Well, maybe. The battery actually tests fine.
Here's what I've got: Roommates 2009 Kia Rio, no problems, all the sudden will not start after coming out of a store. The car had been sitting maybe 15 miutes, the lights were not on, etc. Car would try to crank, but didn't have enough change to keep turning over then engine. Subsequent attempts led to the tick of death where the solenoid just buzzes.
A friendly passerby jump started the car. It still turned slowly, but did start. It runs fine with no warning lights.
Upon getting it home, I had the battery tested at the autoparts place. Two different auto places said the battery tested good, and just needed a bit of a charge.
I installed the battery back in the car; the car started fine. Resting voltage is 12.85VDC, running voltage (idle) is 14.10VDC. Looks fine to me.
The car is new enough, I didn't find any corrosion on the battery terminals or other wiring (grounds, etc)
So... any thoughts on what's wrong with this car?