Hey everyone! Ill make this quick, in my firebird, i have a new alternator thats 8 months old, battery thats 4 months old. Everything was fine until the other day, i go to my car and there was no power. I havent started it like 2 weeks tho. I tested the battery and got 3 volts. Jump started it, runs fine. Turn it off, next day, dead. Then i took a jumpstart battery and charged the car battery over night, in the morning, 10 volts. Later on in the day, 4v. Last night, i boosted it, ran it for 10 mins, turned it off, little power when trying to start it back. Looks like the battery isnt holding its charge. I still have the warranty on it. Any suggestions? Thanks.

 

Whats the voltage at the alternator and at the positive battery terminal while the car is running?

Also, does your battery have a warranty because I'd just swap that to rule it out.

 

if i remember correctly, i think it was 13. But that might of been while the jump-battery was hooked up. Im going to the store tomorrow to get a replacement. But I dont wanna replace something thats still good...Or ill just have them test it at the store.

 

The first thing you will need to do is get a full charge into the battery usually takes 18 or so hours on a charger. If the battery isn't fully charged you might as well beat your head with a hammer cause it will be next to impossible to find a definate problem, unless you just want to replace everything till it works. Running the engine for 10 minutes will not do much other than work your alternator to death a little at a time. After the battery is fully charged do a parasitic drain test, since it sat for two weeks something could be powered on and draining the battery.

Challenge yourself to learn and diagnose a problem ACCURATELY instead of throwing parts at something, it will save you a ton of green over the long haul

 

Thanks! Well i had the jump battery charge the car battery over night, and in the morning, the jumper battery had no charge. Maybe it the car battery fully charged to 13v and slowly went down to 10? How do I do a parasitic drain test?

 

There is actually a couple ways. The easiest way is to disconnect the Pos cable at the battery and put a test light between the battery terminal and cable. A draw should show up by lighting the test light. If the light is on start removing fuses one at a time until the light goes out and that will tell you the circuit causing the draw.

The more effective way IMO is to use a ammeter in place of the test light and look for about 50 milli amps or less, and follow the same procedure to isolate the problem circuit.

 

Ahh, sounds simple enough, ill give it a try tonite.

 

Here is an update. I still think the battery is losing its charge on its own. Today, I had the battery out of the car, hooked it up to a booster battery, once the booster battery died, i disconencted it. I tested the car battery and it had 12 v. Left it alone, 1 hr later, i tested it and it had 10v. I just checked it now and it has 8v. Is this battery a goner?

 

if , and i would return the battery . before you leave the store , check and make sure all cells are full of electrolyte . sounds like you got a bum battery . if you still have a problem you can rule out the battery .

 

Yup I can return it, I have the reciept and its still under warrenty. Im going to do one last charge tonite by hooking up jumper booster to ac outlet and battery to jumper booster.