Private Declare Function GetSystemPowerStatus Lib "kernel32" _
(lpSystemPowerStatus As SYSTEM_POWER_STATUS) As Long

Private Type SYSTEM_POWER_STATUS
    ACLineStatus As Byte
    BatteryFlag As Byte         ' Batteriezustand
    BatteryLifePercent As Byte  ' Prozentuale Angabe des Reststromes
    Reserved1 As Byte
    BatteryLifeTime As Long     ' Verbleibende Akku-Laufzeit
    BatteryFullLifeTime As Long ' Durchschnittliche Dauer eines Akkuzyklus
End Type

Private Sub Form Timer()
 
    GetSystemPowerStatus SysPower
 
    '.... Prüfroutine Akku o. Netz
 
    With SysPower
        Select Case .ACLineStatus
            Case 0: Me!EnergyStatus = "Akkubetrieb"
            Case 1: Me!EnergyStatus = "Netzbetrieb"
            Case 2: Me!EnergyStatus = "Unbekannt"
        Case Else: End Select
    End With
 
End Sub