Can anyone recommend some settings for my Sunsynk aux port.

I have an additional grid tie inverter on this port.

Im in the UK and want to export the aux port when the battery is full, the manual is clear as mud

mine is currently set to 100 / 80

There aren't many parameters. My interpretation is as follows:

Micro Inverter Zero Export - Micro Inverter will be switched off if the system starts to export to the utility.

AC Couple Frequency High - When not coupled to the 50Hz grid (off grid), the inverter will increase frequency to this value to signal to the Micro Inverter to cut back.

AC Couple Off Battery: Battery State of Charge when high frequency operation kicks in.

AC Couple On Battery: Battery State of Charge below which 50Hz operation resumes.