Power Banks. ( Energizer ) Available here. A power bank is a portable device that stores energy to charge other electronic devices. It's designed to be compact and easy to carry, providing a convenient way to recharge your devices when you're away from a power source. With a power bank, you can charge smartphones, tablets, laptops, smartwatches, wireless earbuds, e-readers, Bluetooth speakers, portable gaming consoles, cameras, and even portable lights or fans. Generally speaking, light power banks are easier to carry but have lower power capacity than heavier ones. If you are wondering which power bank you need to charge your iPhone or Galaxy, you should know that an iPhone 16 or the latest Samsung Galaxy has a battery of roughly 3,500 to 4,000 mAh, depending on the exact model.When charging devices with a power bank, it's important to understand that not all the stored energy is transferred to the device. Typically, around 20% of electricity is lost during the charging process due to heat generation and energy conversion inefficiencies. This reduction is common across all power banks, so it's essential to consider when calculating how many times a power bank can fully charge your devices. If you will be charging just your smartphone and a set of headphones, a portable power bank with a capacity of 10,000 mAh is ideal. It will charge your phone twice, or once plus a top-up for your smartwatch, earbuds, or e-reader. If you're a heavy user or need more power on longer trips, a 20,000 mAh power bank will provide around four to five full phone charges, making it a versatile and reliable option for keeping your devices powered throughout the day.