AGM battery compatibility with e53 alternator

[Blowout]

Replaced the acid flooded battery with an Champion AGM H7 in 2018 with 120k on the X5. According to records, dead battery occurred 3/2021. The car isn't drive much and thought that might have been the cause.

Radio stopped working sometime in 2022.

6/2022 battery dead but took a charge using a CTEK charger that has an AGM charging mode. Radio working again.

9/2023 battery dead, replaced with a Walmart Everstart Premium H7 AGM. Around 137k on odometer. I didn't record if radio worked.

3/2026 battery dead and CTEK charger died when trying to charge it. Over charged battery with an old 10 amp charger to a point where acid was discharged through the overflow. Replaced battery with a new Everstart H7 AGM. Radio worked again.

6/2026 battery dead but recharged fully with a new 5A AGM compatible charger. Radio works again.
.............................................

Radio has only worked occasionally over the past several years and could figure out whats wrong with it. Now I'm thinking it could be caused by the voltage being below a threshold. The car gets battery tendered every so often over the years because it becomes sluggish to start and tailgate unlock, dimmer interior lights and such have been noticed over the past several years.

After fully charging with a AGM charger the battery with the engine off all doors closed has been steady at 12.8V for 48 hours. The car wasn't run during that time. I don't think it has a parasitic drain anymore because the voltage has been steady.

Battery voltage with engine off - 12.8V
Voltage with engine started idling (headlights always on) - 13.8V
Engine 2000rpm- 14.0V

I'm thinking OEM alternator might not be compatible with charging an AGM battery. Anyone have thoughts or experienced something similar to this?

Not sure if I should change back to a flooded battery or change the alternator to a higher output model that would be AGM compatible.