function Test-IsOnBattery {
    Param([string]$computer)

    $isPowerOnLine = [BOOL](Get-WmiObject -Class BatteryStatus -Namespace root\wmi -ComputerName $computer).PowerOnLine

    if ($isPowerOnLine -eq $true) {
        return [String]"Power on line"
        # return $false
    } else {
        return [String]"On Battery"
        # return $true
    }
}




Test-IsOnBattery -computer $computer

Информация о батарее в WMI

C:\> Get-WmiObject -Class Win32_Battery


__GENUS                     : 2
__CLASS                     : Win32_Battery
__SUPERCLASS                : CIM_Battery
__DYNASTY                   : CIM_ManagedSystemElement
__RELPATH                   : Win32_Battery.DeviceID="0001NotebookBAT"
__PROPERTY_COUNT            : 33
__DERIVATION                : {CIM_Battery, CIM_LogicalDevice, CIM_LogicalElement, CIM_ManagedSystemElement}
__SERVER                    : DESKTOP-GL0U977
__NAMESPACE                 : root\cimv2
__PATH                      : \\DESKTOP-GL0U977\root\cimv2:Win32_Battery.DeviceID="0001NotebookBAT"
Availability                : 2
BatteryRechargeTime         :
BatteryStatus               : 2
Caption                     : Внутренняя батарея
Chemistry                   : 6
ConfigManagerErrorCode      :
ConfigManagerUserConfig     :
CreationClassName           : Win32_Battery
Description                 : Внутренняя батарея
DesignCapacity              :
DesignVoltage               : 12364
DeviceID                    : 0001NotebookBAT
ErrorCleared                :
ErrorDescription            :
EstimatedChargeRemaining    : 100
EstimatedRunTime            : 71582788
ExpectedBatteryLife         :
ExpectedLife                :
FullChargeCapacity          :
InstallDate                 :
LastErrorCode               :
MaxRechargeTime             :
Name                        : BAT
PNPDeviceID                 :
PowerManagementCapabilities : {1}
PowerManagementSupported    : False
SmartBatteryVersion         :
Status                      : OK
StatusInfo                  :
SystemCreationClassName     : Win32_ComputerSystem
SystemName                  : DESKTOP-GL0U977
TimeOnBattery               :
TimeToFullCharge            :
PSComputerName              : DESKTOP-GL0U977

C:\> Get-WmiObject -Class batterystatus -Namespace root\wmi


__GENUS            : 2
__CLASS            : BatteryStatus
__SUPERCLASS       : MSBatteryClass
__DYNASTY          : CIM_StatisticalInformation
__RELPATH          : BatteryStatus.InstanceName="ACPI\\PNP0C0A\\0_0"
__PROPERTY_COUNT   : 20
__DERIVATION       : {MSBatteryClass, Win32_PerfRawData, Win32_Perf, CIM_StatisticalInformation}
__SERVER           : DESKTOP-GL0U977
__NAMESPACE        : root\wmi
__PATH             : \\DESKTOP-GL0U977\root\wmi:BatteryStatus.InstanceName="ACPI\\PNP0C0A\\0_0"
Active             : True
Caption            :
ChargeRate         : 0
Charging           : False
Critical           : False
Description        :
DischargeRate      : 0
Discharging        : False
Frequency_Object   :
Frequency_PerfTime :
Frequency_Sys100NS :
InstanceName       : ACPI\PNP0C0A\0_0
Name               :
PowerOnline        : True
RemainingCapacity  : 35932
Tag                : 31
Timestamp_Object   :
Timestamp_PerfTime :
Timestamp_Sys100NS :
Voltage            : 12357
PSComputerName     : DESKTOP-GL0U977

Ссылки