Originally Posted by tsac
The pack you have is what is used but if you want to try, there are a few internet videos that show how to replace the battery. There are a few others on the internet. I would watch a few to be sure of how to do it.
The problem with the typical external power bank (I use one from the brand RAVPower that does Quick Charge 2.0) is that it's too large and heavy to carry around in all situations. That's why I'm looking for a Mophie Juice Pack or equivalent that fits on the phone as a CASE:
I also have neither the time, nor the steadiness of hands, to want to mess with replacing the internal battery on my phone.