AUTO Battery Tester: The battery tester can test all 6V 12V 24V100-2000 CCA car batteries, support 2Ah-220Ah (need to enter the corresponding CCA value on the battery), including the AGM flat plate. (AGM tablet battery), AGM spiral (AGM coil battery), GEL and EFB batteries, battery analyzer for cars trucks SUV ATV boats motorcycles vehicle etc. Quick and Accurate: Quickly determine and accurately the overall health of the battery. And the Battery Load Analyzer lets you test batteries both in-vehicle and out-of-vehicle, even test dead batteries. Simply connect the tester clips to the battery, then it will turn on and ready to test and analyze the battery. Show Batteries Data: Provides basic battery parameters such as voltage, internal resistance, cold cranking amperage and AH capacity, battery health and charging status, shows you professional advice to replace or charge the battery. Plug and Play: It is simple to use, just connect the battery tester clip to the car battery correctly and it can start working whether the battery is in the vehicle or out of the vehicle, whether discharged battery can be tested. With a large LCD display with white backlight and contrast adjustment, shows test results directly. Easy to carry and worry-free for outings or business trips. Reverse Connection Protection: Red connects to battery positive and black connects to battery negative. battery, the battery tester works normally. if the clip is not properly tightened, the screen will flicker, the clip is properly tightened, the screen will not flicker. Tips: 1.You must turn off the engine to test. 2. This device does not need a built-in battery. 3. When testing a discharged battery, please charge the battery.