The phone is backed by a 3,000 mAh battery with support for fast charging technology. (indianexpress.com)
Like the Moto C Plus, this huge battery should come with support for fast charging technology or else, it will take ages to charge from 0 - 100 %. (nashvillechatterclass.com)
There's also support for fast charging, which should make it easier to cope with the average battery life of the S6. (androidauthority.com)