How many times will a 26,800 mAh power bank charge a phone?
About 4.5 full charges of a typical phone battery (15 Wh), from 3.9 to 5.1 depending on the bank.
A charged phone is how you report the cut, check the outage map and reach people. A 26,800 mAh bank holds about 99 Wh at its 3.7 V cells, of which about 75% typically reaches the USB port, less what the device loses charging its own battery.
The numbers
| Device | Worst case | Typical | Best case |
|---|---|---|---|
| Small phone (12 Wh battery) | 4.8 | 5.6 | 6.3 |
| Typical phone (15 Wh battery) | 3.9 | 4.5 | 5.1 |
| Large phone (19 Wh battery) | 3.1 | 3.5 | 4 |
Phone batteries hold roughly 12 to 19 Wh. Charging a phone while you use it, or with the screen on, gives fewer full charges.
Other sizes
| Power bank | Energy | Typical |
|---|---|---|
| 10,000 mAh | 37 Wh | 1.7 full charges |
| 20,000 mAh | 74 Wh | 3.3 full charges |
| 26,800 mAh | 99 Wh | 4.5 full charges |
| 40,000 mAh | 148 Wh | 6.7 full charges |
Where to buy
A 26,800 mAh power bank
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When a power bank is not enough
A power station runs the same job from a mains socket, for far longer, and runs the things a power bank cannot: the fridge, the boiler's electrics, a mains electric blanket. For example, the Anker SOLIX C300 runs a phone charging for about 16 h 32 min.
If this is for a power cut
For phones and tablets alone, a power bank is the cheaper answer. A power station earns its place when you also need the router or the fridge.
Power bank, 20,000 mAh. Keeps a phone going for days if you use it sparingly.
Look for: Capacity in watt-hours as well as mAh (about 74 Wh for 20,000 mAh), USB-C in and out, and keep it charged.
Plug-in power failure lights. They live in a socket as a night light, charge themselves, and switch on the moment the mains goes off, so you are never hunting for a torch in the dark.
Look for: A built-in battery you can pull out and carry as a torch, and a UK three-pin plug if you are in the UK.
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More: the power cut essentials list (US edition).
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