Welcome to the EMO Community Forums, @Elettric . . . I have moved your new topic to this thread for discussion on the EMO battery.
At three years old, it is very possible that the battery could be degrading.
Otherwise, changing the charging cable and/or the power plug to the cable might bring his charge time back up as these can go bad over time.
If this does not help and since he is off warranty, you can contract service@living.ai for advice. They might be able to direct you to a repair person in your area or if you would be able to change the battery yourself, they will help with advice and the battery itself. You may want to read this thread.
My best to you.