: 2048x1536 px
: June 23, 2018
The test procedure is quite simple. Set the meter to read DC volts, and set the correct range if needed. Some meters will select the correct range automatically. Nearly all meters will come with instructions on how to set them to read DC volts. Next, connect the meter across the vehicle battery, positive (+) to positive (+) and negative (-) to negative (-). With the engine running at a moderate idle - say 1200 to 1500 RPM, the meter should read approximately 13.8 to 14.8 volts and be steady. If the reading is substantially outside these figures and all other items mentioned have been tested and verified good, then the alternator is likely defective.
If the battery light is on and you're still driving the car, turn off as many electrical accessories as you can, such as the stereo, air conditioning or heater, and avoid using electrical controls such as power windows. Reducing the amount of electricity the car is consuming will increase the distance you can drive before the battery is discharged. Get to a mechanic as quickly as possible, and have the battery, wires and charging system checked out to find the cause of your problem and what you need to repair or replace.