It's no secret that iPhone owners often struggle with battery life issues, and that iPhones are pretty easy to break. That's where battery cases come in, both protecting from bumps, knocks and scratches, and giving the power a boost.
We've tested lots of battery cases for iPhone, including the iPhone 6s, iPhone 7, iPhone 8 and Plus models. If you've already got a case and would prefer a separate battery pack, check out our article on the best power banks for iPhone.
Otherwise read on for our pick of the best battery cases you can buy.
Apple iPhone 7 Smart Battery Case
Following the initial scepticism about the design of the Smart Battery Case, it turns out it's a very well performing, useful accessory.
It looks a bit peculiar - it's a fairly standard silicone case that allows you to easily insert and remove the iPhone, but with an extra portion that bulges out from the case and houses the battery, which should give you up to 25 hours more power.
The one downside to having is that it costs £99. It's a high price no doubt, but it is very good, and will make your iPhone last the best part of 2 days.
Apple doesn't strictly sell a Smart Battery Case for iPhone 8, but this iPhone 7 model fits with no problems. There's no Smart Battery Case for the iPhone 7 Plus or 8 Plus, though.
Apple iPhone 6s Smart Battery Case
The Smart Battery Case is also available for the iPhone 6/6s.
What's interesting is that Apple has added an intelligent battery status that works with the case to show you how much charge you have left on the phone and case, and that information can be found on the iPhone lock screen and in the Notification Centre. It's also charged via Lightning cable and not Micro USB like many others in our roundup.
Mophie Juice Pack Air
This case is available for the iPhone 7 or iPhone 7 Plus (which work with the iPhone 8 and iPhone 8 Plus respectively). US shoppers can find the iPhone 7 Plus version on Amazon for $53.96.
Battery cases are a bit of a mixed bag - they provide extra power and protection for your iPhone, but they’re often rather large and chunky and can spoil the look of the iPhone's slimline design. However, Mophie's Juice Pack Air is slimmer and more elegant than many rival cases, while still providing a really big boost to battery life when you need it.
However, Mophie's Juice Pack Air is slimmer and more elegant than many rival cases, while still providing a really big boost to battery life when you need it.
It looks very much like a conventional protective case, with a tough rubber housing that can withstand bumps and drops. We also like the raised bezel around the edge of the screen, which helps to protect it when you place it face down on a flat surface.
The case does obscure the ports on the bottom edge of the phone, but Mophie includes a headphone adaptor and micro-USB cable so that you can still charge the phone and listen to music without having to remove the case.
And, despite the slimline design, the Juice Pack Air manages to provide a battery capacity of 2525mAH, which is enough to completely recharge your iPhone.
The Juice Pack Air allows wireless charging through the case, too (iPhone 8 and 8 Plus only).
Anker PowerCore 2200mAh Battery Case for iPhone 7
This is a decent, cheaper alternative to Apple's official cases. It fits the iPhone 6, 6s, iPhone 7 and iPhone 8.
The battery is enough to add up to 11 hours of talk time, 7 hours of video or 9 hours of audio. It also doesn't cover the Lightning port so if you have an iPhone you can still plug headphones in.
The build quality isn't as good as Apple, but at about £60 cheaper you may not mind.
Moshi Ionsuit battery pack and case
Moshi is making a name for itself in the accessories business of late, and this clever case will help that.
It is a slide on battery pack but you can use the case on its own when not in use. If you want the quick convenience of a battery case but the option to take it on and off and still have protection, this is the one.
It's for the iPhone 7 or iPhone 8.
Savfy Battery Case
Although around the same weight as the Mophies, because it’s slimmer the Savfy Battery Case feels lighter and more portable. Its 3,200mAh battery capacity is impressive, and will easily give you a full recharge, with some left over for later.
It’s a two-part design, with a solid-looking plastic bumper and hard-shell backplate, which features a handy LED battery-level indicator. You fit the iPhone into the backplate, then snap the bumper over.
It comes with a charging cable and pass-through jack so that angled headphone jacks will fit.