Hi guys, this is now SOLVED. For anyone else with a similar experience, I have found that even though there was correct power to the alternator, fully functioning alternator/ belts and inadequate voltage coming back from the alternator output doesn't neccessarily mean the alternator is at fault. The charging system is wider than this and also includes the starter motor. Having found this out and removing the protective undertray to the engine I found a cable broken away from the starter motor which obviously plays a part in obtaining the correct output from the alternator. A simple new connector and refit to the starter motor cured the problem immediately. Hope this helps someone else out there.
Thank you so much for this post!
You saved me a lot of money and frustration!
I had the same problem as you; 4 volts at the alternator and battery light at the the dashboard.
I will provide some images so the next person with this problem can get some more help:
Checked the cable at the starter and it was indeed broken.
Picked up a new cable shoe (is that the english word for it?) at a local gass station. Costet next to nothing, like 50 cent.
Reused the cable and cleaned up the connection.
Started the car and it works!
Charging battery at 14.X volt and no battery light.
Did the job outside in the Norwegian arctic winter. No stress, this is a job any (semi) handy person can do. I spent around two, maybe three hours, including the trip to the gas station and reassembly of battery, plastic protection.