Had a bit more light today after work so I tried turning the car on and watching the voltage. Car started at 12.6 volts. Reduced down to 12.0V and did not move for a good minute. After about three minutes the voltage got to about 13.7V.

I then unplugged the smart charge connector to see if it made a difference. I turned the car on and it remained at 12V before slowly creeping up.

When I removed the smart charger connector I noticed that the alternator was very hot. Considering the engine had only been on for a few minutes I think it has gone wrong.

Gonna order a new alternator and aux belt from euros as they have 30% off this weekend. Hopefully it will fix the problem.