Power issues with my G37

I got my 08 G37 last January. And when I got I knew there was still that the car had trouble starting if it sat more than 3-4 days. So I got a new battery. I couldn’t find the draw and The Infiniti dealership was no help but everything was relatively fine. Now usually when that car doesn’t start after letting it sit what it would do was crank 3 times then put me in ON mode so I would have to jump it with my jump pack. Now on the day before the big snowstorm, I pressed the button Key the car clicked and then turned off. (It sounded like if you were to unplug something while it was running. Like a powering down sound.) Fully dead. Push start didn’t work. No door lights. Couldn’t lock the car. And when I opened the door the windows rolled down like the battery had been disconnected. So I put the jump pack on like usual and the car started like usual. But when I turned it off again the same problem. So I called my mechanic friend and he said to get a multimeter and test the battery while it’s off. And I did and it read 13.1 while idle and at 2500 RPMs. He said it was most likely the alternator dying. So I went to O’Reilys and did an alternator test. Which said it was bad. Don’t pass the regulator test or something. So I left the car sitting for 4 days I went to go start it and it started first try. So now I’m confused about what it could be.

My running theory is that I jumped the battery too many times which caused it to be damaged and then kill the alternator.

Other people with similar issues on the G37 Forums say it is the starter or loose connector

Does anybody have any insight before I spent $75 on a new alternator?

TL: DR I having intermittent no crank no start issues as well as a parasitic draw and a dying battery

 

If the test said your alternator was bad you should replace it regardless. If it were the starter the, car would start up either very weakly or not at all.