diff --git a/VectoCore/VectoCore/Configuration/Constants.cs b/VectoCore/VectoCore/Configuration/Constants.cs
index 69f96b0a9e11fbe881d57c14075c5fd8fae63491..85e0310e866b0bc10d1a99d2ffbf8c7247ab0862 100644
--- a/VectoCore/VectoCore/Configuration/Constants.cs
+++ b/VectoCore/VectoCore/Configuration/Constants.cs
@@ -51,8 +51,6 @@ namespace TUGraz.VectoCore.Configuration
 			public const string Prefix = "AUX_";
 			public const string PowerPrefix = "P_";
 
-			public const double FanElectricToMechanicalEfficiency = 1.05;
-
 			public static class IDs
 			{
 				public const string PTOTransmission = "PTO_TRANSM";
diff --git a/VectoCore/VectoCore/Models/SimulationComponent/Impl/EngineFanAuxiliary.cs b/VectoCore/VectoCore/Models/SimulationComponent/Impl/EngineFanAuxiliary.cs
index 2eb8804b7e1400be341206e59d56e170bc6b1c3a..246c7ebdd184f4aea89c7759f05dba5fe8a00e99 100644
--- a/VectoCore/VectoCore/Models/SimulationComponent/Impl/EngineFanAuxiliary.cs
+++ b/VectoCore/VectoCore/Models/SimulationComponent/Impl/EngineFanAuxiliary.cs
@@ -32,6 +32,7 @@
 using System;
 using TUGraz.VectoCommon.Utils;
 using TUGraz.VectoCore.Configuration;
+using TUGraz.VectoCore.Models.Declaration;
 using TUGraz.VectoCore.Models.SimulationComponent.Data;
 
 namespace TUGraz.VectoCore.Models.SimulationComponent.Impl
@@ -64,8 +65,8 @@ namespace TUGraz.VectoCore.Models.SimulationComponent.Impl
         }
 
         public Watt PowerDemand(Watt fanElectricalPower)
-        { 
-			return fanElectricalPower * Constants.Auxiliaries.FanElectricToMechanicalEfficiency;
+		{
+			return fanElectricalPower / DeclarationData.AlternatorEfficiency;
 		}
 
     }
diff --git a/VectoCore/VectoCoreTest/Models/SimulationComponent/EngineFanAuxTest.cs b/VectoCore/VectoCoreTest/Models/SimulationComponent/EngineFanAuxTest.cs
index 9549e124844f8fd0f503af1f48cc0950f7873a4b..b8f7eb9a371fca564c398dad4a6e91bdd42c7953 100644
--- a/VectoCore/VectoCoreTest/Models/SimulationComponent/EngineFanAuxTest.cs
+++ b/VectoCore/VectoCoreTest/Models/SimulationComponent/EngineFanAuxTest.cs
@@ -53,9 +53,9 @@ namespace TUGraz.VectoCore.Tests.Models.SimulationComponent
         }
 
         [
-        TestCase(14, 14.7),
-        TestCase(28, 29.4),
-        TestCase(7, 7.35)
+        TestCase(14, 20),
+        TestCase(28, 40),
+        TestCase(7, 10)
         ]
         public void TestEngineFanPowerDemandWithElectricalPower(double fanElectricalPower, double expectedPowerDemand)
         {