Connect the test clips to battery positive and negative position, check the LED display to know the car battery condition.
Check before Charge - Battery is alive, "OK" to be charged.
Alternator check - Accelerate your engine to 2000 rpm when the green light is lit, charging circuit is ok, while the red light shine means the dynamo supplies no or very little voltage.
Battery check - Indicate the percentage charging in the battery "Full, Middle or Low".
Cranking check - Red light indicates voltage from Alternator over-high.
DO NOT support 24V trucks!