I notice that my car battery would die after a day, so I changed the alternator thinking it's that, that didn't work. Then I changed the starter and it would drive around for maybe 3 days after being charged (10 miles per day).
But car dies after a day or two. It'll let me drive around, then after I turn it off, The next day it'll be dead. Also, I check the alternator by removing the negative cable from the battery when the car is on, and it stays running.