Tonny 12V Car battery monitor, It shows very clear the status of your car's battery, It protects the engine computer and 12-volt accessories from damaging surges when jump starting or recharging. The LCD screen displays the measured voltage with a bar graph to indicate battery charge level quickly identify the battery's charge status.<br><br><b>Parts Diagram :</b><br><b>Pivoting Head</b> - Pivots for easy viewing and angle adjustment<br><b>Voltage Reading</b>- Refer to battery state of charge chart for voltage reading levels<br><b>Charge Graph</b> - Displays the measured voltage to indicate battery charge level <br><b>Red LED</b> - Indicates bad test result<br>Alternator test :15.11-16V <br>Battery test : 11.99 - 0V<br><b>Yellow LED</b> – Indicates potential problem or low voltage <br>Alternator test : 14.51 - 15.1V<br>Battery test : 12.00 - 12.60V <br><b>Green LED</b> - Indicates good test result <br>Alternator test : 13.51V -14.5V <br> Battery test : 12.61 - 13.5V