the terminology is from the BMW service manuals, not from me... lol... the tests i am talking about are inside the cluster, you unlock your cluster and get to the voltage test (there are engine temp, fuel in liters, engine speed in RPMs, velocity in kmh, etc, etc..) one of the tests, is voltage, you should see it when car is not running and then, when it is running, to see the alternator output...

There are 21 tests, test #2 is always unlocked, tests the needles of the cluster, the 19 is the lock/unlock test, you use your VINs last 5 digits, say it is LV12345, you add 1+2+3+4+5=15, then you use 15 as unlock key, it unlocks all the other tests...

it is better if you do a search for these hidden cluster tests - i am running off my memory, and might be wrong in some minute detail...

also, do a search for the battery, we had a few very recent posts within last couple of weeks about how to test the battery and what voltage is condered OK and at which level to dump the battery...