4) Asus Zenfone 3s Max: Asus Zenfone 3s Max is a battery-centric phone which also uses Asus-patented reverse-charging technology to work as power banks for charging other devices. The phone comes packed with 5000 mAh battery but the downside is, it does not have the fast charging adapter. The device takes 3-3.5 hours to get fully charged. Asus Zenfone 3s Max comes with Android 7.0 Nougat and is priced at Rs 14,999. The smartphone features a 5.2-inch HD display, 1.5 Ghz Mediatek 6750 octa-core processor, 3GB RAM and 32GB storage. The storage is expandable up to 2TB via the dual-hybrid SIM slot. The rear camera is 13MP and the front camera is 8MP. This is a 4G-VoLTE smartphone that supports WiFi, Bluetooth 4.1, GPS for connectivity.