Portable devices like smartphones, tablets and iPods are equipped with built-in rechargeable batteries that always seem to need recharging at the worst moment. When that happens, the search for power can become desperate. Visit any airport terminal or similar venue and you are sure to see masses of power-starved devices -- and their owners -- huddled around every available electrical outlet.
Portable chargers - also called power banks or USB battery packs – eliminate the need to find an outlet while you're on the go. These devices can get a dead smartphone up to half-charged or better in under an hour. When the charger itself runs out of juice, you can recharge it from a powered USB port on a computer or laptop – or, for faster results, plug it directly into a wall outlet. Most portable chargers don't come with an AC power supply, but you can often use the one that came with your mobile device. Some chargers can even continue to provide power to your devices while they're being recharged, a feature called pass-through charging. This can be a real convenience when you're pressed for time and outlets.
Portable chargers are lighter, smaller and more ruggedly built than ever before. Mini power banks the size of a lipstick tube or a stack of three credit cards can fully charge a drained smartphone once or twice over. On the other end of the spectrum are powerful chargers rated at 20,000 mAh or more, which are about as big as a large paperback, weigh around a pound, and can power up to four devices at once. These powerful portable chargers typically cost from $30 to $50, but basic models are available for $20 or less.
A final feature that sets the best portable chargers apart is their lifespan – the number of times they can be recharged and discharged before their own internal batteries give out. The best models include fail-safes to protect them against overcharging, so they won't damage or overheat your devices. Some also include protection against surges, short-circuits, and high temperatures. Finally, a good charger should be backed by a strong warranty, so you can get a replacement if it conks out too soon after purchase.
The best portable chargers pack plenty of power in a small package. They can power up your devices quickly and reliably, and they're easy to use. Many of them offer useful extras like indicator lights and pass-through charging, which will let you recharge the power bank even as it's recharging your mobile device(s). We looked to professional comparison tests from sites like TheWirecutter.com, PC Advisor, GottaBeMobile.com and GadgetViper.com for information about performance and features. User reviews from sites such as Amazon.com and BestBuy.com helped us gauge long-term durability and customer service. We factored in all these results to select our Best Reviewed portable chargers.
If you're looking for a portable charger that you can keep in your bag and use to power multiple devices while you're on the go, our sources say the RAVPower RP-PB19 (Est. $35) is the one to have. This palm-sized slab is a bit too big to slip into a pocket – about 5 by 3.2 by 0.9 inches and 11 ounces in weight – but that extra heft comes with plenty of power. It's rated at 16,700 milliampere-hours (mAh), and tests at The Wirecutter.com found that it could deliver about 11,030 mAh in actual use. According to reviewer Mark Smirinotis, that's "enough to completely charge a tablet with power to spare, or to charge most smartphones five times over."
Better still, this power bank can charge two devices at the same time. It has two ports, one rated at 2.55 A and the other at 2.4 A, and testers at The Wirecutter.com were able to squeeze a total of 4.9 A out of both ports together before the device shut down. That's enough power to charge two iPads simultaneously at top speed. The The RAVPower RP-PB19 power bank also has smart charging technology, so it can automatically sense the ideal level of current for your device and adjust itself accordingly. Pass-through charging isn't advertised as a feature for this portable charger, but owners say they've successfully used the charger in this way.
More than 11,600 owners have reviewed the RAVPower RP-PB19 at Amazon.com, giving it an overall rating of 4.6 stars out of 5. Users say this portable charger works fast, bringing a smartphone from nearly dead to fully charged in under an hour. They also report that with its high capacity, it can recharge that same phone through multiple cycles before it needs to be recharged itself. Other features they appreciate include the LED power indicators and the carrying pouch and assortment of cables that come with the charger. Owners' main complaints are that the portable charger is bulky and heavy and that it takes a long time to recharge itself – anywhere from 8 to 13 hours.
Most owners say the RP-PB19 is well built and durable, but there are a few complaints that it broke down soon after purchase – usually because one or both USB ports stopped working. However, the charger is backed by a 12-month warranty – which you can extend to 18 months if you register the product online – and most users who had problems say RAVPower replaced the damaged unit for free. We saw several reviews that started out negative, but ended with praise for RAVPower's great customer service.
If portability is a top priority – and you don't need to charge two devices at once – you can get good results with the Anker PowerCore 10000 (Est. $25). Marie Brewis of PC Advisor describes this as "an awesome little power bank: tiny in size, but with heaps of power and insanely fast charging speeds." It's significantly smaller than the RAVPower RP-PB19, measuring just 3.6 by 2.4 by 0.9 inches – about the size of a deck of cards – and it weighs only 6 ounces. Its rated power is 10,000 mAh, but Brewis says it's roughly 60 to 70 percent efficient, so you'll only get 6,000 to 7,000 mAh out of it in practice. However, that's still enough to provide four recharges for an iPhone or a low-end Android phone. For "flagship Android" devices, with around 3,000 mAh battery capacity, the Anker is good for two charges.
Like the RAVPower, the Anker portable charger has LED indicator lights, smart charging, and an auto-on function that starts it up as soon as you plug in your device. However, unlike the RAVPower, it has only a single USB port, which can output power at up to 2.4 A. Also, unlike the RAVPower, it can't be used for pass-through charging. It comes with a USB-to-micro-USB cable, but no carrying case, and it's backed by an 18-month warranty.
We found over 3,200 reviews for the Anker PowerCore 10000 at Amazon.com, with a remarkable overall rating of 4.8 stars out of 5. Owners love its compact size and say that it works fast, charging their devices from dead to full in 60 to 90 minutes. Like the RAVPower, the Anker gets a few complaints from owners whose devices were defective, but these are countered by praise for Anker's helpful customer service.
Mini portable chargers are external battery packs that can easily slip into a pocket or hang on a keychain. At this size, their batteries aren't large, typically, providing between 1,000 mAh and 3,000 mAh of capacity. However, that's enough to boost the charge of a dying cellphone, or even a smartphone or tablet, at the end of a long day, even if it can't get the device back to full capacity.
In this category, the lipstick-sized Anker 2nd Generation Astro Mini (Est. $11) is a top choice. "Not only is this portable charger extremely efficient, it's easily portable, intelligent and pretty good looking," Brewis says. Cory Gunther of GottaBeMobile.com also includes the Astro Mini in a roundup of the 14 best portable chargers, saying it's great option for those who "truly want a portable charger."
Unlike the cheap, unreliable lipstick chargers you can pick up at the checkout counter, this one's the real deal. It sports a rugged anodized aluminum case and packs a full 3,200 mAh of power. Moreover, according to Brewis, its superior battery cells and chips can manage a remarkable 90 percent efficiency, so that 3,200 mAh capacity translates to 2,880 mAh in real life – enough to bring a smartphone back to full charge. Unlike some lipstick chargers, the Astro Mini is brainy enough to sense your device's recharge rate and match it automatically. Brewis calls this "an undeniably cool feature that meant the Anker was able to charge even our iPad mini, and iPads are notorious for being fussy about the devices from which they charge."
Because this portable charger is so tiny, it can't match the functionality of the larger chargers listed above. It has no auto-on or auto-off capability, and no LED indicators to show how much power you have left. It also can't support pass-through charging. However, at a mere $11, it's hard to beat for value – especially when backed by Anker's 18-month warranty.
The basic version of the Anker 2nd Generation Astro Mini has only a handful of reviews at Amazon.com. However, a package deal that includes a Lightning cable, the Anker 2nd Gen Astro Mini + Lightning Cable (Est. $25) has over 450 reviews with an overall rating of 4.5 stars out of 5. Frequent fliers particularly love its compact size and ability to charge up their phones in about an hour. However, the charger itself is slow to recharge, taking 4 hours or longer for most users. Quality control also seems to be an issue, as we saw several complaints from owners who received defective devices. Anker's customer service typically replaced them promptly, but a few users say the replacements they received didn't work either.
High-capacity portable chargers are ideal for travelers who constantly use several personal electronics devices, but are not always near an outlet. These mega-chargers certainly aren't the smallest of the bunch, but they pack the power needed to charge smartphones, music players, tablets and more – even two or more at a time.
The RAVPower Ace Series RP-PB052 (Est. $40) receives more positive reviews from professionals and users than any other portable charger we've seen. The Wirecutter.com recommends this as the best high-capacity charger to stow in your luggage on a trip. You wouldn't want to carry it every day, as it's a sturdy brick weighing 14.4 ounces and measuring 6.5 by 2.8 by 0.9 inches. However, for long family trips – especially camping trips away from an electrical outlet – it's just the ticket. It has a whopping 22,000 mAh of max power, and The Wirecutter.com's tests found this works out to 15,560 mAh in real-world use. That's enough to keep a smartphone fully charged for a week out in the woods.
If you have multiple devices to charge, that's where the RP-PB052 really shines. It boasts three charging ports and can put out power from all of them at a combined 5.5 A. According to TheWirecutter.com's Smirinotis, that's enough to "charge three large devices at a solid clip or two full-size tablets at full speed." However, Brewis cautions in PC Advisor that charging slows down somewhat when all three ports are in use. The power bank starts charging automatically when you plug in a device (or three) and uses smart charging to deliver the right amount of power to all of them.
LED indicators on the body let you know when the power bank is running out of juice – and you should heed them, because once it's empty, it takes quite a while to recharge. Although Smirinotis says it "recharges faster than any other pack we tried," Brewis reports that it takes 10 to 11 hours to get the charger back to full power using the micro-USB input. Fortunately, users who have tested the power bank report that it's possible to use pass-through power while it's recharging, even though RAVPower doesn't advertise this feature. Reviewer Simon Tunnard of Gadget Viper.com is impressed that the power bank "was able to charge both my boys' Fire HD Tablets faster than they could deplete them."
Tunnard gives the RAVPower RP-PB052 one of the top slots in Gadget Viper.com's list of the best high-capacity power banks. He's particularly impressed with its wealth of safety features, which include "protection against high temperatures, short circuits, surges and over charging." He also notes that its "improved high-density Li-Polymer batteries" not only boost its efficiency but also give it an estimated lifespan of 500 charge cycles. "If you were to recharge this power bank once a fortnight," he says, "it could last you a whopping 20 years." RAVPower backs up this claim with a lifetime warranty.
The 2,650-plus owners who have reviewed this portable charger at Amazon.com give it an overall rating of 4.5 stars out of 5. They say they can get an incredible number of charges out of this device, keeping multiple devices going for a week or more. They also love the accessories that come with the charger, including a carrying pouch, two good USB cables, and an AC power cable for charging. Its main drawbacks are its size and long recharge time. There are a few complaints about durability – but RAVPower's customer support responded to all of these with an offer to replace the power bank.
If the RAVPower RP-PB052 is unavailable, the Anker PowerCore 20100 (Est. $40) is a good substitute. At GottaBeMobile.com, Gunther says this is the charger he turns to for long trips or for charging multiple devices. With 20,100 mAh of rated capacity, he says, this portable charger can provide a good five or six recharges for most smartphones – enough to get him through a whole week without an outlet. In tests at The Wirecutter.com, this Anker portable charger produces just over 60 Wh of power before conking out. That's not nearly as impressive as the RAVPower's 78.92 Wh, but it's still a nice reservoir of juice, which it can dispense at a total of 5.2 A across its two power ports. However, unlike the RAVPower, the Anker doesn't offer pass-through charging.
The Anker PowerCore 20100 receives more than 8,475 reviews from owners at Amazon.com, and an overall rating of 4.7 stars out of 5. Owners say it charges up their devices fast, and they can get five to seven full charges out of it before it runs dry. Once it does, however, it needs 8 to 10 hours to recharge. A few users complain that the power bank either broke down after a few weeks of use or didn't seem to deliver as much power as Anker claimed it would. However, most of them add that Anker's customer service is wonderful and was quick to replace the faulty devices under the 18-month warranty.
Although there are lots of portable chargers on the market, there aren't as many professional reviews from highly reputable tech sites as one would expect. The best reviews we've seen are at TheWirecutter.com and Britain's PC Advisor, which provide detailed information based on hands-on testing. We also found some useful professional reviews at GottaBeMobile.com and GadgetViper.com. User reviews -- and there are thousands of them at sites like Amazon.com and BestBuy.com -- add to the picture as well, providing feedback on issues like reliability and support that expert reviewers often can't address.