The voltage monitor is used to detect 1S~8S lithium batteries and automatically detect the voltage of each cell lithium battery and total voltage. Supports reverse connection protection. It allows you to work anywhere in the understanding of the state of your battery so your battery will not overcharge and over discharge or cause damage. When the voltage drops below the set value the buzzer sounded the red LED flashes; default setting is 3.3V press the button to change the voltage setting automatically save the user's current settings. 1 Lithium battery detection for 1S~8S; 2 Voltage detection accuracy: +/- 0.01V. 3 Pack voltage display range: 0.5V~4.5V; 4 Total voltage display range: 0.5V~36V; 5 1S test mode voltage range: 3.7V~30V; 6 Low voltage buzzer alarm mode 2S~8S; 7 Alarm Voltage Range: OFF~2.7~3.8V; 8 Digital tube size is 1.02 inches