What does the battery warning light mean?
The battery-shaped light usually means the charging system isn't keeping up, most often a failing alternator, a worn or broken serpentine belt, or a loose battery connection. The car is running on battery power alone and may only go a short distance before it stalls. Turn off accessories and head straight to a shop or somewhere safe.
What the light is really watching
The battery light monitors the charging system: the alternator, its belt and the wiring between them and the battery. When the engine is running, the alternator should supply the car's electrical needs and recharge the battery. When it doesn't, the light comes on and the car starts draining the battery.
Common causes
- Failing alternator, the most common cause on higher-mileage cars
- Worn, loose or broken serpentine belt
- Corroded or loose battery terminals
- A blown fuse or bad connection in the charging circuit
- Oil leaking onto the alternator from a valve cover gasket above it, which can ruin it
What to do
- Reduce the load: turn off the A/C or heat, seat heaters, rear defrost and the stereo.
- Don't turn the car off unless you're somewhere you can stay; it may not restart.
- Watch the temperature gauge. If it climbs, the belt may be gone. Pull over.
- Get the charging system tested. We test the battery, alternator output and wiring so only the failed part gets replaced.
Hybrid owners: a dead 12-volt battery on a hybrid shows up differently. See hybrid no-starts.
From drivers who came to us
My car died yesterday… they were so kind and helped me out by installing an alternator and I was on the road again.
My Lexus CT 200H was in dying need of a new battery after nine years with over 146K miles… They got my car up and running by replacing a new starter battery and rear shocks since they were leaking by the end of the day.
Excerpts from verified customer reviews on Yelp.
More questions
How long can I drive with the battery light on?
It varies, from a few minutes to about an hour, depending on the battery's charge and how much electrical load you're using. Don't count on getting far.
Does the battery light mean I need a new battery?
Not usually. It means the system that charges the battery has a problem. A battery test and charging-system test together tell you which part is at fault.
What if the belt broke?
On many cars, the same serpentine belt drives the water pump and power steering. If it breaks, the engine can overheat and steering gets heavy. Stop and have it towed.