It's not unknown for VW (and others) to have issues with their computer programing, my wife's 2015 Fabia was part of a Recall for "something to do with the battery" (often a convenient excuse to cover a mistake made by someone).

The newer the car the more electrical / electronic / computer "aids", "assists" and consumer "comforts" are on the cars so the more for the battery and charging system to cater for so comparing cars now only a few years different is getting less and less relevant.

Your car could have a problem but if you like the VCDS figures then battery charges of 86% and 92% and 12.5v and 12.6v look good, at point of time at least.

There seems to be a bit of a sea change in the charging pattern since I charged to 86% SOC and most certainly since last Saturday when I took the last VCDS scan at 78% SOC, its charging now (all short runs as per normal) more or less continuously at 14.4/14.8V and hasn't fallen below 12.8/13.1V at any time, will keep a eye on the DVD for a few more days before next scan.

19:14:28 26/04/2026

IDE00019 Voltage terminal 30 12.2 V

MAS16744-IDE01836 12-volt battery-Battery current -7.064 A

MAS16744-IDE01837 12-volt battery-Temperature of battery sensor 34 °C

MAS16744-IDE01839 12-volt battery-Battery charge status 78 %

MAS16744-IDE01841 12-volt battery-Battery internal resistance 7.2 mOhm

MAS16744-IDE01842 12-volt battery-Usable battery charge 31 Ah

MAS16744-MAS22232 12-volt battery-Battery aging: charge-related 96 %

MAS16744-MAS22233 12-volt battery-Battery aging: performance-related 91 %

MAS16745-IDE01843 Quiescent current management-Battery voltage at rest 12.5 V

Edited 29 April29 Apr by Johngerard

Why not try charging the battery to 100% then disconnect the battery monitoring connector on the battery negative (doing away with s/s) and run like that for a while and see what you get. The car won't blow up, battery disintegrate or world end by trying this despite what some think or feel. Give the battery and alternator a bit of an easier time, who knows the holiday might help the battery monitor s/s to return to its normal programmed demands. Who knows the secrets of the VW and their contractors programming, left hand, right hand, upsets with changes of contracts and back again.

I can't charge to 100% with my present charger, it trickle charges at 1 to 2A, then when the voltage reaches 14.4V it reduces to a measured 0.17A at a ~ 13.2V which I doubt very much would achievce "100%" SOC even after days on end charging.

I'm quite happy now, so far, that once the engine is running then the battery isn't supplying any of the electrical load and that the BMS system will hopefully maintain between 75% ish and 85% SOC depending on trip times etc.

Edited 29 April29 Apr by Johngerard

9 minutes ago, Johngerard said:

I'm quite happy now

Well that's about as good as it's going to get. 🙂

Just so you know and/or as an experiment I'd still suggest you charge the battery as much as you can then disconnect the battery monitoring s/s and let the alternator do its work unrestricted/unhindered for a while but not if this will take you away from quite happy.