: 1278x900 px
: June 28, 2018
If the battery terminals are clean and tight, then the next item to check is drive belt tension. If the belt which drives the alternator is too loose, then the alternator will not produce enough electrical current to keep up with demand. Many modern vehicles utilize a single belt which drives the alternator and other accessories. This system usually also has an automatic belt tensioner which always maintains correct tension and is not adjustable. If your vehicle uses a wide, multigrooved or so-called "Serpentine" belt to drive the alternator, then it likely also has an automatic tensioning device.
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.