Whether you call them battery packs, power banks or portable chargers, these accessories do one thing well: charge your devices when you can’t find an open outlet. Small enough to fit in a day pack and sturdy enough to live at the bottom of your carry on, battery packs can charge your smartphone, tablet, laptop or even all three at once, depending on the size of the battery. What size you’ll need, and any extra features you may find useful, will largely depend on the devices you plan on charging up. With so many of these accessories on the market right now, we tested out a bunch to see which are worth your money.
Spigen ArcHybrid Mag$60
Best for a partial charge on an Android
Anker 511 Power Bank$30
Best low capacity
BioLite Charge 40 PD$60
Best medium capacity
Otterbox Fast Charge 15,000mAh$45
Best high capacity
Anker 737 Power Bank$130
Best mobile command center
Mophie Powerstation Pro XL$200
What to look for in a portable battery pack
Nearly every rechargeable power bank you can buy (and most portable devices) contain a lithium-ion battery. These beat other current battery types in terms of size-to-charge capacity, and have even increased in energy density by eight fold in the past 14 years. They also don’t suffer from a memory effect (where battery life deteriorates due to partial charges).
One drawback you may have heard is the possibility of lithium ion batteries catching fire. To limit the danger, battery packs require internal mechanisms to limit things like voltage and pressure. While you should still make sure a battery isn’t exposed to unnecessary stress like excessive heat, damage from drops or operating in freezing weather, battery packs are considered safe enough to bring on an airplane. According to the TSA, external batteries rated at 100Wh or less (which all of our recommendations are) can fly with you – just make sure you stash them in your carry on as they aren’t allowed in checked baggage.
Power bank manufacturers almost always list a battery’s capacity in milliamp hours, or mAh. Smaller batteries, say those that can charge a smartphone to between 50 and 75 percent, tend to have a 5,000mAh capacity. Larger batteries that can recharge laptops and tablets, or give phones multiple charges, can exceed 25,000mAh. Unsurprisingly, the prices on most batteries goes up as capacity increases, and since batteries are physical storage units, size and weight go up with capacity as well. If you want more power, be prepared to spend more and carry around a heavier brick.
You might think that a 10,000mAh power bank could charge a 5,000mAh phone to 100 percent twice, but that’s not the case. In addition to simple energy loss through heat dissipation, factors like voltage conversion also bring down the amount of juice that makes it into your phone. Most manufacturers list how many charges a battery can give a certain smartphone. In our tests, 10,000mAh of battery pack capacity translated to roughly 5,800mAh of device charge. 20,000mAh chargers delivered around 11,250mAh to a device, and 25,000mAh banks translated to about 16,200mAh of charge. That’s an average efficiency rate of around 60 percent.
While the tech world is (thankfully) moving towards USB-C as the standard, it’s still a mixed bag in the power bank world. All of our picks have at least one USB-C port and a few also have a USB-A port or two. Newer Android smartphones charge via USB-C, iPhones still use the Lightning port, but the latest tablets (including current generation iPads) and newer laptops are typically powered up via USB-C.
When a battery pack has more than one port, they usually serve different functions. You’ll typically see at least one port labeled “in/out,” which means you can use it to both charge the bank and charge your device. While USB-A ports can power up smartphones and other small devices, they can’t charge larger devices. Plus, they aren’t as fast as USB-C ports overall. That’s something to keep in mind when you’re deciding which ports and cables to use to connect your phone to the pack.
There’s even more variation among USB-C ports themselves, with different ports on the same device supporting different power transfer rates. What that means in practical terms is an iPhone will charge just fine plugged into a power bank’s 18W port. But to properly charge, say, a MacBook or similar laptop, it’ll need the extra juice supplied by a 100W port (which larger power banks can offer). Power banks with more than one port can also charge multiple devices at the same time, but speeds and the overall charge delivered will be lower.
You’ll also want to consider your cable. For anything larger than a smartphone (and to access fast-charging capabilities) you’ll want to use USB-C ports and cables. But not all cables are created equal, even when they have the same USB-C plugs on the end. If you want power delivered from a 100W USB-C power bank port, you’ll need a 100W-rated USB-C cable. Luckily, power banks capable of delivering 100W tend to include a compatible cable. For any devices that don’t, we’ve tried and liked Anker’s 100W USB-C cable. For smaller devices, we used this 60W cable from Nimble and we don’t recommend bothering with cables under 60W. For around $20, higher-capacity cables will make sure you’re not wasting time with connections that limit your potential power transfer.
For the most part, battery packs have a squared-off, brick-like design, though many nod towards aesthetics with attractive finishes and detailing. While that doesn’t affect how they perform, it’s a consideration for something you’ll interact with regularly. Some include extra features like MagSafe compatibility, a built-in wall plug or even a kickstand. Nearly all have some sort of indicator to let you know how much available charge your power bank has left, usually expressed with lighted pips near the power button. Some of the largest banks take that a step further with an LED display indicating a percentage for the remaining battery, which can be helpful if you’re relying on a pack in a mobile office setting or something similar.
How we tested
Before we even put our hands on a battery pack, we did extensive research. We considered brands Engadget reviewers and staff have tried over the years and we checked out customer ratings on retail sites like Amazon and Best Buy. In all, we acquired 14 battery packs, ranging from small wireless banks to large, multi-device batteries.
Here’s the full list:
Apple MagSafe Battery Pack (5000 mAh)
Spigen ArcHybrid Mag (5000mAh)
Anker 521 Magnetic Battery (5000 mAh)
Anker 633 Magnetic Battery (10,000mAh)
Low capacity (≤10,000mAh)
Anker 511 Power Bank (5,000 mAh)
Anker 313 Power Bank (10,000mAh)
Nimble Champ (10,000mAh)
Biolite Charge 40 PD (10,000mAh)
Mid capacity (10,001 - 20,000mAh)
Otterbox Fast Charge (15,000mAh)
Mophie Powerstation Pro (20,000mAh)
Anker 535 PowerCore 20K (20,000mAh)
High capacity (20,001mAh+)
Mophie Powerstation Pro XL (25,000mAh)
Anker 737 Power Bank (25,600 mAh)
Zendure Supertank Pro (26,800mAh)
I tested each battery on an iPhone 14 Plus and a Galaxy S22 Ultra. For the mid- and high-capacity packs, I added an iPad Air (5th generation) to the mix. I only charged one device at a time, even though some are capable of multiple-device charging. I charged from fully depleted to 100 percent (or until the power bank was dead), and didn’t use the device while they charged other than to power them on and enter the unlock code.
For the most part, I used the cable included with each power bank to charge the Galaxy S22 Ultra and the iPad Air. For the iPhone 14 Plus, I used the USB-C to Lighting cable that came with Apple’s phone. In the case of the lower-capacity power banks that didn’t include a cable or included a USB-C to USB-A cable, I used a 60W-rated USB-C to USB-C cable.
For reference, here are the battery capacities of each device we used for testing:
iPhone 14 Plus: 4,325 mAh
Galaxy S22 Ultra: 4,855mAh
iPad Air: 7,729mAh.
I noted the times for each charge and the number of charges each bank provided. I also paid attention to things like ease of use and overall design. Here’s what made the cut:
Best MagSafe-compatible battery: Spigen ArcHybrid Mag
I went into this category expecting Apple’s own MagSafe battery pack to win. And while it performed admirably, charging a dead 14 Plus to about 43 percent in an hour and 45 minutes, Spigen’s ArcHybrid delivered a 56 percent charge in nearly the same amount of time. The ArcHybrid firmly attaches to the MagSafe ring and it’s flush enough that you can easily hold your phone and use it while charging up. Unlike the Apple battery, it includes four indicator lights to help you gauge how much juice the pack itself has left. Considering Spigen’s battery is $30 cheaper than Apple’s, it’s easy to recommend.
Alternatively, Anker’s 633 Magnetic battery delivered a larger charge thanks to its 10,000mAh capacity, boosting the iPhone to 100 percent in three hours with enough left over for an additional 29 percent charge. And while the kickstand feature felt mildly useful, the battery itself was bulky – but that’s understandable for a power bank that’s twice as large as Spigen’s. Ultimately, the ArcHybrid performed better as a quick and convenient way to give a partial charge to your iPhone on the go.
It’s important to note that wireless charging is less efficient than wired. Our tests showed wired battery banks deliver a device charge at around 60 percent efficiency. With the wireless chargers, that rate dropped to an average of 46 percent. Something to keep in mind when weighing the costs, both ecological and monetary, of wasted energy.
Specs: 5000mAh, 7.5W max
Ports: One USB-C in/out
Cable: USB-C to USB-C
Number of charges iPhone: 0.56
Charge time iPhone: 0 to 56% in 1h 43m
Best battery for a partial charge on an Android: Anker 511 Power Bank
Until Android phones get something like MagSafe, a wired connection makes the most sense for on-the-go charges. The Anker 511 Power Bank is a cleverly designed unit about the size and shape of a skinny stick of butter. The battery charged a depleted Galaxy S22 Ultra to 75 percent in a little over an hour, so you’ll be covered if you don’t have long between flights to give your phone a bit more juice. It also has a built-in plug and allows for pass-through charging, which means it can act as a wall adapter if you’re ever stuck with both a dead battery bank and phone, but happen to be near an outlet. It doesn’t come with a cable, though, so you’ll need to provide one that can go from the bank’s single USB-C port to your device.
Specs: 5,000 mAh, 10W max
Ports: One USB-C and wall outlet prongs
Number of charges Galaxy S22 Ultra: 0.75
Charge time Galaxy: 0 to 75% in 1h 7m
Best low capacity battery: BioLite Charge 40 PD
BioLite is probably better known in the outdoor community than the tech world, and it’s fair to say that the Charge 40 PD is geared more towards camping trips than urban commutes. But this battery simply outperformed the others in its category. The rugged, yellow-accented exterior is a refreshing change from the standard shiny black of many tech accessories. It also has a rubberized finish and feels solid enough to handle the bumps and jolts of riding around in a purse or messenger bag all day. It gave both the iPhone and the Galaxy one and a half charges, which means it’s plenty capable of reviving a dead phone a couple of times when you’re out and about.
The Nimble Champ gets an honorary mention here because it’ll also deliver a few reliable fill-ups and comes in a rugged package. It delivered a full charge to the iPhone in two hours plus a 22 percent charge in 16 minutes. It gave the Galaxy a full charge in an hour and 44 minutes, then got the phone from dead to 41 percent in 50 minutes. At the same $60 price point as the BioLite, Nimble gets extra points for being one of the few B-Corp-certified personal tech manufacturers out there, meaning they’ve committed themselves to higher environmental and social standards, and took the time to prove it through B Lab’s certification process.
Specs: 10,000mAh, 18W max
Ports: One in/out USB-C, two USB-A out only
Cable: USB-C to USB-A
Number of charges iPhone 14 Plus: 1.36
Charge time iPhone: 0 to 100% in 1h 50m, 0 to 50% in 36m
Number of charges Galaxy S22 Ultra: 1.33
Charge time Galaxy: 0 to 100% in 1h 33m, 0 to 50% in 45m
Best medium capacity battery: Otterbox Fast Charge
At the medium-capacity level, you can charge multiple devices at once or power up something larger than a phone. The Otterbox Fast Charge power bank only lists 15,000mAh of capacity, but it performed nearly as well as the 20,000mAh batteries while costing about $30 less. Over the month and a half I spent testing battery packs, this was the unit I grabbed the most when my own devices needed a charge. It has a stylish exterior with a gray faux leather finish and copper detailing. A little bigger than a deck of cards and weighing just over 11 ounces, it’s a nice looking accessory that feels solid.
It filled up both smartphones twice, then gave an additional third of a charge each. I introduced the iPad to the mix here and got a full charge plus an extra third. The Otterbox also lost very little charge while sitting dormant, which means if you carry it around on the off chance that you’ll need it, it should have plenty of power when the time comes.
This category may have been the closest to call, as Anker’s 535 Power Core performed slightly better than the Otterbox, but Anker’s price point is higher. That said, if you want a screaming fast charge for your Galaxy phone, grab the 535. It got the Galaxy up to 100 percent three times, taking about an hour each time. It had enough left over for a small nine-percent charge before it finally gave up. While the battery did get pretty warm, it never felt overly hot. That one-hour fill up is the fastest any power bank was able to deliver a charge to the Galaxy, other than Anker’s 737, which shaved off a few minutes, but costs $90 more. I also appreciated the 535’s cool iridescent finish.
Update, 2/13/2023: Anker's 535 Power Core battery, which we mentioned as an alternate medium-capacity option, has been recalled due to a potential fire hazard. If you've purchased the 535 battery pack, the Anker rep we spoke with recommended that you stop using the device and follow the guidelines from the EPA or local agencies to dispose of the battery. Follow this link to learn how to initiate a refund.
Specs: 15,000mAh, 18W max
Ports: One in/out USB-C, one in/out USB-A
Cable: USB-C to USB-A
Number of charges iPhone 14 Plus: 2.33
Charge time iPhone: 0 to 100% in 2h 2m average, and 0% to 33% in 27m
Number of charges Galaxy S22 Ultra: 2.33
Charge time Galaxy: 0 to 100% in 1h 35m and 0 to 37% in 33m
Number of charges iPad Air: 1.31
Charge time iPad: 0 to 100% in 2h 23m and 0% to 31% in 38m
Best high capacity battery: Anker 737 Power Bank
If you want something with a lot of charge that transfers quickly, go for the Anker 737 Power Bank. It was for the most part the fastest bank we tried, capable of delivering the largest amount of charge in the shortest period of time for the iPad and Galaxy. (Anker’s 535 got the iPhone to 100 percent an average of two minutes faster, but didn’t give as many charges.) The 737 fully charged our S22 Ultra three times, with enough left over for another 93 percent charge – and those full charges completed in under an hour on average. That’s on par with outlet charging. The numbers for the iPhone were slightly less staggering, but still impressive, going from zero to full in about an hour and a half. The iPad charged completely twice, and did so in just over two hours, which is also close to that device’s wall-connected charge speeds.
While it’s great for multiple full charges on a given smartphone, I should point out that the 737 has three ports, but only one of those is USB-C. If you want to charge more than one device at a time, you’ll have to use the lower-efficiency USB-A ports for a couple of them. That said, this bank not only costs less than the other high capacity batteries we tried, it also includes a 65W PowerPort fast charger, which goes for $34 on its own.
The design is nothing groundbreaking, with a glossy black exterior and a metallic-looking finish on one side. It weighs a little over a pound and has the same general form as an old school TI-85 graphing calculator. Its single button has eight lighted pips to show you how much charge it has left.
Specs: 25,600mAh, 60W max
Ports: One in/out USB-C, two out only USB-A
Cable: USB-C to USB-C, includes 65W wall adapter
Number of charges iPhone 14 Plus: 3.67
Charge time iPhone: 0 to 100% in 1h 38m average and 0 to 67% in 40m
Number of charges Galaxy S22 Ultra: 3.93
Charge time Galaxy: 0 to 100% in 57m average 0 to 93% in 59m
Number of charges iPad Air: 2.14
Charge time iPad: 0 to 100% in 2h 7m average and 0 to 14% in 13m
Best mobile command center battery: Mophie Powerstation Pro XL
For those who take their work on the road, the Mophie Powerstation Pro XL, with its trio of USB-C ports, is a good pick. It’s capable of charging three devices at once, with a different wattage rating for each port: 100W, 45W and 20W. In practice, that means you could use the ports to charge a laptop, a tablet and a phone simultaneously. To keep the numbers comparable across our testing, I charged one device at a time. Both smartphones juiced up fully three times, with around a third of an additional charge left over. I got about two full charges from the battery on the iPad Air.
The Powerstation XL has the look and feel of a fancy pocketbook with a marled gray fabric exterior that feels nice in the hand and, incidentally, hides stains well. It weighs the same as the Anker 737 (one pound and three ounces) and also has lighted pips to indicate charge levels. There are only four lights, however, which doesn’t give you the most precise insight as to how much charge it's carrying.
Another option, the Zendure Supertank Pro, almost won this category in part because it handles its charge indication with a lighted LED display that shows exactly how much charge remains, expressed as a percentage. With four variable-wattage USB-C ports, a tough exterior and included semi-hard case, it seems tailor made to act as a power source for mobile photoshoots or nomadic offices. The charge speeds were a little slower than the Mophie, but it did manage to give a few more percentage points of charge to the iPad and the Galaxy phone, filing the latter four times. In the end, it came down to price: for $50 more than the Mophie, the Supertank Pro’s speeds and capacity just didn’t edge it out. But if you happen to see the Supertank on sale, snap it up.
Specs: 25,000mAh, 120W max
Ports: One USB-C in/out, two USB-C out only
Cable: USB-C to USB-C
Number of charges iPhone 14 Plus: 3.23
Charge time iPhone: 0 to 100% in 1h 45m average and 23% in 18m
Number of charges Galaxy S22 Ultra: 3.85
Charge time Galaxy: 0 to 100% in 1h 36m and 85% in 1h 12m
Number of charges iPad Air: 2.02
Charge time iPad: 0 to 100% in 2h 16m and 2% in 7m