Warning lights
Battery light: a charging system warning
Despite its name, the battery light rarely means the battery is bad. It means the electrical system is not being charged, and the car is running on what the battery has left.
Can I keep driving with this light on?
Battery light: on while driving
High: limit driving, fix within days
The car is running on the battery alone: drive straight to a safe place or a shop, with accessories off.
- Switch off the A/C, heated seats and radio.
- Avoid stopping the engine until you arrive: it may not restart.
- If the steering gets heavy or the temperature rises, the belt may be broken: stop.
49 CFR 571.101 Table 1: electrical charge telltale identified by the battery symbol or the words Volts, Charge or Amp; no color is required. Your owner's manual prevails for your car.
The electrical charge telltale is listed in the federal table of controls and displays, FMVSS 101, identified by a battery symbol or the words "Volts", "Charge" or "Amp"; the standard does not fix its color, and most makers use red. It normally lights for a moment when you switch on the ignition and goes out once the engine runs. If it comes on while driving, the charging system has stopped supplying enough voltage. The alternator may have failed, its drive belt may have slipped or broken, or a connection or fuse in the charging circuit may have opened. The car keeps running on the battery alone, for a time that depends on its charge and on what you have switched on, often minutes rather than hours. If the belt also drives the water pump, the engine can overheat at the same time. Switch off non-essential loads, watch the temperature gauge, and drive directly to a safe place or a shop.
Shop labor rate: a starting estimate for your state
Starting estimate, United States (average)
$110/h
| Average technician wage | $27.13/h |
| National average wage | $27.13/h |
| Multiplier assumed | × 4 |
BLS OEWS, May 2025. The multiplier is our assumption, not a measured rate: shops post their own rates, and dealers often charge more.
Codes, rules and labor data checked by Radif Partners · Editorial policy · Method and sources
What to do on the road
- Switch off the radio, the heater or air conditioning fan, seat heaters and any accessories plugged in. Keep the headlights on if you need them to be seen.
- Watch the temperature gauge. If it rises, the belt that drives the alternator may also drive the water pump; stop before the engine overheats.
- Do not switch the engine off until you are where you want to be: it may not restart.
- Listen for a squeal, which suggests a slipping belt, or a whine or grinding from the alternator.
The usual causes
- A failed alternator: worn brushes, a failed voltage regulator or diode.
- A broken, loose or glazed drive belt, or a failed tensioner.
- Corroded battery terminals or a loose ground cable, which a shop checks first because it is quick.
- A blown fuse in the charging circuit on some vehicles.
How a shop tests it
With the engine running, a charging system usually holds between about 13.5 and 14.8 volts at the battery, depending on the car and temperature. Below that, it is not charging. A load test of the battery and a voltage drop test of the cables complete the picture. Many parts stores offer a free test. The repair labor for an alternator varies widely with access; the rate tool on this page shows the starting labor rate in your state.
Hybrids and start-stop cars
Hybrids and many recent cars with start-stop have no conventional alternator, or a different charging system, and may show the warning as a message. Their 12-volt system is charged from the high-voltage battery through a converter. The owner's manual explains what the warning means there. Compare with the oil pressure light, a warning that calls for an immediate stop.