Originally Posted by Atomicmachine
This anker is quite expensive. I want something btw very cheap and very fast to charge.
That Anker is at a sale price on Amazon, but even at it's non sale price that will be about the price of these external battery packs.
But the nice thing about the S4 is the swappable battery. Unless you are going to be away from any charging source for days at a time, a spare battery or two is the perfect solution as you won't be tethered to a cable and a huge heavy brick at the end of it that you have to carry around.