The battery life on the Galaxy S9 isn't stellar, while the S9+ isn't much better. If you find your phone isn't lasting you all day or your simply need more juice on the go and don't want to lug around an extra portable battery, then check out these battery cases and always keep that extra power ready whenever you need it.

ZeroLemon Slim Power 4700mAh

Featuring a 47,00mAh battery, this case is capable of providing a full charge to your Galaxy S9 or S9+ and features all the protection you'd expect from a case, too. On the back is an LED indicator that uses different colors to let you know how much bonus battery life you have remaining. This case also supports passthrough data transfer and charging via USB-C and will let you get way more out of your phone for reasonable price.

ZeroLemon ZeroShock 8000mAh

Battery cases are sometimes considered to be too bulky — and it's totally understandable if you think this case is way too bulky for your Galaxy S9 or S9+. The ZeroLemon ZeroShock case is a behemoth. It's nearly an inch thick and designed to combine a massive 8,000mAh battery with a rugged phone case design that's perfect for the outdoorsy types who want to have your phone available for photos or for emergency situations.

Alpatronix BX440 4000mAh

Alpatronix's case is well reviewed on Amazon and offers a good combination of bonus battery life with a design that protects your phone while keeping all the functionality intact. There's a front lip around the display to defend against screen damage when you place your phone screen down, and there's a USB-C port at the bottom that can be used for both charging and data transfer purposes. This case also supports wireless charging using virtually any Qi wireless charging pad.

PowerBear USB-C charging case 4500mAh

PowerBear's battery case for the Galaxy S9 and S9+ can give your phone at least one full charge (depending on usage), and it's designed with protection in mind. There's no denying that it's quite bulky, but that bulk means protection for both your phone and the case itself in case you drop it. There's a handy on/off switch so that you're not wasting battery when you don't need a top-up.

Elebase battery case 4700mAh, 5200mAh (S9+)

This case from Elebase is available for both the Galaxy S9 and S9+, offering a clean and simple design with a single LED indicator to let you know how much juice it has left. It's one of the more sleek designs available on our list and just might hit the sweet spot for you in terms of battery capacity.

Mophie Juice Pack 2,070mAh

Mophie's Juice Pack series uses high-quality batteries in a relatively slim form factor to keep your S9 juiced up on the go without the bulk. These cases won't charge your phone fully, but they will provide a top-up when you need it. They have an on/off button, and they're Qi-compatible, so you can wirelessly charge them up when you have the opportunity.

Get more daily use out of your Galaxy S9 or S9+

If you find that you Galaxy S9 or S9 Plus just isn't lasting as long as you need it to, a battery case is a great solution so that you don't have to stop and wait for it to charge. There's a good number of options available, and you'll want to consider the different battery capacities available and how each will affect the physical size and shape of your phone.

The ZeroLemon Slim Power (opens in new tab) is the best battery case for most people, since it's fairly affordable and can reliably charge your phone at least once fully. If bulkiness is no issue and you want the most extra battery life that money can buy, you should absolutely get the ZeroLemon ZeroShock (opens in new tab) case that offers a whopping 8,000mAh of juice.

However, if you've gone through this list and decided that you don't want a battery case after all, there are plenty of other caes for both the Galaxy S9 and the S9+ that are available.