How to check your car alternator

In addition to a lit alternator or battery light, a dead battery, a battery that continues to run down or a slowly cranking engine can all be a sign that your alternator is not charging properly.

Instructions

Difficulty: Easy

1. Start the car and turn on the headlights.
2. If the headlights are dim, the alternator is producing very little current and the lights are running off the battery.
3. Rev the engine.
4. If the lights get brighter it means the alternator is producing some current but may not be producing enough at idle to keep the battery properly charged. If the lights have normal brightness and don’t change intensity as the engine is revved, your charging system is functioning normally.