Battery Light is on.

[itreflop117]

Yea, haven't been on here awhile. The problem is exactly how the title states. When I turn my car on all the way the battery light stays on. However, whenever I accelerate it turns off and stays off. Then when I slow down to a lower rpm it turns back on.

I figured I should buy a new battery just to make sure. ( I needed a new one anyway.) I bought a Duralast Gold. So I went out driving again and the same thing happens. I accelerate the light turns off. When I get to a lower rpm and at idle it stays on.

My question to you guys is this: what causes this light to stay on? My dad thinks it's an alternator problem where it's not charging the battery enough at idle/low rpms OR there is a short somewhere in the car...

ANY info/tips would be awesome. Thanks guys for your time. I really appreciate it.

[Kiwi-Corolla]

Could possibly be a problem with the alternator, but the first thing I'd check is the alternator belt. Make sure that it's tensioned correctly and isn't worn. Then check that the wiring harness for the alternator is secured tightly, and not burnt or cut in any way. If everything checks out ok then it's time to test it with a multimeter.

With the engine off, connect the multimeter to the battery terminals and make sure you have at least 12 volts. Now start the engine and check the battery voltage again. It should be between 13.5 to 15.1 volts. Now turn on the headlights. The voltage should drop and then come back up if the charging system is working properly.

I'd recommend taking the car to an auto electrician and getting the problem professionally diagnosed. Most places do the diagnosis for free. They have all the right equipment to do proper tests (such as an amperage output test) on the charging system. Good luck!

[itreflop117]

Originally Posted by Kiwi-Corolla

Could possibly be a problem with the alternator, but the first thing I'd check is the alternator belt. Make sure that it's tensioned correctly and isn't worn. Then check that the wiring harness for the alternator is secured tightly, and not burnt or cut in any way. If everything checks out ok then it's time to test it with a multimeter.

With the engine off, connect the multimeter to the battery terminals and make sure you have at least 12 volts. Now start the engine and check the battery voltage again. It should be between 13.5 to 15.1 volts. Now turn on the headlights. The voltage should drop and then come back up if the charging system is working properly.

I'd recommend taking the car to an auto electrician and getting the problem professionally diagnosed. Most places do the diagnosis for free. They have all the right equipment to do proper tests (such as an amperage output test) on the charging system. Good luck!

ahh i'm glad i came here for help. you always have the right thing to do man. i appreciate it thanks!!! i'll update tomorrow if anything.. my dad is gonna replace the alternator for me. =DDD

[speedy25]

Most probable reason is the regulator/rectifier is going bad. Most people dont know how to replace or how to find the part so they install a new alternator.

Using a voltmeter confirm that you dont have 13.2 to 14v when the engine is above idle.

-SP

[96coroll]

I would recommend what the guys have said here. I've down it before it's not very difficult to test the battery at idle. My first impression would be the alternator.

This sort of problem has happened to my bosses ford E - 150, the exact same symptoms.

Good luck, shouldn't be much of a problem to fix.

[REN69]

It is the alternator, there are plenty of threads around pointing at the alternator when the battery and and sometimes the brake light come on at the same time.

[94PrizmDD]

You can also take it to Advance or Autozone. They charge and test your battery for free. Then you can rule out the battery if its good.

[Dannyboy1277]

I had a similar problem but all they had to do is adjust the alternator belt.

[Steelballz]

had the problem on my car before, somehow the nut holding the thick wire on the alternator came a bit loose...tightened it and it was fine again.
if this doesnt work, put in a new alternator