Portable power packs We review five of the best battery chargers for when you’re out
Carry a rechargeable battery unit and your phone or tablet can last several times longer. Our tips and picks will help you choose wisely
If your phone often runs out of power before you get home, or you’re planning a trip with your tablet away from a plug socket, a portable external battery is the answer. Their capacity is measured in milliamp hours (mah), the same measurement unit quoted for phone and tablet batteries. However, you can’t just divide one by the other to find out how much of your battery it will recharge. The charging process is only 60-70 per cent efficient at best, so Anker reckons its 10,000mah Powercore Speed, for example, will charge an iphone 7 (1960mah) “more than three times”. The Samsung Galaxy S8 Plus has a 3500mah battery, so you’d get fewer top-ups.
All USB devices are designed to charge at 5 volts, needing anything from about 1 amp of current for basic phones to 2.1A for tablets. Phones will charge faster from a two-amp source. Anything above 2.1A was prohibited by the original regulations for USB charging, but it is possible if both the device and power pack support the same fast-charge system. For example, Qualcomm’s Quick Charge 3 technology can support higher wattage, but your power pack will also have to support fast charging on your particular device. Only the highest-capacity packs can even attempt to charge a small laptop. Most are best for phones and adequate for tablets.
Oddly, most power packs don’t come with any way of getting power into them – you’ll need a standard mains charger with the appropriate cable ( microusb or USB Type-c). Some power packs can be charged while charging other devices (‘pass-through’), but others can’t.
Here, we test five of the best power packs around. We also tried the Amazonbasics Portable External Battery Charger (5600mah), but since then the entire range has been discontinued. It was a decent buy at just £11, so if it reappears it’s worth considering.
Recharge your phone or tablet while you’re away from a plug socket