2000 C280, 103m.

Battery 4 yrs old @ 68m. Voltage regulator replaced 1.5 years ago @ 90m.

Last 2 mornings car would not start. Car starts and runs fine with jump. Battery before no start is 10.8-11.5v. Seems to be charging fine at 14v+ with car running. After driving ~20 miles, battery is at 12.45v.

It is a AutoZone battery and they have checked it twice now and they say battery is good so I must have some parasitic drain overnight.

What are the common places to check?

The only thing odd recently was after pulling into garage, wife says a few wisps of smoke or steam came out of left front hood area. I've checked and nothing seems amiss. Car ran fine after that but a few days later the battery drain started.
__________________
glenmore
1999, 2000 C280
2000 C230K