If your vehicle is showing battery warning light stays on while driving, here are the most likely causes and the parts you'll need to fix each one.
The alternator generates electricity to run the vehicle's electronics and charge the battery while driving. When its internal components wear out, the vehicle runs solely on battery power, triggering the warning light.
The serpentine belt physically spins the alternator pulley. If the belt snaps, stretches excessively, or the tensioner fails, the alternator stops spinning and stops generating power.
Corrosion or loose connections at the battery prevent the alternator's charge from reaching the battery. This is a frequent installation error if the battery was recently replaced and the terminals were not properly tightened.
If the battery has an internal short or a completely dead cell, it may refuse to accept a charge from the alternator, which can cause the charging system warning light to illuminate.
A blown high-amp main fuse will completely sever the electrical connection between the alternator and the battery. This often happens if the vehicle was recently jump-started incorrectly (reverse polarity).