: 1280x720 px
: July 4, 2018
The charging system will normally consist of two major components: An Alternator which actually supplies the necessary electrical current in order to charge the battery, and a Voltage Regulator. The latter insures that the system does not overcharge the battery, and that the correct system voltage is maintained. Most vehicles produced within the last 20-30 years use a voltage regulator which is an integral part of the alternator itself. This article assumes that your vehicle uses this type of alternator.
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.