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ACPIBAT(4) NetBSD Kernel Interfaces Manual ACPIBAT(4)
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acpibat -- ACPI Battery
acpibat* at acpi?
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
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
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.
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.
acpi(4), envsys(4), envstat(8), powerd(8)
The acpibat driver appeared in NetBSD 1.6.
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 9.1 March 17, 2010 NetBSD 9.1