- Defective battery connections. Check the battery connections and ensure they are clean, tight, and free from corrosion.
- Faulty wiring or connections. Inspect the wiring between the battery and the alternator, as well as the ground connection between the battery and the chassis. Ensure all connections are secure and free from damage.
- Bad alternator. Even though you replaced the alternator, it's possible that the new one is defective.
- Battery: The battery may be faulty and unable to hold a charge, even with a new alternator.
- Other electrical issues: There may be other electrical problems in the vehicle that are preventing the battery from charging properly, such as a faulty voltage regulator or a short circuit.
