Wise deployment of airplane mode – when you're watching a set, sleeping or charging – will go a long way. Meanwhile, lithium-sulphur batteries might be a more practical stepping stone: they’re less expensive to make, weigh less and store almost twice the energy of lithium-ion batteries, and are better for the environment. However, sulphur is a poor electrical conductor, so the technology still needs developing. Considering that today's kids are probably more interested in an iPad than a remote control car, it seems an ideal way of Duracell bringing their brand a bit further into the future. Another cool fact about Duracell's offering is that even the biggest is only 203g, considerably lighter than comparable products which is nice. The two USB ports mean that you can charge two devices at once. It offers pass-through charging and cleverly, the efficient circuitry prioritizes charging your connected device first and then funnels the extra energy to your IonBank itself at the same time, so you get the optimum run time out of the time you have spent plugged in.

Duracell USER MANUAL - Duracell

But which one is best? I tried a range of power banks at festivals, on camping trips and flights, as well as during the course of my everyday routine, and reviewed them with the size, weight, charging speed, ease of use and the warranty in mind. The slim Belkin device has 5,000 mAh of power (a quarter of the imuto) and comes with a 6-inch micro-USB cable. It’s much slimmer and lighter than the imuto and Juice (it weighs just 131g), so it’s more of an everyday power bank.

It's a charming look though the plastic case can't help but feel a little less premium than some of the other devices on this list. Still it feels sturdy and has a nice bright set of lights on the side so you can always see how much power you've got left in it. There are two payoff to all this. The first is that the product is more complicated to use than the Power Station or Belkin – you need to take care to get the right cable in the right slot (an exhaustive instruction manual makes this easy, if somewhat time consuming, to learn).

DRPB3010A - PowerBank USB - Duracell Direct co uk

Another point of difference which makes the Moshi IonSlim 10k stand out as are the battery's lithium-polymer cells, which have no ‘memory effect’ (an effect observed in some rechargeable batteries that causes them to hold less charge over time, because the battery appears to "remember" a smaller capacity). You can charge the IonSlim as frequently as you wish; it should stand the test of time. Why we like it: The Daddy of the power banks we reviewed. Powerful, well designed, not too heavy, and brilliantly priced. The best idea that Duracell have had with their power banks is their "pay for what you need strategy". They've released three power banks ranging in size from 3k to 10k. The former will give you one or two charges while the biggest will give you up to five. It takes around three hours to charge from empty (considerably less time than the Juice Power Station), and once charged, Belkin says its tests show that charge will not diminish by more than 50pc even after a year’s time left dormant – all very impressive, and useful. And that's basically what I did. The power bank came in handy when trying to locate a friend to meet for a swim on Hampstead Heath (my phone was on its last legs – isn't it always?), and during last ditch attempts to keep my nieces and nephews entertained with games on long journeys (there’s only so much I Spy any sane adult can handle).Switching off data usage for apps you don't need will save your battery as well as your data usage. Versatility is also worth considering – for example, can you use the charger for multiple devices? What devices is it compatible with? Does it offer pass-through charging (which means you can charge the bank itself, while using it to charge a connected device)? This year, a team at the University of Texas at Dallas published findings in the journal Nature Nanotechnology to show that they will soon be commercially viable, since molybdenum – a metallic element often used to strengthen and harden steel – can be combined with sulphur to improve stability and compensate for poor conductivity.