2.0 DTI Charging problems

[Gophscfc]

Hi, I own a 2004 pre-facelift Vectra Estate. I'm having charging problems. The battery keeps going flat, after testing it with a multimeter the alternator was dead, brought and fitted a new one tested again and it was giving between 14-15 volts under load. A week later flat battery and again the alternator is not charging the battery. I used 2 multimeters one on the batter and one directly on the alternator to see if there was a drop between the two. The alternator reading was 0.7 volts? I have noticed that the second wire on the alternator (not the battery wire) looks like it has been replaced, does this wire turn on the alternators voltage regulators?

[CDTIauto]

Try a fresh battery, some alternators do not charge if the batteries iffy

[northpole]

And if that doesn't work if it was a refurbished one bring it back... worst-case it is the regulator that is gone ( it's a cheap part) but if you bought a new one it should be working.