Normal batteries voltage during cranking
 

My car is a 96 E320, but I guess the answer to my question applies pretty well to any model:

It is normal for batteries voltage to drop momentarily during cranking due to the significant load. Just wondering what is considered "normal" during this brief period, for healthy batteries?

How much of a drop are you seeing? Voltage should remain fairly steady (+-1V), although the AMPS used during that cycle increase dramatically.

High current draw drops voltage, and the usual minimum cranking voltage spec is 10.5v for a 12v battery, which should actually measure about 12.6 open circuit, no load, at room temperature when fully charged.

Duke

The higher the current draw, the lower the voltage will go. Also, the lower the temperature, the lower the voltage will go. There is no set answer without taking load, state of charge, and temperature into consideration.