While Apple has made some advances in iPhone battery life, most heavy smartphone users of their smartphone will run into that Low Battery warning at some stage of the day. The iPhone X and XS generations are still not able to last a full day and as they are now a few years old, the batteries will be getting weaker with every charge. 

According to Apple, the 2,716mAh cell on the iPhone X will get you 21 hours of talk time, 12 hours browsing the Internet, 13 hours watching video, or 60 hours listening to audio – although not all at the same time, of course!

Macworld has a list of all iPhone battery capacities.

The iPhone XS battery capacity is slightly smaller than the X, at 2658mAh. While the XS’s A12 Bionic SoC chip is more efficient, the smaller cell means battery life is not significantly improved. The XS Max does at least bump this up to 3174mAh, but that still isn't enough for most people!

There aren't a huge amount of Apple-certified cases out there, but you can trust the brands in this round-up to produce a quality product. Other than that you can, of course, buy a no-power protective case - see Macworld's round-up of the best iPhone X cases. And don't forget Macworld's great tips on improving iPhone battery life.

Although some claim much higher capacities we found most of these maxed out at a full recharge, so the 3,200mAh case did nearly as well as the 5,000mAh cases tested here. Even the Apple battery case (with its apparently meagre 1,369mAh capacity) got us a 90 per cent recharge.

Remember most of these are not Apple certified. Though we tested the products reviewed here and they mostly worked fine, Apple recommends using only accessories that it has certified (MFI) and that come with the "Made for iPod/iPhone/iPad" logo.

Mophie Juice Pack Air for iPhone X

Mophie Juice Pack Air for iPhone X

Compatible with: iPhone X

Mophie leads the way when it comes to charging accessories. The Juice Pack Air cushion your battery life so you can use your iPhone X for a total of 30 hours. It has a 1720mAh battery that works with wireless charging too.

It comes with a micro USB cable that you can attach to a computer to charge both your phone and case. The Priority+ features uses pass-through charge to charge your iPhone first, and then the case. 

Aside from a lithe total weight of around 80g, it also has a lithe price of £29.95/US$29.95 right now, which is £70/$70 less than what it typically costs.

Head to Mophie or Amazon now to pick it up now.

The case comes with a 2-year warranty.

Mophie Juice Pack Access for iPhone X/Xs

Mophie Juice Pack Access for iPhone X/Xs

Compatible with: iPhone X, iPhone XS

While we're looking at Mophie, it's also worth pointing out the bigger sibling to the Juice Pack Air, the Juice Pack Access. It offers a higher 2000mAh of power which also makes it slightly more expensive at £49.95/US$49.95.

The Access maintains, well, access to the Lightning port so you can plug in your wired AirPods if you want to without disrupting the charging. 

Pick it up from Mophie or Amazon.

Runsy 5000mAh iPhone X Battery Case

Runsy 5000mAh iPhone X Battery Case

Compatible with: iPhone X, iPhone XS.

The Runsy battery case packs 5,000mAh of power and comes with a power switch that lets you turn the battery on and off as desired.

From a protection standpoint, it has a raised bezel to keep that iPhone X screen scuff and scratch-free. Plus a matte finish adds grip, which is a useful safeguard for unexpected drops.

There's a pull-out stand on the back so you can set your iPhone up in a landscape position on a table or desk.

At 154g, it's heavy and a little bulky, too. 

You start a recharge by pushing the button underneath the large LED battery indicators. In testing, we got a lot of portable power for our money - with over 140% recharge. That's the highest recharge we got in all our iPhone X and XS battery case tests.

The Runsy battery case also supports Apple Lightning wired headphone listening, and can take a Lightning-to-headphone adapter.

It's not currently available in the US. In the UK, you can pick it up from Amazon for £26.99.

Newdery Wireless Battery Case for iPhone X/XS

Newdery Wireless Battery Case for iPhone X/XS

One not to buy

The Newdery Battery Case for iPhone X/XS looks like a real bargain.

It’s a one-piece protective case that offers not just a 6,000mAh (22.2Wh) battery but Qi wireless charging too. This means you can charge both phone and case using a wireless charger – ideal if you hate cables. Only the expensive Apple Smart Battery Case included wireless charging, so this is a much cheaper option.

But here comes the bad news: In real-life testing, the Newdery failed to work, and the power-on button feels flimsy and breakable.

The case weighs 159g, which is a fair bit heavier than the Apple battery case, and is 2.3cm at its thickest depth.

If you're looking for battery cases for other iPhone models, read our roundups of the best battery cases for iPhone 6/6s and 6/6s Plus, the best battery cases for iPhone and 7 Plus, and best battery cases for the iPhone 8). And now you can also find the best battery case for the iPhone 11.