Likes an htc the fast charging should help because you cannot ad a car battery to a phone !
Another option for better battery
The Xiaomi Mi Max 2 weighs 211 grams, and measures 174.1x88.7x7.6mm. It runs on a 5300mAh battery that supports Qualcomm Quick Charge 3.0 (0 to 68 percent charge in 1 hour), and is rated to deliver up to 57 hours of talk time, 18 hours of video playback time, and 31 days of standby time.
the features of the phone are wonderful!
Tech is advancing fast
yeah amazing fast.