I just replaced my battery fot the second time in two years. my alternator ws replaced last year. i took it to merchant's to test the alternator and they said it was kicking out 14.6 but the battery was the issue. i bought a new battery and it ran fne for five days, now i just tried to start up the car and all i get is clicks. i did the old fashioned alernator test and pulled the battery cables off before the battery went dead and the car shut straight off, but the mechanics are saying the alternators is fine. what else could be killing the battery?? any help would be appreciated.
Battery Keeps Dying
- Thread starter remogaggi
- Start date
joegr
Dedicated LVC Member
That old fashioned test is a good way to damage a lot of the electronics on modern cars. You may get away with it once or twice, but I wouldn't take the risk. It leads to flaky little things like unexplained power drains.
Let's narrow this down some. First, if you don't have a digital DMM with at least a 10 A DC current range, get one.
Charge up the battery and start the car. Measure the voltage while the car is running. It should stay between 13V and 15V. (14.2 to 14.4 is ideal). If not, your alternator is failing or the wiring to it is bad.
Assuming the alternator was okay, then you are left with two possibilities. (1) Your battery has an internal fault and is self-discharging rapidly. (2) Your car has an excess power drain when it is off.
Disconnect the battery (while it is still well charged), and leave it that way for however long it usually takes for it to go dead. Reconnect and try to start the car. If it starts, then the car is the problem, if not, then the battery is the problem.
Report what happens, and we can go over the next steps (if it is the car).
Let's narrow this down some. First, if you don't have a digital DMM with at least a 10 A DC current range, get one.
Charge up the battery and start the car. Measure the voltage while the car is running. It should stay between 13V and 15V. (14.2 to 14.4 is ideal). If not, your alternator is failing or the wiring to it is bad.
Assuming the alternator was okay, then you are left with two possibilities. (1) Your battery has an internal fault and is self-discharging rapidly. (2) Your car has an excess power drain when it is off.
Disconnect the battery (while it is still well charged), and leave it that way for however long it usually takes for it to go dead. Reconnect and try to start the car. If it starts, then the car is the problem, if not, then the battery is the problem.
Report what happens, and we can go over the next steps (if it is the car).
ok, i let the battery stay disconnected for about twelve hours and reconnected it like you said, the car started right up. i can tell when the battery is gone dead because it will be harder to start. could it be possible that the automatic headlights are causing the problem, i keep them on auto everyday. could that be staying on when i cut off the vehicle?? anyway i'll await ur response. people are teling me its the alternator but i don't think so. i tested the alternator when i put the battery back in, it read 13.7. my battery charger has an alternator tester and it read that the alternator was good.
joegr
Dedicated LVC Member
Okay, take the key out and close the doors. Leave the headlights on auto. Open the trunk and disconnect the positive battery lead. Put your DMM on the 10A DC current range. Plug the probes into the meter as indicated on the front of the meter for the 10A current range. Somehow attach the black lead to the positive cable that you disconnected. Now somehow attach the red lead to the positive battery post. (Maybe with some duct tape or something.)
The meter will probably read a couple of amps or so and the trunk light will be on. Now wait for about 30/40 minutes. The trunk light will be off now. See what the meter reads now. Anything over 0.05 A is a problem. How much does it read?
If it is over 0.05 A, start pulling the fuses in the fuse box in the battery compartment. Which (if any) fuse being pulled causes the current to go way down? If pulling any fuses causes the current to go back up, then you will need to wait 30 more minutes before trying the next fuse.
When you think you've found the right fuse, put the others back, wait 30 minutes, and verify that the current is still less than 0.05A. If so, identify that fuse and we'll see where to go from there.
The meter will probably read a couple of amps or so and the trunk light will be on. Now wait for about 30/40 minutes. The trunk light will be off now. See what the meter reads now. Anything over 0.05 A is a problem. How much does it read?
If it is over 0.05 A, start pulling the fuses in the fuse box in the battery compartment. Which (if any) fuse being pulled causes the current to go way down? If pulling any fuses causes the current to go back up, then you will need to wait 30 more minutes before trying the next fuse.
When you think you've found the right fuse, put the others back, wait 30 minutes, and verify that the current is still less than 0.05A. If so, identify that fuse and we'll see where to go from there.
lincoln_1999
Active LVC Member
Maybe your keyless keypad is draining your battery . Is your keyless keypad working ??
Stick with Joegr's diagnostics, he's right on track to isolate the problem. If it seems like a pain in the ass, it is. Electrical problems are a pain, but they are also fairly simple to correct once you know the problem.
In all likelihood it's probably something stupid, like a door switch or something, that's not terribly expensive to fix.
Good luck!
Oh, if you have a set of jumper cables, you could probably use those to connect the battery to the meter, just be careful what you set it against.
In all likelihood it's probably something stupid, like a door switch or something, that's not terribly expensive to fix.
Good luck!
Oh, if you have a set of jumper cables, you could probably use those to connect the battery to the meter, just be careful what you set it against.