To help you out, note that it typically takes 2,500 to 3,500mAh to charge a modern smartphone (though many factors can affect power consumption). Charging a GPS unit or digital camera is likely to consume a similar amount of power, while charging a head torch, smartwatch or GoPro will consume much less. High-powered devices like tablets and laptops are the biggest drain on battery capacity. Another compact and relatively lightweight power bank with an integrated solar panel that can fully recharge its 6,000mAh internal battery in 28 hours of sunlight. However, with the Supercharger solar panel attached, charge time is reduced to around 8 hours, or 6 hours if all the solar panels are in direct sunlight. The Freeloader Sixer has a 2.1A USB output as well as integrated micro-USB and lightning cables, enabling up to three devices to be charged simultaneously. Lithium batteries gradually lose their charge capacity with every recharge. It’s not like an on-off switch where the battery will work one minute and then stop the next. The total amount of power that the battery can store just gradually becomes less until it really starts to drop off.

One advantage of this shift to USB-C is that power banks now support USB PD for faster charging. This means your power bank will often recharge faster when connected to a suitable fast charger, at anywhere from 20W to 60W. At those speeds, even a high-capacity charger can recharge fully in three to four hours.

Guide To Power Banks

If you are trying to get as much out of the bank as possible, don’t actively use the phone and leave it overnight on the 0.5A output. Switching it off while charging would be optimal. This is the sort of scenario you’d encounter while camping away from mains power. Where every watt counts.

To see how this makes a difference we need yet another unit, the watt hour (Wh). This is the unit your electric bill is measured in and indicates the actual energy used. Fully charge all your devices before you head out – that way you can save your power bank’s juice for when you really need it Ports: Different devices have different charging ports, and your power bank should be compatible with them. Look for power banks with the right ports, such as Lightning or USB-C, to ensure seamless charging for all your devices. Having multiple ports is a bonus, allowing you to charge multiple gadgets simultaneously.

GP Batteries Charge AnyWay

Charge it Fully: Plug in your power bank and let it charge fully before using it. This ensures that it's ready to provide a reliable power source when you need it.

With USB-C and twin 2.4A USB outputs, the GP Batteries M-series power bank supports the latest devices and offers speedy charging. You can charge up to three devices simultaneously. The 15,000mAh capacity gives a real-world performance of about four to five smartphone charges (though the manufacturer quotes six). It’s very simple and easy to use – a single button with four LED indicator lights and device auto-detection means you can just plug in and go. It is supplied with a 2-in-1 micro-USB and USB-C cable. Using an mAh to Wh calculator, we see that at 3.7V our 10 000 mAh power bank has 37 Wh of energy. However, our 2500 mAh phone battery charged at 5V needs 12.5 Wh. That only give us about three full recharges rather than four at best! This Ravpower Xtreme power bank boasts triple 2.4A USB ports so you can charge three devices simultaneously at high speed. An impressive array of built-in technology protects against overheating, overcharging, short circuits and power surges. It also automatically adjusts charge output and voltage for optimum charging speeds. It’s incredibly simple to use, with a single button that displays a four-LED power indicator to let you know how much juice you have left. Not that you’re likely to run out, given the whopping 26,800mAh battery capacity. That gives you nine full charges for the iPhone X, which is impressive. It is supplied with a micro-USB cable and a travel pouch. With a power bank, though, you can always get a recharge – even when you’re far from home. In fact, with bigger power banks, you can get away for a weekend or go camping and still keep your phone juiced up. And it’s not only smartphones that can benefit. Tablets, digital cameras and Bluetooth speakers can often do with a top-up, and a decent power bank is a must-have accessory if you love playing on a Nintendo Switch. Capacity: The capacity of a power bank is measured in milliampere-hours (mAh), but this can be a little misleading because the amount of power you get out depends on the cable you use, the device you are charging, and the charging method (Qi wireless charging is less efficient). You will never get the maximum capacity. We try to provide an estimate of what you’ll get in terms of charges for devices.If you care more about convenience than speed, wireless charging is very much the way to go – and a growing number of power banks support it. Just place your smartphone on the integrated wireless pad, and you can recharge without connecting any cables. There will be a hit on charging speeds, so you’ll be limited to 7.5W or 10W, but that’s not a big issue if you don’t need to recharge in a flash. As a bonus, we’re now seeing Magsafe-friendly chargers that will clamp onto an iPhone or a ring inside an iPhone case, meaning you can recharge your iPhone even while you’re using it. How we test power banks