1. Acer WMI Battery interface driver (acer-wmi-battery)

1.1. Introduction

Some Acer laptops support setting battery charge control limits and allow a user to calibrate their battery.

1.2. WMI interface description

The WMI interface description can be decoded from the embedded binary MOF (bmof) data using the bmfdec utility:

[WMI, Dynamic, Provider("WmiProv"), Locale("MS\\0x409"), Description("Class used to control smart battery, Version 2.88"), guid("{79772EC5-04B1-4bfd-843C-61E7F77B6CC9}")]
class BatteryControl {
  [key, read] string InstanceName;
  [read] boolean Active;

  [WmiMethodId(19), Implemented, read, write, Description("Get battery Information Interface.")] void GetBattInfoInterface([in] uint32 uBatteryInfoIndex, [in] uint32 uBatteryNo, [out] uint32 uReturn);
  [WmiMethodId(20), Implemented, read, write, Description("Get Battery Health Control Status.")] void GetBatteryHealthControlStatus([in] uint8 uBatteryNo, [in] uint8 uFunctionQuery, [in] uint8 uReserved[2], [out] uint8 uFunctionList, [out] uint8 uReturn[2], [out] uint8 uFunctionStatus[5]);
  [WmiMethodId(21), Implemented, read, write, Description("Set Battery Health Control.")] void SetBatteryHealthControl([in] uint8 uBatteryNo, [in] uint8 uFunctionMask, [in] uint8 uFunctionStatus, [in] uint8 uReservedIn[5], [out] uint16 uReturn, [out] uint16 uReservedOut);
  [WmiMethodId(22), Implemented, read, write, Description("Get Battery Function Data.")] void GetBatteryFunctionData([in] uint8 uFunctionMask, [in] uint8 uReservedIn[3], [out] uint8 uReturnCode[2], [out] uint8 uBACStartTime[2], [out] uint8 uBACStopTime[2], [out] uint8 uBACStatus, [out] uint8 uReservedOut[9]);
  [WmiMethodId(23), Implemented, read, write, Description("Set Battery Function Data.")] void SetBatteryFunctionData([in] uint8 uFunctionMask, [in] uint8 uBACSwitch, [in] uint8 uReservedIn[6], [out] uint16 uReturnCode, [out] uint8 uReservedOut[2]);
};

For all methods the uBatteryNo is always 0x1, there are no known Acer laptop models with two batteries.

1.2.1. WMI method GetBatteryInfoInterface()

Returns additional battery information, the data seems to be based on the “Smart Battery Data Specification”. The only known value for uBatteryInfoIndex is 0x8, the battery temperature.

1.2.2. WMI method GetBatteryHealthControlStatus()

This interface does not exist on all Acer laptops, it returns whether battery charge limiting or calibration mode is enabled.

When calling this method, uFunctionList is a bitmask with known values:

Value	Description
0x01	Health mode supported
0x02	Calibration mode supported

uFunctionStatus is a 5 byte array known elements are 0 for health mode and 1 for calibration mode. A non-zero value means the mode is enabled.

1.2.3. WMI method SetBatteryHealthControl()

This interface does not exist on all Acer laptops, it enables battery charge limiting or battery calibration.

The argument uFunctionMask is known to accept either 0x01 for setting health mode or 0x02 for calibration mode; other values are unknown. uFunctionStatus is an uint8 value, a non-zero value enables the given mode.