Yesterday i replaced the battery and drove it around the block at the battery light turned off. Today i drove across town and now it wont turn off . I was maybe thinking it was the alternator but im not sure. So what do you guys think it might be??

 

If your battery is bad, the battery light won't light up. It only lights up if the alternator is not charging the battery, so I would say it's the alternator. Go back and retrieve your battery because it could be perfectly fine.

 

the other one wouldnt take a charge so that one was bad ...but if the alternator is bad then thats what made my old battery die. so when the battery light turns on it means its not charging the battery then right?

 

Did you test the old battery? If the alternator is bad, then the battery will not charge. The battery will continue to discharge until it dies, but that doesn't mean the battery is bad. To have both the battery AND the alternator go out at the same time is possible, but highly unlikely.

 

so was the light on before the old battery died? or did the old battery die, and then you replaced it, and now your getting the battery light?

The light just means the alternator output voltage is outside a specified range, it's either overcharging or undercharging. It will not come on simply because the battery is low. The warning light is connected to the alternator itself, it is not connected to the battery. It only monitors the alternator output voltage.

Most likely you have a bad alternator. check though to make sure the connector on the back of the alternator is firmly attached, it's the plastic one with one or two wire plug that goes in the back or the alternator, not the lead that goes to the battery, althought that one is imprtant too obviously... if that connector is lose, or unplugged that would cause the light to come on, I've had that happen, everything was fine, the plug just came off... I don't think that's your case though, as you had a battery die...

You can check with a digital volt/ohm meter, with the engine off you should be between 11.8 and 12.5 volts on the battery. with the engine running you should be between 13 and 14.4 volts, it should never read more than 14.4 volts. If it is less than 13 with the engine running your alternator is not charging. any parts stor can do that same check for you and should not charge you for it... or you could even go ahead and pull the alternator off and have them bench test it.

 

i'll check the connections for the alternator tomorrow but the old battery was not taking a charge so the alternator slowly killed iti guess.Now i got a new one and now ive noticed that my dash lights are dim and it made it throw a CEL because the rpms were jumpimg and the CEL was for the idle control so i think the alternator is on its last limb keepin the car on but if i cant get it to workA new one it is