So I'm trying to find out if i have a bad alternator cause i had to jump my car yesterday. The battery is still good but i think the alternator is either not charging the battery or its draining the battery. Checked the battery voltage level this morning and it was low at 12.3. What do you guys think is the main cause?

 

Yep, a bad alternator can absolutely drain your battery. The engine ends up getting it's spark from the battery instead of the alternator.

 

Check the battery voltage when the car is running, it should be close to 14 volts. This is not a perfect test, but if the alternator is only producing 12.5-13.0 volts it is probably the problem.

 

except that a parasitic draw usually comes from a bad HFL unit. which is commonly the root of a drained battery in the TL's

 

HFL parasitic draw does not kill a battery overnight. Most people that have HFL draw don't even know it because they drive the car every day. Read his post again, and see what he asked.

 

if the alternator was bad wouldn't the red battery light be illuminated on his dashboard?

 

it killed my battery overnight. just saying.

 

OP doesnt even know that. He is just throwing what could be the culprit. In OP's case, the HFL could be the culprit, but I do agree with you to check the voltage on the battery while runing first before going any further.