DONZO® POWER battery with NFC for Samsung Galaxy S4 GT-I9500 IV / GT-I9505 LTE with 5800 mAh Li-Ion incl battery cover -. (Electronics)
The battery is much more powerful than the "normal" batteries. However, the phone is now thick and does not fit in my example, belt pouch. But in order to better be accessible, which is a great alternative.