http://www.ahfung.com/car/_image/CLK01.jpg

what's the difference between this place and MBWorld.org??

anyway... i really need some help.
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Whenever I leave the car idle for 4 successive days, the battery dies and I cant even open the door (need to use the mechanic key)

I tried 2 fully-charged batteries and the result is just the same. It happened 3 times so far.....

I think it's not related to the alternator by logic because

(1) if I dont leave it idle for 4 successive days, no problems at all. I'd been driving the car for more than one month until the first time it could not start after being idle for 4 days.
It implies the alternator is charging the battery.

(2) if the alternator fails, the warning light should turn on.
I tried to disconnect the alternator and the warning light did turn on.

(3) i checked the voltage of the battery during engine run, it read 13.8V so I think the alternator is working.

(4) the battery was fully charged before I installed it.

(5) If everything goes off including the boot-lamp, the amp-meter reads 300mA for the battery.

Someone told me in the technical menu, the std currect should be 50mA.

But I still got a big question.

Even if it's 300ma, the battery has 100A in total. Well assume it's half-full and has only 50A

it should still last 50 / 0.3 = 166 hours or 7 days.

but it just dies in 4 days....

of course, I will get it a service check by MB but any clues?