1) Travel-card Charger A truly pocket-sized battery
This is still the most reliable credit-card-sized battery, and a staff favorite years after we first recommended it. The TravelCard can give a smartphone like an iPhone 7 or Galaxy S8 about half a full charge, it’s only 5 mm thick, and it has an integrated Lightning or Micro-USB cable.
If you need the absolute smallest battery to keep your phone going through the end of the day when you can’t get to an outlet, the TravelCard Charger is the most convenient and reliable option. A little longer and wider than a credit card, and roughly three times as thick, the TravelCard stands out from other small batteries because it has two integrated cables: one with a standard USB-A plug to recharge the battery itself, and one with either a Micro-USB or Lightning-connector plug (depending on which TravelCard version you buy) to charge your device. Because you don’t need to carry any cables, there’s nothing extra to forget, and the TravelCard is always ready to go. It’s light and well-made, with cables that fit securely without jamming or falling out—a real problem with some of the cheapest credit-card-size batteries. Since this model’s announcement in 2014, several Wire cutter staffers have been personally using the TravelCard with positive results.
That said, even the best batteries at this size have limitations. To preserve battery longevity and avoid heat buildup, they’re limited to relatively slow input and output charge speeds. The TravelCard is similar to competitors here, discharging and recharging at about 1 amp. The Lithium-card from Linear-flux is the only standout of the small batteries we’ve tested, able to put out up to 2 A, closer to batteries in the larger categories. But the Lithium-card has about 20 percent less capacity than our pick, and since you’ll likely be using your phone while charging it with something this size, faster charging speed isn’t the top priority.
Dollar for dollar, the capacities of packs this small are as unimpressive as the charging speeds. The Travel-card averaged 1,048 mAh (3.8 Wh) in our tests; while that’s enough capacity for it to add 30 to 50 percent of a full charge to most smartphones, it pales in comparison to our top pick in the everyday-use category, which offers five times the capacity for a lower price. Even among credit-card-size batteries, some models eke out a few more mAh than the Travel-card. For example, the Flux Portable Charger provided only about 70 percent of its promised capacity, but that’s still double the capacity of the Travel-card. (That said, the Flux is closer in size to an index card than a credit card, so it’s not as pocket able as the Travel-card and is much less capable than our everyday pick, which is thicker but narrower.) The Incipio off GRID 1500, similar in size and price to the TravelCard, provided a slightly higher capacity as well, but the TravelCard is still the better choice because of its integrated USB cable for charging itself: An extra 100 mAh probably won’t make a huge difference in how you use a battery, but never needing an extra cable is more than just a convenience—it’s a relief.
2) Jackery Bolt For everyday carry
The integrated Micro-USB and Lightning-connector cables make it convenient to carry every day, for every device. The aluminum body is the size of a bar of soap, and the Bolt has enough power to charge a midsize smartphone twice.
If you can make just a little more room in your pocket or bag, the Jackery Bolt packs a lot of value into a battery the size of a bar of soap. The Bolt was the only model we tested that hit every item on our wish-list: fast output, three different ways to charge devices, sturdy materials, and enough capacity to charge most smartphones twice over. Though it’s a few dollars more than many batteries this size, you get more for that extra money.
The Jackery Bolt (left) has built-in Micro-USB and Lightning cables so you don’t need anything else on the go. The Anker Fusion (right) has a built-in power plug, which means you don’t need a wall charger but you still need to bring cables with you.
We’re big fans of having an integrated device cable on an everyday battery pack—when running out the door with a pile of batteries to choose from, we’ll take the one with built-in cables every time. But many companies sell one version with a Micro-USB plug and a different version with a Lightning-connector plug, making you choose which one to buy. Even if you get the “right” one, a Lightning-only pack can leave you stuck when you need to charge a device other than an iPhone (say, a camera, e-reader, tablet, or Bluetooth headphones), while a Micro-USB version won’t charge Apple devices. With both cables on the Bolt, you truly have nothing extra to bring along.
The Bolt’s maximum combined output is 2.7 A, and it has a standard USB port that can put out all of that at once—it offers the fastest speed of any small pack we tested—so you have the option of using longer or svelter cables if necessary. Cable size matters, and the chunky cables on the Bolt might cause problems if you use tight cases on your devices. If you do, or if you’ll never need a Lightning cable, our runner-up pick might be the right choice for you.
The Bolt has enough capacity to charge small smartphones twice and larger models at least once. In our tests, it averaged 20.06 Wh (3.99 Ah) of discharged capacity at a 1 A rate. The more expensive Goal Zero Flip 30 beat it handily, with 25.55 Wh (5.20 Ah), but in addition to the higher price, the Flip 30 lacks the integrated device cables that make our picks so convenient.
The biggest downside to the Bolt is the thickness of the housing around the connectors. Though nice and sturdy, the connectors are too bulky to work with cases that have a small opening for the charging port. For example, none of the integrated-cable packs we tried would work with the Otter Box Defender case we had on an iPhone 6s. During testing, we also noticed that while the Bolt is itself pocket-able, the length and orientation of its charging cables make it difficult to slip in your pocket while charging your phone—the battery’s longer dimension ends up positioned perpendicular to the phone’s.
3) Tronsmart Presto 10000 PBT10 For Quick Charge–compatible devices
The Presto is the best one-size-fits-all battery pack if your Android device supports QC 3.0 and you need faster charging. It’s about the size of most midsize smartphones, but it has enough capacity to recharge such a phone about three times.
Huge Battery Size
Quick Charge 3.0
If you’re looking for a power bank capable of charging your Quick Charge 3.0 Android device, the Tronsmart Presto 10000 PBT10 is the best all-around battery pack available. It can charge most smartphones about three times, has an extra port for charging a second device, and recharges itself at the faster QC 3.0 speeds. Though our other picks provide useful extras like integrated charging cables, as well as more value when it comes to capacity per dollar, a Quick Charge 3.0 power bank like the Presto 10000 PBT10 can charge a compatible device from zero to 70 percent in about 30 minutes.
The Presto 10000 PBT10 is smaller and lighter than the first power banks available with Quick Charge 3.0 in 2016, including the larger Anker Power Core 20000 with Quick Charge 3.0, our previous pick (since replaced by the Anker Power Core Speed 20000, which has the same dimensions). Anker’s battery is still a good choice if you need the massive capacity, but the Presto 10000 PBT10 is about 65 percent the size and much easier to carry every day—it’s about the size and shape of a midsize smartphone. Anker and Aukey both make packs that are competitive with our pick, but both are shorter and thicker, so it’s harder to slide them into a tight pocket as most people are bound to do at some point with an everyday power bank.
Despite the slim shape of the Presto 10000 PBT10, it offers two charging ports—other models we tested have just one. Only one of the ports is capable of QC 3.0 speeds (easily identified by the green plastic), while the other one charges at the standard USB full speed of 2.4 A. In our tests, both ports could charge devices simultaneously without one limiting the output of the other.
The best Quick Charge power banks also recharge with the faster QC 3.0 standard using traditional Micro-USB cables, and all three of the top packs we tested did just that. We clocked the Tronsmart Presto 10000 PBT10 as recharging at 17 W, compared with the 18 W maximum, when it started from empty. But all the packs we tried were significantly slower when charging from a non-QC power source. The Presto charged at just 7.5 W, though that’s the same as the pack from Anker and faster than the Aukey pack (less than 4 W). If you’re going to use a Quick Charge pack like this, be sure to use a Quick Charge power source or you’ll be waiting a long time. (We don’t currently have picks for Quick Charge 3.0 wall chargers, but iClever and Anker both make compatible versions of our favorite single- and multi-port chargers.)
Tronsmart’s power bank did slightly better than the competition when we tested the available capacity too. Over three discharges, the pack averaged about 35.2 Wh (9,500 mAh), nearly 98 percent of the promised capacity. That’s a big jump from discharge averages in the mid–80 percent range for the competition and represents an extra quarter of a charge for most smartphones. While numbers in the 80s are common and not worth dismissal by themselves, when battery packs like the Presto 10000 PBT10 discharge nearly their whole capacity in testing, we consider it exceptional.
Anker is well-known for excellent customer support, via email or phone. While researching the Tronsmart, we anonymously contacted that company’s email-only support with a problem to test response time. A representative responded five hours later with some troubleshooting tips, plus instructions for how to initiate an exchange if we couldn’t resolve our problem. While phone support is always a plus, Tronsmart’s prompt and detailed email support left us feeling confident in our pick.