AKASO 3.7V 850mAh 4 Pack Lipo Battery with 4 in 1 Battery Charger for AKASO K88 2.4GHz 4 CH 6 Axis Gyro RC Quadcopter It will give more punch and robust performance due to its higher current output and power. Charging 4 batteries at one time. Batteries equiped with Protection Board for safe charging and using. Replacement part 3.7V 850mAh battery for AKASO K88. Replacement part 3.7V 850mAh battery for AKASO K88. Replacement part 3.7V 850mAh battery for AKASO K88.