Power Bank Buying Guide: Capacity, Flight Safety Limits & Fast Charging

Never Run Out of Charge on the Move

Whether you are commuting across London, traveling overseas, or camping in the countryside, a reliable portable charger is an indispensable safety net. However, selecting the right capacity requires understanding how battery power actually works.

Understanding Capacity: mAh vs Wh

Battery capacity is typically advertised in milliampere-hours (mAh). Here is what different capacity tiers deliver in practice:

• 5,000mAh: Ultra-slim pocket emergency pack. Provides 1 full charge for standard smartphones.
• 10,000mAh: The sweet spot for daily commutes. Provides 2–2.5 full charges for iPhone / Android phones.
• 20,000mAh: High-capacity travel companion. Charges smartphones 4–5 times or a MacBook Air once.
• 26,800mAh (99Wh): The maximum allowed capacity on commercial flights without special airline approval.

Aviation Flight Compliance (100Wh Rule)

Aviation authorities restrict lithium-ion batteries based on Watt-hours (Wh). The formula to calculate Watt-hours is:

For a standard 26,800mAh battery operating at 3.7V internal cell rating: (26,800 × 3.7) ÷ 1000 = 99.16 Wh. This keeps you safely inside the 100Wh carry-on limit!