13 battery cases and power packs for your iPhone 6 or 6S

Not only does the Apple smart battery case have an off-putting bulbous design, but at $99, the case is expensive for its paltry 1,877mAh battery capacity ("mAh" means "milliampere hours" and is a measurement of the battery's capacity. The higher the number, the longer the battery life.)

As such, there are plenty of other options to juice up your handset that you may want to consider. Click through to see some of our favorites.

The Juice Pack Wireless battery case charges the phone wirelessly through the case, and it includes a powerful magnet for use with various mounts and stands. Mounts are expected to cost around $40 while the case should cost about $100 during launch.

Anker's 2,850mAh battery case increases your phone's life by 120 percent. Its capacity is slight lower than some of the competition, but it's 2.9-ounce weight makes up for it. And, at $40 (or £30 in the UK and AU$53 in Australia at current conversion rates), that's a pretty good deal.

The Offgrid Express costs less than $100 ($80 to be exact, or £60 and approximately AU$110) but offers a beefy 3,000mAh battery that can double your phone's battery life.

If battery cases are too bulky for your liking, or you're happy with the one you currently have, consider an external battery pack. They often provide more power (for less money) than battery cases.

Anker's lipstick-size portable charger is just $10 and provides 3,350mAh -- a bit more than a full charge.

Trianium's case (which retails for $80 or about £60 and AU$105 converted) sports a 3,100mAh capacity, but still manages to stay slim. In addition to juicing up your phone, the battery case adds a layer of protection with a raised edge around the screen.

If you need a lot of extra power, this is your go-to. Zendure's power pack ($55) houses 16,750mAH of extra juice, so you can charge your phone several times without ever looking for an outlet.

Zendure's charger can power two devices at once with a port for small devices (like phones) and another for large devices, like tablets.

Mophie's Juice Pack ($119.95 and £109.95, or about AU$167 converted) is more expensive than Apple's battery case, but it provides way more power. The case sports a 3,300mAh battery, and is charged with a Micro-USB cable.

Lepow solves the annoyance of a bulky battery case by letting you remove the bulk when you don't need it.

It comes in two parts: a case and a battery pack. When you need to charge up, the battery pack latches on magnetically and plugs into your phone's Lightning adapter.

Its capacity is 3,000mAh -- well more than Apple's case -- and a steal at $33.

If you want more protection along with more power, the durable Resurgence Power Case does both. Though it adds more heft to your phone, you'll get that extra peace of mind against everyday bumps and drops.

Part LED flashlight, part charger, the Enerpack ($44) offers 8,000mAh of juice and two charging ports -- one for small devices like smartphones and another for larger devices, like tablets.

This 3.8-ounce case is slim and beats the iPhone's battery case with a 2,400mAh capacity.

The best part? Its price. UNU's battery case can be had for just $35.

Like Lepow's solution, Tylt's two-part juice pack ($80) only adds the bulk when you need it.

Slide the 3,200mAh battery pack on when you need to charge; slide it off when you don't need the extra juice.

Spigen's case ($36) doubles the thickness of your iPhone's size and adds 3,100mAh of extra power.

Like many of the other cases listed here, it requires a headphone adapter and lets you know how much it's charged with an LED bar on the back.

Need more case options beyond battery packs? Here are dozens more of our favorite iPhone 6 and 6S cases.