Anyone who uses a smartphone knows the importance of carrying a backup battery pack. But try searching for one on Amazon, say, and you’re likely to feel overwhelmed by the vast number of options. Besides the various charging specs, ports, and even cables you have to consider, there are a ton of competing brands. How are you supposed to know which ones actually live up to their promise?  

We’ve done the legwork for you, evaluating a wide range of power banks from different manufacturers, costing different prices, and some offering unique features. Our testing is extensive, too, subjecting the packs to real-world usage (read about our testing process in detail below). Our picks below reflect a range of needs. (You might also be interested in our our roundup of USB car chargers if you spend a lot of time in transit.)

Updated 2/1/22 to include our review of the EcoFlow Delta Mini Portable Power Station. More than your typical pocket charger, the Delta Mini is a hefty power source for extended time off the grid, like camping or in an emergency. It’s pricey, but it buys you the assurance that all your gear can be charged.

How we test

Determining whether a power bank lives up to a company’s promise entails more than simply connecting it to a phone and charging. Testing battery packs is done over weeks, not days, and requires extra equipment in order to ensure the batteries work as expected.

1. Upon receiving each battery pack, it’s fully charged, using indicator lights as a means to track charge level.

2. Then to track efficiency, we use an AVHzY USB Power Meter in tandem with a DROK Micro Load Tester.

As we use the DROK load tester to drain the pack of power, we are able to test against a battery’s stated maximum current, and verify that proper shutdown mechanisms are in place should something go wrong during a charging session (such as a device drawing over the maximum amps).

By using the AVHzY USB Power Meter, we are able to monitor volts and amps, total power throughput, and total amount of time to deplete a battery from full to empty. The meter can create an Excel spreadsheet of the entire process for future reference.

3. Next, we recharged the battery, this time using the AVHzY to track it and chart the amount of time it takes to reach full charge.

The AVHzY meter solves a shortcoming we had with our previous method with the PortaPow. Previously we had to use a GoPro camera to track each battery through its charge cycle, as the PortaPow monitor would continue to collect data after the battery was fully charged (trickle charging is normal, and unfortunately interferes with our testing).

If a battery was capable of charging through USB-C, we use that instead of Micro-USB.

4. The AVHzY also has a feature built in that checks a charging port for all of its supported charging standards. We are able to run that test and get an instant readout to confirm support for QC 3.0, for example, without needing to have compatible phones or devices on hand.

Power source and cables
All of our tests were conducted using the same wall adapter and, when possible, USB-C or Micro-USB cable. This was done to eliminate any discrepancies with wall adapters and cable throughput.

What to look for in a portable power bank

Without fancy testing equipment, you never truly know if you’re getting what you paid for with a battery pack. Vendors, especially in Amazon listings, like to throw around a lot of terms and certifications.

Here are a few tips to help you make a decision:

• For those with a compatible device, make sure the battery pack is Quick Charge 2.0, 3.0, or PD certified. Depending on your smartphone, this can make a big difference in performance. If you own a QC 2.0 device, however, ask yourself if paying extra for a QC 3.0 capable pack is worth it.
• Don’t put 100 percent confidence in a company’s claims of a pack being able to charge, say, a Galaxy S8 or iPhone X six times over. Battery capacity and efficiency varies based on a number of factors. Read this Macworld report on USB-C packs to learn more about batteries and capacity.
• Look at the specs of the battery, and ensure that its input isn’t limited to slow charging such as 5V/1A. The faster the input, the faster your battery pack rechargers, the faster you’re ready to hit the road.