For those days when battery life becomes an issue, you can't always rely on a wall or car charger to give you the boost you need. Having a reliable iPhone 6s battery case on hand can make the difference between a dead device and one that will keep on keepin' on — no matter what. While some manufacturers are still crafting their battery cases, there are already a handful of options available for your new iPhone 6s that are worth scooping up early.

And, if you're unsure about investing in a battery case, you can check out some easy fixes for subar battery life on the iPhone 6s that may be of some help in the meantime.

1. Supcase Beetle Power Battery Case for iPhone 6s

Our first and favorite of the bunch is the MFI-certified Supcase Unicorn Beetle Power Case for iPhone 6s, packed with enough battery life to suit the most demanding power users. This iPhone 6s battery case manages to provide enough protection against impacts while enhancing grip to prevent them in the first place. Inside is a 3,200mAh battery that keeps things going, covered by a dual-layer casing that features an interchangeable bumper for swapping colors on the fly. It recharges by a microUSB port on the bottom and comes bundled with a handy holster for clipping to a belt or pocket. You can't argue with the easy access to ports and buttons of the iPhone 6s, either.

The Unicorn Beetle Power Case comes at a reasonable $49.99, which is substantially cheaper than some of the big-name competition.

Buy for $49.99 on Amazon

2. PhoneSuit Elite Battery Case for iPhone 6s

Surprisingly thin for an iPhone 6s battery case is the PhoneSuit 3,000mAh Elite. This cover has been crafted to be incredibly sleek with a reinforced construction, strong polycarbonate, and metallic rubber composite materials. On the back is an LED battery indicator that lights up to show how much of the 3,000mAh inside remains. You'll get at least a couple extra charges from this iPhone 6s battery case and enjoy its low-profile design when you see how comfortable it is to use despite packing a battery beneath.

The PhoneSuite Elite for iPhone 6s comes in black, blue, or red for slightly steeper $97.

Buy for $97 on Amazon

3. Trianium Battery Case for iPhone 6s

Trianium has built-up quite the reputation on Amazon with its MFI-certified 3,100mAh iPhone 6/6s battery case, and for good reason — it works and it's affordable. Its durable build doesn't have many frills, but rather sports a more simplistic design that does its job of keeping your iPhone 6s going for the long haul. There's a handy LED battery indicator on the back that lights up by tapping the power button beside it, and the special sync-through technology allows you to connect to a computer without popping the battery case off your iPhone 6s. There's even a microUSB charging cable and 3.5mm headphone extension adapter included for good measure.

The Trianium 3,100mAh Battery Case for iPhone 6s comes in a handful of colors to choose from starting at $35.99.

Buy for $35.99 on Amazon

4. Spigen Volt Pack Battery Case for iPhone 6s

Next up is Spigen's Volt Pack Battery Case for iPhone 6s that uses a 3,100mAh battery inside to provide an extra 150% of battery life. The strong polycarbonate shell is great for mitigating damage if and when your iPhone 6s takes a tumble while wearing the battery case. The frame is actually detachable if you decide you want to change colors and the 4 LED lights on the back give a clear approximation of how much battery life is left at any time. Measuring only 15mm in thickness, it's not overly bulky and still leaves access to the ports and buttons of the iPhone 6s.

You can snag the Spigen Volt Pack for iPhone 6s for $35.99, which includes a microUSB charging cable and 3.5mm headphone extension adapter.

Buy for $35.99 on Amazon

5. Anker Ultra Slim Battery Case for iPhone 6s

Packing a 2850mAh battery inside its amazingly slim polycarbonate shell is Anker's Ultra Slim Battery Case for the iPhone 6s. It's MFi certified and able to used for syncing up to your PC or laptop through the case without removing it. The matte exterior enhances grip, helping to prevent unwanted drops, and charging LED's light up on the back to show how much battery life remains after use. Included with the case is a microUSB charging cable, 3.5mm headphone extension cable and welcome guide.

The Anker Ultra Slim Battery Case for iPhone 6s is currently available on Amazon for $39.99 that includes an 18-month warranty.

Buy for $39.99 on Amazon