that happens when you buy a $9 multimetar from e-bay...

anyways I tried different multimeter and it was showing that when car idles on 750 rpm the voltage is dropping down constantly...
before i started the engine the voltage was 11.55
after 3-4 minutes of idling the multimeter was showing 10.7 v (engine on)
after I switched the engine off the battery started recovering slowly.

I couldn't start the engine again because the there was not enough power so I conected it to the charger

So what do you guys think:
is it a short somewhere that is draining the battery when the engine is on
or is it the alternator not charging the battery?
thanks...

__________________
-------------------------------------
1988 mercedes 190e 2.3 AT 160k miles