The Best USB Battery Packs, from Wirecutter

We spent more than 20 hours researching 160 USB battery packs, brought in almost 50 pounds of batteries, and tested them in a specialist lab in Vancouver, British Columbia, all to find the best USB battery pack for any situation. Whether you need a pocketable pack to get through an evening out, a unit to leave in your bag to keep your device going for a busy day of meetings, or plenty of power for a week on the road, we've got you covered.