1. Alternator: The alternator is responsible for charging the battery while the engine is running. If the alternator is not working properly, it will not be able to provide enough power to the battery, and the battery will eventually discharge.
2. Voltage Regulator: The voltage regulator controls the amount of voltage that is sent to the battery from the alternator. If the voltage regulator is not working properly, it can cause the battery to be overcharged or undercharged, both of which can damage the battery.
3. Battery Cables: The battery cables connect the battery to the alternator and the starter. If the battery cables are corroded or loose, they can prevent the battery from receiving power from the alternator.
4. Bad Battery: It is also possible that the battery itself is bad. If the battery is old or damaged, it may not be able to hold a charge.
To diagnose the problem, you will need to test the alternator, voltage regulator, and battery cables. If you do not have the tools or knowledge to do this yourself, you can take your car to a qualified mechanic.
