Advanced Configuration and Power Interface Specification

Power Source and Power Meter Devices
10.2.2.6 _BST (Battery Status)
This object returns the present battery status. Whenever the Battery State value changes, the system
will generate an SCI to notify the OS.
Arguments:
None
Return Value:
A Package containing the battery status as described below
Return Value Information:
_BST returns a package in the format below
Package {
Battery State
Battery Present Rate
Battery Remaining Capacity
Battery Present Voltage
}
// Integer (DWORD)
// Integer (DWORD)
// Integer (DWORD)
// Integer (DWORD)
Table 10-276 BST Return Package Values
Element Format Description
Battery
State
Battery
Present
Rate
Battery
Remaining
Capacity
Battery
Present
Voltage
Integer
(DWORD)
Integer
(DWORD)
Integer
(DWORD)
Integer
(DWORD)
Bit values. Notice that the Charging bit and the Discharging bit are mutually
exclusive and must not both be set at the same time. Even in critical state,
hardware should report the corresponding charging/discharging state.
• Bit [0] – 1 indicates the battery is discharging.
• Bit [1] – 1 indicates the battery is charging.
• Bit [2 ]– 1 indicates the battery is in the critical energy state (see
Section 3.9.4, “Low Battery Levels”). This does not mean battery failure.
Returns the power or current being supplied or accepted through the battery’s
terminals (direction depends on the Battery State value). The Battery Present
Rate value is expressed as power [mWh] or current [mAh] depending on the
Power Unit value.
Batteries that are rechargeable and are in the discharging state are required to
return a valid Battery Present Rate value.
• 0x00000000 – 0x7FFFFFFF in [mW] or [mA]
0xFFFFFFFF – Unknown rate
Returns the estimated remaining battery capacity. The Battery Remaining
Capacity value is expressed as power [mWh] or current [mAh] depending on the
Power Unit value.
Batteries that are rechargeable are required to return a valid Battery Remaining
Capacity value.
• 0x00000000 – 0x7FFFFFFF in [mWh] or [mAh]
• 0xFFFFFFFF – Unknown capacity
Returns the voltage across the battery’s terminals.
Batteries that are rechargeable must report Battery Present Voltage.
• 0x000000000 – 0x7FFFFFFF in [mV]
• 0xFFFFFFFF – Unknown voltage
Note: Only a primary battery can report unknown voltage.
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