day battery packs — ranked by the charge you actually get, not the number printed on the case.
Rated capacity is the least useful number on the box. We weigh real-world charges delivered, output wattage, recharge time, weight against capacity, and whether the bank is airline-legal. Magnetic banks are judged separately, because wireless transfer costs you roughly a quarter of the stated capacity before it ever reaches your phone.
Sorted by Tiny Tech Box Score. Prices are Amazon’s at last check and move constantly.

Every pick below links to its full five-aspect review.

















Two reasons: wireless charging loses 20-30% of the energy as heat, and the bank’s cells run at a lower voltage than your phone’s battery. A cabled 5000mAh bank gets close to one full charge; a magnetic one gets you roughly half.
Anything under 100Wh goes in your cabin bag without a declaration — that covers every bank on this page. Power banks must never go in checked luggage.
Magnetic if you want a top-up with no cable and no bulk, and you use a MagSafe case. Cabled if you want the most charge per dollar and per gram. Magnetic banks cost more and deliver less.
Look for 20W or higher USB-C output for full iPhone fast-charge speed. 18W banks work but noticeably slower; anything below that is overnight-only.
Disclosure: As an Amazon Associate, Tiny Tech Box earns from qualifying purchases. Recommendations are based on our own research and scoring, described in full on our How We Score page.