Some day, somehow, our smartphones will feature batteries that last for days on end without having to be recharged. Today however, you're lucky if you can go 24 hours without charging your smartphone. Whether you have an iPhone or an Android device, you need a portable battery charger in order to ensure that you always have power when you need it. Of course, that doesn't mean you have to spend a lot of money on a portable power pack. Below, you'll find five different top-rated portable battery chargers that will work with any iPhone or Android handset, and each one costs less than $25 including free Prime shipping.

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