Hi Adrian, I've got Mondeo and similar alternator behaviour. After start voltage settles at around 13.7V (no load) then after switching lights, radio and fan goes down to 13.2V. During approx 45min trip from work it gradualy goes down to 12.7V (lights radio and heating fan on all the time. I'm not an expert but in my opinion at 12.7V battery is not being charged at all. I'm bit worried that at some point my car won't start. Did your battery ever went flat because of that?