Can anyone let me know whether the battery in the photo is a standard maintenance free or an AGM? Reason for the question is I am a little concerned that my alternator constantly runs at 14.9V output. I know that modern alternators are ECU controlled and I do very occasionally see lower outputs but 95% of the time it runs at 14.9V. I do a lot of sub 20 minutes runs but the battery is fully charged using a Ctek charger. Is this normal behaviour or is my battery being slowly cooked! I have a 2014 TD4 GS. Sorry photo didn't upload. The battery number is 6G9N-10655-RC It's a Varta 12v 80 Ah 700A (EN)

It would help if you could state which electrical loads are switched on at the time and the engine rpm. Another member of the failed FL2 clutch/DMF club, twice.

Only the LED daytime running lights and Air Con. Although I have turned the A/C off and it makes no difference. The 14.9 is there from tick over right through to full revs. It is very stable so the alternator appears to be working well, but the 14.9V just seems too high. I would have thought it should be 14.4 or 14.7V for AGM.

Air con may make no difference if the temperature you set is not low enough to switch on the condenser fans.
Try a resistive loads such as heated screens and see if you get a change. Another member of the failed FL2 clutch/DMF club, twice.