: 2953x1971 px
: July 7, 2018
If the battery warning light (a light in the shape of a battery symbol) on the dashboard comes on while you're driving, that means the charging system isn't working, but the fault may lie in something other than the battery. The cause of the battery light could be a loose or corroded battery cable or other wire connecting components of the charging system, or it might be a problem with the alternator or voltage regulator. The alternator generates the power that is stored in the battery. If the alternator fails, or the accessory belt that drives the alternator is loose or broken, then you'll end up with a dead battery because the bad alternator isn't recharging the battery.
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.