Hi,

 

2005 Superb Elegance 1.8T engine.

Battery died, charged it overnight with a trickle charger.

After installing the battery, started the car and checked for charging voltage - 13.5V which dropped to 12.8 after several minutes.

checked voltage drop from battery negative to alternator casing - 0.1V.

checked voltage drop from battery positive to alternator stud - 1.2V - too high!

checked on the wires near the connections - the same results, so the problem is not the terminals.

 

How should i go further? any suggestions about where the problem lays?

 

Thanks!

The cable arrangement looks a little strange to me.  A 16mm-sq cable from battery positive to starter motor, then another, same size, going to alternator from there.  Try splitting your measurement into, batt + to starter, and starter to alternator B+ terminal, see which half is worse.  Cleaning the connections at the starter junction might be the key.

Looked on the diagram as well, but when i looked at the starter, it's not correlated - there is only one cable going there, and there is the same voltage drop.

 

I can only suggest replacing the cable from alternator to battery then.  May be a part number printed on it.