acpibat(4) - NetBSD Manual Pages

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ACPIBAT(4)              NetBSD Kernel Interfaces Manual             ACPIBAT(4)


NAME

     acpibat -- ACPI Battery


SYNOPSIS

     acpibat* at acpi?


DESCRIPTION

     The acpibat driver supports ACPI batteries.

     The battery status is made available through the envsys(4) API.  The bat-
     tery information can be displayed also with the envstat(8) command:

       $ envstat -d acpibat0
                       Current  CritMax  WarnMax  WarnMin  CritMin Unit
              present:      ON
       design voltage:  14.400                                        V
              voltage:  16.267                                        V
           design cap:  74.880                                       Wh
        last full cap:  48.260                                       Wh
               charge:  47.910                      5.000%   0.414%  Wh (99.27%)
          charge rate:     N/A
       discharge rate:  16.641                                        W
             charging:     OFF
         charge state:  NORMAL

     Depending on the battery, the unit of measurement is either watt-hour
     (Wh) or ampere-hour (Ah) for the capacity related information.  From
     these the ``charge'' is usually the most interesting value, but it is
     possible to derive useful information also from the other values.  For
     example, when acpiacad(4) is disconnected, the ``discharge rate'' gives a
     coarse approximation of the current power consumption.  The ratio between
     the design capacity and the last full capacity on the other hand reveals
     the overall ``health'' of deteriorating lithium-ion batteries.


EVENTS

     The acpibat driver is able to send events to powerd(8) daemon when a
     capacity state has been changed.  The new state will be reported as the
     fourth argument to the /etc/powerd/scripts/sensor_battery script.  If a
     custom capacity limit was set via envstat(8), the acpibat driver will
     report a user-capacity event to the same script when current capacity
     limit has been reached.


SEE ALSO

     acpi(4), envsys(4), envstat(8), powerd(8)


HISTORY

     The acpibat driver appeared in NetBSD 1.6.


BUGS

     The ACPI specifications make a distinction between ``control method
     batteries'' and ``smart batteries''.  The acpibat driver only supports
     control method batteries.  Furthermore, acpibat does not yet support some
     additional battery information introduced in the ACPI 4.0 standard.

NetBSD 8.0                      March 17, 2010                      NetBSD 8.0