A fully charged car battery should have a resting voltage of about 12.6 volts when the engine is off. If your SUV battery is showing 12.01 volts, it’s below the optimal level, which indicates it’s not fully charged but not necessarily bad¹. It could be a sign that the battery is aging or that it has been drained due to lights being left on or other electrical devices running while the engine is off.

To determine if the alternator is bad, you can check the battery voltage while the engine is running. The voltage should increase to between 13.7 and 14.7 volts as the alternator charges the battery². If the voltage does not increase when the engine is running, it could indicate a problem with the alternator.

Here are some steps to test the alternator:

1. Start the engine and let it idle.
2. Use a multimeter to check the voltage at the battery terminals.
3. The voltage should read between 13.7 and 14.7 volts².

If the voltage remains around 12 volts or less while the engine is running, the alternator may not be charging the battery properly. In this case, it’s advisable to have a professional mechanic perform a thorough diagnosis to confirm the issue and recommend the appropriate repairs. Remember, diagnosing car issues can be complex, and it’s often best to consult with a professional for accurate troubleshooting and repair.