Just replaced the battery, and the alternator. Thought I had a parasitic drain so I would take off the negative battery cable when the car would sit overnight. Car ran fine for awhile doing that, however one day went to the store and by the time I got out the battery was dead again. Now this happened to me once before so I just took back the battery and got a new one. Ran great again for another month. Then same thing, went to the store and again the battery was dead when I came out. Now it only seemed to happen at night when I had to turn the head lights on. Cables look good, belt is tight. Any ideas???

 

how's you charging voltage?

 

Is reading around 11.56V

 

now....I am having the battery drainage problem. Just purchased this car, I see many of my car's problems in this forum. It is very informative. ....(Hope my car starts for work in the morning, I have been jumping it for a week now. My mechanic replaced the computer, he thought that was the problem. I seem to have the door locks &/ trunk open & close on their own? strange.....any help with draining battery???? OMG...spent almost 5000 trying to fix this thing....PLEASE HELP Thanks all

 

"Is reading around 11.56V."

Srogers, the charging voltage should be around 14v. 11.6v is much too low to charge the battery.

 

With the key on (car not running) make sure the battery light comes on and you have battery voltage on the small red wire terminal on the back of the alternator.

 

This is the suggestion that no one really likes but is a quick easy way to see if your alternator is working. With the car running disconnect the positive cable from the battery if the car quits the alternator is bad. Another way is to check the battery voltage before starting the engine and then start the engine and check the voltage at the battery with the engine running. You should have more than 12 volts at the battery with the engine running. Alternators will have an output of 13.5-14.5 volts

 

what is draining your battery is every electrical system in your car that requires voltage when your car is running...your alternator is toast!

 

so that's the voltage while engine is running? if so, that's much too low. something is wrong.
either yourself, or another, have checked the voltage regulator at the alternator.

and make sure the alternator is connected properly.

and even if that's the voltage at the battery with engine off, that too low.

on a side note, if you had your new alternator installed by a shop, do not do business with them again.