NAME
acpibat —
ACPI Battery
SYNOPSIS
acpibat* at acpi?
DESCRIPTION
Theacpibat 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
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.