Watching your phone or tablet steadily run out of juice when you're nowhere near a power outlet is stressful. Fortunately, there's no shortage of third-party backup batteries. And they come in every size and capacity (and price range) to keep your device going when your battery icon starts to dip in the red. And it doesn't just end there. Some batteries are equipped with features like fast charging, built-in cables, LED flashlights—even the ability to jump-start your car.
With so many options to choose from, how do you know which battery is right for you? Read on for the most important points to consider, as well as the best battery packs we've tested.
Size and Capacity
Generally speaking, the bigger the battery, the higher the capacity. Batteries that fit comfortably in your pocket are typically good for a full phone charge or two, while anything designed to keep you going all day is going to require a bag or a purse.
On the pocket-friendly front, the RadioShack Lipstick Portable Power Bank is a tiny, 2.4-ounce tube you won't have trouble fitting in even the tightest skinny jeans. But it only holds 2,200mAh of power, which isn't quite enough for a full phone charge. The Ventev Powercell is shaped more like a pocket protector, and provides a bit more charge, at 3,000mAh.
Higher-capacity batteries may not fit in your pants, but can still be stowed in a jacket pocket. The Anker PowerCore 10000, for instance, packs a generous 10,000mAh (good for about three full phone charges) in a 7.0-ounce slab you can carry with little difficulty.
If you're planning on being off the grid for an extended period, the 30,000mAh Aukey Portable Charger can charge the standard phone about 10 times. But it's also roughly the size of a laptop power brick and will need to be carried in a bag or suitcase.
Input and Output Ports
The type of port (or ports) a battery has determines not only whether it is compatible with the devices you want to charge, but also charging speed. At a minimum, most battery packs will have a micro USB port for input and a USB-A port for output.
USB-C allows you to charge faster, and can be found in phones like the Google Pixel and the ZTE Axon 7. Both the Mophie Powerstation USB-C and Monoprice Select Series have USB-C ports for input and output (USB-C cables are reversible).
Lightning is a proprietary Apple technology, so companies need to pay Apple when they use it; that makes it a bit less common to find. The Aukey Portable Charger has a Lightning input for charging the battery itself, while the PhoneSuit Journey All-In-One features a built-in Lightning cable for charging your iPhone or iPad.
Fast Charging
Another factor to consider is how fast the battery pack can charge your phone. The output of a battery is measured in voltage and amperage. Amperage (or current) is the amount of electricity flowing from the battery to the connected device, while voltage is the amount of potential energy. Multiplying volts by amps gives you wattage, the measure of total power. In order to make a device charge faster, most manufacturers either vary the voltage or boost the amperage in order to increase the total wattage.
Standard USB 3.0 ports output at a level of 5V/0.9A. Fast charging starts at 5V/2-2.4A, which you'll find in the Mophie Powerstations (2.1A), for instance. Mophie supports a generic level of fast charging, not tied to any particular standard.
The two main fast charging standards you're likely to encounter are Samsung's Adaptive Fast Charging and Qualcomm's Quick Charge 3.0. Both work in a similar manner, by increasing voltage rather than amperage. As you might imagine, Samsung's Fast Charging only works with certain Samsung devices, while Qualcomm Quick Charge 3.0 requires that your device has a compatible Snapdragon chipset. These standards allow you to charge supported phones to 50 percent capacity in 30 minutes, which is especially great when you need power in a pinch.
Keep in mind, your phone will only take in as much power as its charging circuit is designed for, so even if you have it plugged into a 5V/2A battery, if it's only able to handle 5V/1A, that's the rate it will charge at. Also, iPhones don't support any type of fast charging.
Pass-Through and Wireless Charging
There are a couple of other aspects to consider before selecting a backup battery. Pass-through charging lets you charge devices connected to the battery, while the battery itself is also being charged. If both your phone and backup battery are running on empty, this is a very useful feature.
Wireless charging, while cool, has yet to really take off. Qi is the dominant standard, and it's largely limited to some Samsung phones or protective cases with built-in wireless charging capabilities. That said, if you do want a battery pack capable of wireless charging, there are options out there. The Mophie Charge Force Powerstation, for instance, is a rubberized black slab that supports Qi wireless charging. And if you use a Mophie wireless charging case with it, like the Juice Pack Air for iPhone 7, a magnetic connection holds your phone in place.
Before buying a battery, make sure to decide which features are most important to you. To help make things easier, we've included all of them in the chart above, so you know what you're getting at a glance. Depending on your needs, you can go wrong with any of options listed here.
Featured in This Roundup
Anker PowerCore 10000 With Quick Charge 3.0
$35.99
%displayPrice% at %seller% The Anker PowerCore 10000 is an affordable, compact backup battery that supports Qualcomm's Quick Charge 3.0 standard and can keep your phone running for an entire day of nonstop use. Read the full review ››-
Aukey Portable Charger With Quick Charge 3.0 And Lightning
$62.99
%displayPrice% at %seller% The massive Aukey Portable Charger backup battery has a Lightning port and Quick Charge 3.0 support to power up just about any mobile device as quickly as possible, for days on end. Read the full review ›› -
Mophie Charge Force Powerstation
$99.95
%displayPrice% at %seller% The Qi-enabled Mophie Charge Force Powerstation battery pack can wirelessly charge your supported phones and tablets. Read the full review ›› -
Mophie Powerstation USB-C
$99.95
%displayPrice% at %seller% The Powerstation USB-C backup battery from Mophie offers a solid dose of extra power and USB-C charging, but it's relatively pricey. Read the full review ›› -
PhoneSuit Journey All-In-One Charger
$59.99
%displayPrice% at %seller% The PhoneSuit Journey All-In-One Charger is a compact backup battery with built-in charging cables for Android and Apple phones, and even plugs into wall outlets, making it an ideal travel companion. Read the full review ›› -
RadioShack 12-Volt Pocket Jump Starter/Power Bank
$79.99
%displayPrice% at %seller% The RadioShack 12-Volt Pocket Jump Starter/Power Bank is a unique backup battery that can do everything from charge your phone to jump-start your car, but its relatively large size and small capacity give it a niche appeal. Read the full review ›› -
RadioShack Lipstick Portable Power Bank
$19.99
%displayPrice% at %seller% The RadioShack Lipstick Portable Power Bank is a small, lightweight, affordable backup battery that provides a few extra hours of charge when you're on the go. Read the full review ›› -
Monoprice Select Series USB-C Power Bank
$24.99
%displayPrice% at %seller% The Monoprice Select Series Power Bank promises USB-C compatibility at an affordable price, but using it is far more complicated than it should be. Read the full review ›› -
Samsung Fast Charge Battery Pack
$69.99
%displayPrice% at %seller% The Fast Charge Battery Pack is a sleek backup battery with fast charging benefits for Samsung phone owners, but more capacious options abound. Read the full review ›› -
Ventev Powercell 3015
$34.99
%displayPrice% at %seller% The Ventev Powercell 3015 is a compact backup battery that's easy to slip in your pocket, but its small size limits you to a single phone charge. Read the full review ››
