The first thing to check is if your alternator is charging the battery correctly. Jump start the car and let it run for a while. Get a multi-meter and set it on DC volts. Measure the voltage across the battery terminals while the car is running. It should be somewhere between 13 and 14.5 volts. If it's too low you probably have a problem with your alternator. You can get this checked for free at most auto parts stores like Autozone. If the voltage is too high you may have problem with your voltage regulator. The auto parts stores will also check this for you.
If your charging voltage is ok and you're still having problems with the battery discharging if you don't drive the car for a few days, then you may have a problem with some circuit in the car drawing too much standby current and slowly draining the battery when the car is off. This can be a tricky problem to track down. Start by getting a multi-meter and set it on DC amps so you can measure the current coming out of the battery. Disconnect the positive cable from the battery and hook up the one lead of the meter to the positive battery terminal and the other lead to the cable end that you disconnected. Set the range on the meter so you can see how much current is being drawn out of the battery. Now go to your fuse box. Pull out one fuse at a time and watch the output of the meter. This would be easier to do if you had 2 people, one to pull the fuses and one to watch the meter. If you don't see the current go down when you pull a fuse, reinsert it and try a different one. Keep doing this until you've found the fuse for the circuit that's drawing the excess current. You can probably find a fuse box diagram in your owners manual or on-line. Let's say the offending fuse was for your radio. Now you have a clue where to look for the problem. In this example maybe your radio has gone bad and is drawing more current than it should. I hope this advice helps you out.
PS: Make sure you don't have anything like a cell phone charger plugged into your 12V power jack. They can draw standby current and drain your battery if you don't use the car for a number of days.
Start pulling fuses,until you find the circuit
Then get a wiring diagram and work that circuit
Something is not going to sleep like a module
Check for bad Alternator Diodes
Welcome to FIxYa.com
Check for a drain remove the positive side battery connect a test light clamp end to the battery wire and the pointed end to battery post light will be on. Pull one fuse at a time. When test light :light goes out that is the circuit draining the battery
Regards, Lee Davidian
Thank you for using FixYa,com.
473 views
Usually answered in minutes!
×