3PCS Keenstone UDI U818A WiFi FPV U845A U945 WiFi Rc Quadcopter Drone 3.7V 400mah Battery With Charger (U818A) 6 Pcs of Morpilot 3.7V 550mAh 25C LiPO Battery for UDI U817 U817C U817A U818A WLtoys Quadcopter V959 V969 V979 V989 V999 V929 V949 V212 V222 , no modification necessary.Not compatible for UDI U818A WiFi FPV. Deliver powerful output with 4 high performance Mosfets.Intelligent chipset provides overcharge/overdisacharge protection.Patented design to avoid crash of your drones. More PUNCH and ROBUST performance due to its higher current output and power Single Battery Weight: 16g.Search "KU818" to find the battery charger Single Battery Size (Max.): 58.0 x 17.5 x 7.8mm