I have the 20071223, which I have used several times. I hooked up a Volvo battery that was not working, and the charger lights indicated "fully charged" (green) after a few seconds. Placed the battery back in the car, some interior lights went on but no engine click or turnover. It's not the car, I put in a different battery and the car started right up. Meanwhile, I put the first battery back on the charger, still shows as fully charged. Any ideas?