If you are on shore power the 13.6 you are seeing is the voltage coming from your converter/charger, not your actual battery voltage. And it is probably charging your batteries.
If you want to know your batteries state, you'll need a multimeter, and you'll need to disconect from shore power for a few hours to let the batteries stabilize. Then measure the voltage at the battery posts.
Mike
__________________
2015 27ft FC FB
WBCCI #3960
2019 F150 ecoboost
As mentioned, the 13.6V reading is what's coming off the charger. If you unplug from shore power, you should see that drop to 12.7 or so. And as advised, let batteries 'rest' a couple hours to get a true reading.
However...make sure your battery use/store switch is in "USE" position. If in 'store', they will not be charging.
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