Dead car

Shut my car off last night.About 3 hours later went to start it and Nothing!

No lights, no horn, no clicking starter, and couldn’t remove the key from the ignition.

Today went back to the car, checked ECM fuse, Good.

Checked batt. Dead!

Jumped battery, Lights came on, car started.

Took it to the Auto shop where they cheked the Batt, 620CCA. Alternator putting out 15amps.

I would really like to know what the problem was.

DagoBert

If the alternator is putting out 15 amps, that is a serious concern. Most of them put out around 95 amps. Surely, this is a mistake???

Other than that, I would check the basics. Clean and tighten the battery terminals. Check for excessive corrosion on the cables. Check chassis grounds for tightness and security. If the battery is more than four or five years old, consider replacing it anyway. Make sure you didn’t do something silly, like leave on headlights, map lights, glove box door open, etc. If all checks good, you may have a parasitic draw somewhere.

15 volts? Check cables at terminals for corosion. Should not be green and deteriorated. Check terminals. I have seen were all looked good and you can take a pocket knife and stick it across the batt terminal and post and it would crank. If there is corrosion between term and post it is not going to charge or crank and it will get hot at term. It can be tight and look good and still be bad. Otherwise you could have a large drain. and something stayed on. I have seen a volvo with worn door switches run a battery down in 10 hrs because it was windy and caused the door to move making body control module stay on. After alarm was set and kept going off it was figured out. Good luck