WipKviey Mini T16 Blue Drone Indoor Flight

flight battery used: Rage RC 1s 400mah that comes stock with Rage RC Micro T-28 Trojan
venue: my church sanctuary
Flight time: 7 minutes
flying style: stayed on lowest speed mode of its controller the whole time
starting chg: like 4.14-4.15v according to my lipo voltage checker
after flight chg: 3.81-3.82v according to my lipo voltage checker and 3.69-3.7v according to my digital multimeter