Your 10,000mAh Power Bank Delivers About 6,300mAh: The Honest Capacity Maths

The complaint always arrives about a fortnight after distribution day. Someone from the client’s team messages to say the power bank you supplied “isn’t 10,000mAh—it only charges my phone one and a half times.” Nothing is faulty. The cell really is 10,000mAh. The phone really did receive roughly 6,300mAh. Both statements are true at the same time, and the gap between them is the single most common source of after-sales friction on gadget gifts in Malaysia.

This is the explanation our production team gives buyers before an order is confirmed, rather than after a complaint: the conversion arithmetic, a delivered-capacity table you can hand to a recipient, the wording we recommend printing on the gift insert, and one cross-check that tells you in thirty seconds whether a quoted capacity is honest. It pairs with our custom power bank models we produce, where capacity, ports and casing are listed side by side.

The number on the casing is a cell number, not a delivery number

Every rechargeable lithium cell has a nominal voltage, and for the lithium-ion and lithium-polymer cells used in consumer power banks that figure is 3.7 volts. When a factory prints “10,000mAh” on a casing, it is describing the charge the cell holds at 3.7V. That is not the voltage your phone accepts. A USB-A port delivers 5V, and a USB-C port negotiates 5V or higher.

So the energy has to be converted, and energy—not milliamp-hours—is the quantity that stays constant. Multiply capacity by voltage and you get watt-hours:

That is the whole story. A 10,000mAh power bank that hands a phone about 6,300mAh is behaving exactly as physics requires. Anker, for one, publishes a real-world figure of 6,000–6,500mAh for a 10,000mAh unit once circuit resistance and cable loss are included. The label is simply measuring a different thing from the one your recipient is measuring.

The practical consequence for a corporate buyer is uncomfortable but useful: a 5,000mAh power bank will not fully charge a modern flagship phone. Phone batteries have grown to 4,500–5,500mAh while the pocket-sized gift power bank has stayed at 5,000mAh, and the conversion loss sits in between. If the brief is “something that gets a guest through a full conference day”, 5,000mAh is already the wrong answer.

Where the missing milliamp-hours actually go

Four losses stack up between the cell and the phone battery, and only the first is fixed by the laws of electricity:

1. Voltage step-up. The boost converter raises 3.7V to 5V and sheds the difference as heat. This is the big one and it is unavoidable in any USB power bank ever made.
2. Cable and connector resistance. A thin, long or cheaply terminated cable drops voltage on the way. The bundled cable in a gift set is often the weakest link in the entire product.
3. The phone’s own charging circuit. The receiving device converts 5V back down to its own cell voltage, losing a second slice.
4. Heat and use during charging. A phone charging with the screen on and mobile data running converts a meaningful share of the incoming energy into brightness and radio power rather than stored charge.

Wireless charging adds a fifth stage: inductive transfer introduces another conversion between the two coils, and they must be aligned for it to work well at all. Wireless models photograph beautifully and feel modern, but they are the wrong choice if the brief is maximum charge delivered per gram carried.

The delivered-capacity table we hand to buyers

Below is the table our team works from when a client asks “which capacity should we order?” The right-hand column assumes a 4,500mAh phone battery, which is a fair 2026 average across mid-range and flagship Android handsets, and it accounts for the phone-side conversion loss as well as the power bank’s. Treat these as bench figures for a fresh unit at room temperature.

Read the fourth row carefully before you fall in love with it. A 20,000mAh unit is the only capacity here that genuinely covers a two-day trip without a wall socket, and it is also the heaviest, the slowest to recharge and the most awkward to brand. Capacity is a trade, not a score. Three briefs, three answers, based on what we see actually work:

• Conference and exhibition giveaways — 10,000mAh. It survives a full day of a hot hall with the screen on, and it is still slim enough to slip into a lanyard pouch.
• Executive and long-service gifts — 10,000mAh in aluminium with laser engraving, or a wireless model if the recipient carries a compatible phone. Perceived quality beats raw capacity here.
• Mass consumer giveaways and roadshows — 5,000mAh only if the messaging is honest about it. Call it a top-up, never a “full charge”, and the gift lands well.

The 30-second cross-check that catches an overstated capacity

Here is the trick worth taking away from this whole article. Watt-hours are voltage-independent, which makes them the only capacity figure that cannot be quietly inflated. Every rechargeable lithium battery intended for shipment carries a watt-hour rating, because airlines and freight rules are written in watt-hours rather than milliamp-hours. So you can audit any quotation with one multiplication:

The same watt-hour figure governs how the goods travel and what your recipients may carry onto a plane. We have set out how lithium batteries actually travel in bulk separately, including the watt-hour thresholds Malaysian carriers apply to passengers — a capacity chosen without reference to those thresholds can become something a recipient is asked to surrender at a boarding gate.

What to print on the insert card—the exact wording

The cheapest complaint-prevention tool in corporate gifting is a small printed card in the box. It carries your client’s branding and it resets expectations before the recipient forms them. This is the structure we recommend, and it is deliberately plain-spoken:

The third line matters more than buyers expect. Lithium batteries are required to move at a low state of charge, so a brand-new power bank very often arrives showing one or two indicator lights. Without a sentence of explanation on the card, a proportion of recipients will conclude the unit is old stock. The freight rule that causes it is explained in full in the shipping article linked above.

How we brief capacity on a Malaysian corporate order

Aquaholic Gifts has been a Singapore-based corporate gifting specialist since 2003 and now serves Malaysia from Kuala Lumpur, and the sequence below is the one our team runs on every gadget order. It exists because capacity decisions taken at the wrong point in the calendar are expensive to reverse.

1. Define the moment of use, not the specification. A full conference day, an overnight outstation trip, a two-day trade show. The moment determines the capacity; the capacity does not determine the moment.
2. Convert the moment into watt-hours. Use the table above. Write the Wh figure into the internal brief so nobody substitutes a smaller cell later.
3. Check the casing can carry the artwork. A slim 10,000mAh card has a flat face that suits full-colour work; a 20,000mAh body is thicker and more curved. Casing and decoration decide each other, which is why we cover what separates two identical-looking power banks as a separate topic.
4. Confirm the paperwork before the purchase order. Statutory bodies buying through ePerolehan will ask for documentation, and the answers must exist before the item is committed — see the certification paperwork a procurement team will ask for.
5. Approve a physical mockup on the actual casing. Screen colours lie; anodised aluminium and soft-touch plastic take ink and laser differently.
6. Lock the calendar. Minimum order quantity is from 300 pcs. Production runs 21–45 days after artwork approval, depending on capacity and branding, plus about 15 days shipping. Express production in 10 working days is available on limited models and quantities.

Questions buyers ask us about capacity

Is a 10,000mAh power bank that delivers 6,300mAh defective or mislabelled?

Neither. The 10,000mAh figure describes the cell at 3.7V, and the delivered figure describes the output at 5V after conversion losses. Both numbers are correct measurements of different things. A unit is only mislabelled if the watt-hour marking on the casing does not reconcile with the milliamp-hour claim.

Which capacity gives the best perceived value for a corporate gift in Malaysia?

10,000mAh, by a clear margin. It delivers roughly one and a half phone charges, stays slim enough to look considered rather than bulky, sits comfortably under airline watt-hour limits, and offers a flat branding face. It is the capacity we specify most often for KL conference and appreciation gifts.

Does fast charging change how much total energy the power bank delivers?

Not materially. Power Delivery and Quick Charge change how quickly energy moves, not how much is stored. A fast-charge model refills a phone in less time and refills itself in less time — a real convenience benefit — but the total charge available is still governed by the cell’s watt-hours.

Why do power banks arrive only partly charged?

Because transport rules require lithium-ion batteries shipped on their own to travel at a low state of charge. It is a safety requirement, not a sign of old stock — say so on the insert card.

What is the minimum order for a branded power bank?

From 300 pcs per design. Below that, decoration setup and cell sourcing stop being viable for a customised run.

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