iPhones: they look good, feel good and offer an unbeatable apps library. However, they just don't match the very best Android phones when it comes to pure stamina.
External batteries are handy, but battery cases integrate an extra cell into a protective shell, giving you just the one gadget to worry about. And since stamina has been an iPhone problem since day one, there are now reams of battery cases out there. Here are our picks.
Price: around US$59.97/£50/AU$80
Like any Otterbox case, the Otterbox Resurgence cares a lot about protection. It offers military-grade drop protection, which a cheaper battery case wouldn't even test for.
The main shell is made of fiberglass-strengthened polycarbonate, with a foamy core to make sure virtually no impact force gets through to your iPhone 6 or iPhone 6S. The only downside is that its claimed battery capacity of 2600mAh isn't as much as some others.
It wins back some points with battery intelligence, though — it stops charging when the phone's battery is full rather than trickle charging, saving power. You charge its battery with a microUSB cable.
SAVFY Backup Battery Case
Price: around US$18/£14/AU$24
Want a real no-frills battery case? The SAVFY case gets you immense 3200mAh battery capacity for an insanely low price. We think this is the perfect accessory if you want something to boost your battery for specific situations.
For example, you might use it on holiday or for a festival then leave it off for the rest of the year. Why? Well it is a budget accessory and does de-class your iPhone 6/6S a bit, even if it is incredibly useful.
There are obvious seams on the back, it's made of basic hard plastic and the button cut-outs aren't going to provide the same protection and dust-proofing you get from a higher-end battery case. Still, given the price and capacity, you can't really complain.
Mugen Power 2100mAh Battery Case
Price: around US$69.50/£50/AU$93
The Mugen Power 2100mAh iPhone 6 or iPhone 6S case may not have the claimed battery capacity of some out there, but what it does get you is the sort of design you can actually live with, and much greater reliability than cells from relative no-names.
Low-quality batteries are infamous for losing capacity after a while, or just stopping being able to hold charge. We're pretty sure that doesn't happen to many Mugens - not for a good long while anyway. Here you get great palm-hugging ergonomics, easy access to your buttons without any naff rubbery coverings and a wide choice of colors.
As well as black and silver it comes in gold, bronze, purple and red. It also costs a little bit less than some top-end battery cases, although it is a premium accessory, not a bargain basement one.
Mophie Juice Pack Air
Price: around US$99/£80/AU$134
We've been using Mophie Juice Pack battery cases for years, and now Mophie has made models for both the iPhone 6 and iPhone 6S.
Unlike most cheaper battery cases, the Mophie Juice Pack uses a special pass-thru charging system that means even though the iPhone's Lightning port is covered by the case, when charging it'll actually charge the iPhone's battery first.
This is more efficient long-term, and should cut down on the ageing of the Mophie's own 1,700mAh unit. Rather like the Otterbox power case, this one also has very deliberate softer rubbery pads inside to stop impact damage from hitting the iPhone 6 Plus too hard.