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 battery
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.