1-8 Cell LiPo Digital Battery Voltage Checker w/ Warning Alarm Buzzer for DJI Quadcopter For testing 1S-8S LiPo / Li-ion / LiMn / Li-Fe Low voltage warning; Low voltage alarm mode for 2-8S; Alarm set value range (V): 2.7-3.8; Press the black key can change the voltage settings and save Voltage detection precision (V): +/- 0.01; Unit voltage display range (V): 0.5-4.5; Total voltage display range (V): 0.5-36; 1S test mode voltage range (V): 3.7-30 Simply connect the balancing plug on the LiPo battery to the battery tester making sure you align the black wire on the plug with the '-' on the tester. If you have a 3 cell battery you will only have 4 wires. One is ground. Ground is black, align the black with the '-' sign on the tester Package included:- 1S-8S Battery Checker x 1