All recent iPhones offer an excellent smartphone experience, but if there's one area that's lacking slightly, it's battery.
Apple doesn't explicitly disclose the battery capacity on its phones, but it is often thought to be less than similarly priced Android phones.
While the excellent software optimisations of iOS go some way to bridging the gap, it's still an area that could do with improvement on some models. The 1715mAh battery on the iPhone 6s is simply not up to scratch in 2020, while some may even struggle with the 3110mAh cell on the iPhone 11.
That's where a battery case comes in. In exchange for a little extra bulk, they can significantly boost battery life and ensure your device is well protected from bumps, drops and scratches.
Here are our top picks across all the recent iPhone models. Check out our sister site Tech Advisor for dedicated guides to the iPhone 11/11 Pro/11 Pro Max, iPhone X/XS, iPhone 8/8 Plus, iPhone 7/7 Plus and iPhone 6s/6s Plus/6/6 Plus.
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.
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 the cost. It's a high price no doubt, but it is very good, and will make your iPhone last the best part of 2 days.
Check out the full range of iPhone battery cases on the Apple website. Prices start at £89.95, although you'll have to pay £129.95 for the latest models.
Newdery iPhone 11 Pro battery case
If you're rocking one of Apple's latest phones, Newdery's battery case is a good choice.
The stealthy black design houses a 5000mAh cell, enough to provide a full charge to the phone and then some. Once that capacity has been used up, connecting to a computer will charge the iPhone and then case, so long as the lightning cable is connected.
Despite adding some bulk, this case also retains full support for wireless charging.
Runsy 5000mAh iPhone X Battery Case
With the launch of the iPhone XS, XS Max and XR in September 2018, Apple has discontinued the original X, but that doesn't mean you still can't find battery cases for it.
The Runsy battery case for the iPhone X packs a powerful punch at 5,000mAh. Our colleagues at Tech Advisor featured it in the round up of the best iPhone X battery cases.
On the Runsy case, you can turn the battery on and off depending on when you need it, and can leave the case on even when syncing. It supports both wired and wireless headphones.
The Runsy case is protective too with a rugged outer shell and a raised bezel to keep your iPhone X screen from getting scratched.
You can buy it now for £26.99, although it's not currently available in the US.
Zanya iPhone XS Max Battery case
The Zanya case proves that battery cases can look good and deliver a serious battery boost at the same time.
The soft silicone design makes it a comfortable hold, while its 4000mAh capacity means it can fully charge your phone and have capacity left over. If you're ever in doubt, an LED light indicator on the back of the case will ensure you know when it needs charging.
Mophie Juice Pack Air
This case, which also allows wireless charging, is available for the iPhone 7 or iPhone 7 Plus (which works with the iPhone 8 and iPhone 8 Plus respectively).
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 2,525mAh, which is enough to completely recharge your iPhone.
Moshi Ionsuit battery pack and case
Moshi has made a name for itself in the accessories business, and this clever case helps 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 the battery pack on and off while still having protection, this is the one.
It's available for the iPhone 7 or iPhone 8.