Whereas the Anker power bank offers 3200mAh of power, this Aukey has 5000mAh. However, you also need to consider the efficiency of the power bank, and while Anker claims 90 percent is available to the user, Aukey makes no such claims. With the industry averaging 65- to 70 percent efficiency, you can reasonably expect just short of 3500mAh from the Aukey, but 2880mAh from the Anker. That 620mAh difference is the equivalent of a third of a charge for most iPhones, and less for many Android phones. Also see:  How to improve smartphone battery life. When you consider that the difference in effective capacity is much smaller than you might assume, the 90x30x30mm, 131.5g Aukey starts to look rather chunky beside the 95x23x23mm, 86g Anker. Both are marketed as ‘lipstick-style’ chargers, but while they may be a similar height and feature a cylindrical design, we know of no lipstick quite so wide. But there are other things we like in the Aukey’s design that set it aside from the Anker. Firstly, this Aukey has no physical buttons – merely a Micro-USB input and a USB output. You don’t need to worry about pressing buttons to start or stop charging, you just plug in your phone or tablet to begin charging, and the Aukey supports auto-off once it’s full. Also see:  Best desktop chargers 2015. The Aukey also offers faster charging for your mobile device, providing 7.5W of power against the Anker’s 5W. Both claim to feature intelligent technology that recognises your device type and delivers the optimum amount of power, but in truth all devices will take only the power they require. Still, the Aukey will prove a better choice for charging a tablet with its faster output, and you won’t need to wait around so long to fill up a phone either. Both devices have 5W Micro-USB inputs, which come into play when refilling the power bank. We like the fact the Aukey appears to support passthrough charging, too, allowing us to simultaneously charge both it and our connected  Samsung Galaxy S6. In common with the Anker power bank, neither device has any way of telling you how much power remains inside the bank. However, it’s likely that you won’t get much more than one full charge for your Android phone, or two for your iPhone, so it should be fairly easy to work out when you need to recharge it based on how much you’ve used it. Read next:  How to charge your phone or tablet faster. Follow Marie Brewis on Twitter. Marie is Editor in Chief of Tech Advisor and Macworld. A Journalism graduate from the London College of Printing, she’s worked in tech media for more than 17 years, managing our English language, French and Spanish consumer editorial teams and leading on content strategy through Foundry’s transition from print, to digital, to online - and beyond.