I only perused the original post quickly, so I may have missed something.

You cannot confirm a battery drain by measuring voltage. You need to connect an ammeter in series with one of the battery cables, turn everything off and see how much current is being drawn. On a 123 car it should not be more than a few milli volts.

Milli-amps ?
Steve

Sorry I sort of dropped this thread. I was in Japan. There's quite a few Mercedes over there. No old ones, though. Pretty much no old cars at all.

Now for the battery discharge: I have found the major problem in my analysis of my battery discharge was a faulty multimeter. Yes, cheap multimeters are cheap for a reason! I suspected as much when it blew the fuse everytime despite being within range.

So, with my new multimeter, I have found that the drain oscillates between 2 and 9 milliamps (if I'm reading that correctly). Which as I understand it from previous posts is just what it should be! My conclusion is that the first time my battery discharged was just from sitting too long without running or charging. The second time must have been a light left on or something else. I'm going to leave the #2 fuse in and see if it discharges again, which it shouldn't.

Thank you everybody for your help, and I have definitely learned a bit about electricity. I see now why measuring voltage will not tell me enough about a battery discharge.

Happy driving!

__________________
marshall

1982 300TD (220,000 mi.)