You can use power banks with a 10,000mAh battery capacity for charging your smartphone and accessories. With a 10,000mAh power bank, you can fully charge any smartphone at least once. You can fully charge smartphones with a smaller battery, such as most iPhone models, twice. You can easily take this power bank with you anywhere thanks to its small size. If you're away from home for longer, you need more capacity. Almost all power banks have multiple USB ports. So you can charge your smartphone and your smartwatch or e-reader at the same time.