Power Banks: The Capacity Number Means Less Than You Think

Real-world capacity is well below the printed number, and that is physics rather than dishonesty. Voltage conversion and heat lose a meaningful share of the stored energy, so a 10,000mAh bank delivers roughly two full phone charges rather than the two and a half the arithmetic suggests. Two charges is genuinely the right amount for a day out — enough to be useful, small enough to carry.

The built-in cable is the feature that decides whether it gets used. A power bank in a drawer with no cable beside it never leaves the house. One with the cable attached is a single object you drop in a bag, and that difference is the whole reason this format exists.

The wattage figure matters most for how fast the bank refills itself. A high-wattage input means it recharges in about an hour rather than overnight, which is what makes it usable on the same day rather than something you have to plan around.

• A brother who is out all day and always hunting for a socket
• Anyone who travels, especially long flights with unreliable seat power
• A student moving between campus, library and home
• Someone whose phone is a few years old and no longer lasts a day

• Small enough to actually be carried
• Integrated cable removes the usual excuse
• Useful on precisely the days that go wrong

The things worth checking before you order — this is where gifts like this most often go wrong.

• Check which connector the built-in cable uses against his phone. A bank with an integrated cable is superb for the matching phone and awkward for any other, so confirm whether he is on USB-C or Lightning before ordering.
• Power banks must travel in hand luggage, never in checked baggage — airlines are consistent on this and increasingly strict about it. A capacity at this level is well within normal cabin limits, but the bag it goes in matters.
• Fast charging generates heat, and a small metal body gets warm. That is expected behaviour rather than a fault, though it is worth knowing before it alarms someone.
• Lithium batteries degrade with cycles. Two or three years of regular use before capacity noticeably drops is normal; this is a consumable, not a permanent object.