The only thing that discharges a battery is current flow.

In your car, take an DC Ammeter and place it in series with your battery
with everything off. You remove the Negative battery clamp and place the ammeter leads on the empty battery terminal and the lead you just took off.

If you see much more than 20 milliamps DC current then you can see why the battery is going west. Things such as a glove box light, or trunk light staying on for three days might kill your battery.

You can remove fuses one by one to see if the fault is on a fused circuit,
and which circuit has the fault. It wont take but a few minutes to find
the problem if it's on a fused circuit, such as the courtesy lights.

Some things are not fused, but will show up with this test.

It's possible to have a fault in the alternator for example, which isn't fused.
So hopefully you determine the fault is on a fused circuit.

Post back with what current flow (DCma) you see at the battery.

The normal low current flow level supports the CPU, the alarm, and the clock, and fluctuates some, around 20 ma is normal.


Bill