Car Constantly Dead

I left my 03 liberty sitting for a couple weeks and when I went to start the engine, it was completely dead. I hooked up a micro emergency start battery and it did not even see any voltage to start the car. The auto parts store said it was a bad alternator. I changed the alternator and it fired right up. However, after a few days, the battery went completely dead again. I can jump the car and restart for a couple of days, but after that is is completely dead again. Any thoughts? I am thinking bad battery cell although an in-car battery test at the auto parts store showed a good battery. I have removed the battery and will have an out of the car test at the part store. I do not see any obvious phantom battery drain sources.

Your advise is appreciated.

Look for a date code on your battery. A round sticker with a letter and number. Sometimes melted into the side edge of the top plastic piece of the battery. Letter is the month, number is the year.

Sometimes one cell of a battery dies. It'll charge up and show 13 volts but the bad cell will drop quickly and drain the other cells overnight on the bench.

Concurred, just swapped my battery out a couple weeks ago. Showed as fully charged everytime it was tested, but let it sit for 15 - 20 minutes and it'd drop to about 11-11.5 volts, and barely start. New battery (under warranty of course) and no issues

Replaced my 4 year 6 months CRD battery about a month ago...same symptoms as above. Could charge it overnight, start it in the morning and drive around fine..charging at 13.4 volts.

Checked residual draw at standstill by removing one battery lead and putting meter on DC AMPS in series with the battery.

Current draw was about 40 mA which was OK.
Next day battery flat.
Took it to battery center who tested it as bad!

Surface charge - constant problem with vehicle batteries. It looks like it's fully charged, but really doesn't have the oomph behind the initial numbers.

I replaced the battery on my '05 a few months ago and, despite the old battery looking perfect at 12.6v every time I tested it for about 3 years, the Libby now turns over faster and starts faster than it has since I installed the horrible Bosch battery to replace the dead OEM Daimler Chrysler battery - the NAPA Premium I just put in is a much better battery. People seem to love the Bosch High Performance battery, so I must have gotten a lemon. I didn't even bother to warranty it out, it was so bad (5 year warranty).

Anyway, using a meter to check the charge and the charging circuit doesn't necessarily get the whole story. Get a load tester, or have your LAPS do it, and test the battery under load. If it only has a surface charge, the load tester will rat it out.

I'm old-school; I use a voltmeter. One probe goes on a post and the other probe gets dipped in the acid of each cell. Each cell should add two volts and they might if the battery's just been charged. A night on the bench gives honest readings in the morning.

This won't work on newfangled battery types.