The best power banks for 2024 Buying Guide

I considered buying an iPhone 15, but realized I’m perfectly happy with my iPhone 11. Only thing is, the battery doesn’t last like it once did and often needs a top-off before the day’s done. That became nerve-wrackingly clear on work trip in which I found myself navigating a new city with three percent left on my phone. Luckily, I had a power bank. These battery packs also come in handy when you’re on your laptop at the coffee shop, or when you head out on a long hike or bike ride. Larger portable chargers let you set up a mobile command center out in the field, charging a tablet, refilling a camera, even powering LED lights. There’s endless stream of portable batteries on the market, with new models coming out often, so we’ve tested —and continue to test — multiple options so you can find the best power bank for you.

What to look for in a portable battery pack

Battery type

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 carryon the next time you fly as they aren’t allowed in checked baggage.

Capacity

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.

Ports

While the tech world is (thankfully) moving towards USB-C charging 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 charging 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 charging 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 charging 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 delivery 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 likedAnker’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 charging cables will make sure you’re not wasting time with connections that limit your potential power transfer.

Design

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 portable power stations 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.