Battery level for contact sensor
I use the following config:

{
          "accType" : "thermostat",
          "ain" : "099950409035",
          "battery" : true,
          "name" : "Heizung Leana",
          "temperature" : true,
          "window" : false
        },
        {
          "accType" : "window",
          "ain" : "099950409035",
          "battery" : true,
          "name" : "Fenstererkennung KiZi"
        },

Same AIN but battery is reported correct as Thermostat but not as window.

Battery level is also wrong on HAN-FUN optical window contact:

{
          "accType" : "contact",
          "ain" : "119340208370",
          "battery" : true,
          "name" : "Kleines Fenster KiZi"
        },


In both cases the battery is reported as empty but shown as 90 or 100% in web interface of fritz box.