How to Respond When Your Car's Battery Light Goes On

The battery light is misnamed: It doesn't go on when the battery is low. The battery light will go on only if the alternator is not charging the battery.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Car Alternator
• Car Batteries

1. Do not panic - you have some time. You don't have to pull over right away. But don't ignore this light! You have anywhere from a half-hour to a day or even longer, depending on how much charge is left in the battery.

2. Turn off all unnecessary electrical accessories, such as the radio, heater, defroster headlights and windshield wipers.

3. Avoid using the horn, turn signals, flashers, dome light and power windows.

4. Avoid turning the engine off and on. Starting your car uses more of the battery's charge than anything else.

5. Drive to your auto repair shop if you can. Ask your mechanic to do an alternator output test to check if the alternator is charging.

6. Take the following steps if you can't visit the mechanic right away.

7. Turn the engine off and open the hood.

8. Look for whitish/bluish powdery corrosion on the battery cable ends. Clean with a wire brush if it's in evidence.

9. Make sure the battery cable ends are tight. You shouldn't be able to turn them at all.

10. Check the negative battery cable end. Make sure it's tight and secure at both ends.

11. Check the alternator belt (see "Check Your Engine Belts," under Related eHows). A loose belt will cause the alternator to undercharge and trip the battery light.

12. Make sure all the connections at the back of the alternator are secure.

Tips & Warnings

• Don't assume that the light is broken. It's possible, but unlikely.
• If you ignore the battery light and keep on driving, eventually your engine will sputter and stall. There will be no more electricity in the battery and there will be no spark to ignite the gasoline in the cylinders. The car will not crank or start when you turn the key, and the radio and lights will not work. How long this will take is anybody's guess. A car with a battery light on may indicate an undercharging alternator, in which case the car will work just fine for days. A car with a completely failed alternator and an older battery may only have an hour or two left.

Who Can Help Sponsored

[kimmay]

on 5/22/2009 I was driving to work today and i was getting off the exit ramp and i noticed my battery light came on, so i turned of my radio and unplugged my cell phone car charger and the light went off. when i was driving home from work it started fine and when i had low accellaration it came on but when i was on the o nhighway the light didnt come on. What does this mean?

[jaz01]

on 5/3/2009 Hi!! hope anyone can help me!!In january I bought a new battery for my ford focus. About two days ago the Battery Light is starting to go on and of. I can start the vehicle with no problem, radio work just fine and everything else also.Please if someone thinks is the alternator, please let me know!! This vehicle is the one that keeps me going, from work, school, my kid!!

[cyclonus002]

on 2/10/2009 I have a question..Yesterday my car failed to start (2000 Chevy Blazer)noticed my battery power was low so I thought the alternator was out..took it out and got it tested. It was bad so I bought a new one and installed it but car stiil would'nt start. Is it possible the battery has some power but not enough to start the car? The engine turns but just won't kick on..

[mmmrs]

on 1/20/2009 Your ABS light is Anti-Lock Brake System (at least in my Accord). And if it does come on, your normal braking function is fine...you can drive without your anti-lock brakes. You just need to be super-careful in rain/snow. My ABS light came on (when I needed my rotors replaced) and all my mechanic had to do was dust off the metallic dust from the brakes off the sensor and it hasn't come on since!

[Delmarco]

on 7/16/2008 Only problem is the check battery light is still on so I'm replacing the Alternator. But it could also only be that I need to reset the check battery light(BMWs can be complicated like that). Either way, it is important to know that it could only be a "faulty battery" and not the Alternator. So troubleshoot the battery before chucking your Alternator because most batteries are free to replace (if still under warranty) or only $100 to buy new, while Alternators are significantly more money to replace. And I'm sure most Mechanics will tell you to replace the Alternator before checking what is wrong. Then they can bill you alot of money for unnecessary labour and parts.