Introducing signals for battery connection status

High Voltage Traction batteries can typically be disconnected from
the rest of the vehicle. Multiple connectors may exist and may
be handled independently. For example, during charging ground/minus
might be connected but not power/plus.

spec/Powertrain/Battery.vspec

@@ -8,9 +8,22 @@
 #
 
 #
-# Signals, attributes and actuators around the electric powertrain.
+# Signals and attributes related to the traction battery in vehicles with electrical powertrain.
+# For some vehicles the traction battery is referred to as the high voltage battery.
 #
 
+# It might be possible to disconnect the traction battery used by an electric powertrain.
+# This is achieved by connectors, typically one for plus and one for minus.
+PowerConnected:
+  datatype: boolean
+  type: sensor
+  description: Indicating if the power (positive terminator) of the traction battery is connected to the powertrain.
+
+GroundConnected:
+  datatype: boolean
+  type: sensor
+  description: Indicating if the ground (negative terminator) of the traction battery is connected to the powertrain.
+
 Temperature:
   datatype: float
   type: sensor
@@ -164,7 +177,6 @@ Charging.TimeToComplete:
   unit: s
   description: The time needed to complete the current charging process to the set charge limit. 0 if charging is complete, negative number if no charging process is active.
 
-
 Charging.Timer:
   type: branch
   description: Properties related to timing of battery charging sessions.