* Old battery: Batteries typically last for around 3-5 years, so if the battery in your Subaru is older than that, it may be time for a replacement.
* Electrical problem: There could be an electrical problem in your Subaru that is causing the battery to drain. This could be anything from a faulty alternator to a short in the wiring.
* Parasitic draw: A parasitic draw is when something in your Subaru is using power even when the car is turned off. This could be anything from a glove compartment light that doesn't turn off to a faulty radio.
To troubleshoot the problem, you can start by checking the battery. If the battery is old, it may be time for a replacement. You can also check the alternator by starting the car and then measuring the voltage at the battery terminals. If the voltage is below 14 volts, the alternator may not be working properly.
If you are not able to find the source of the problem, you can take your Subaru to a mechanic for diagnosis.
