ACPIBAT(4) | Device Drivers Manual | ACPIBAT(4) |
acpibat
— ACPI
Battery
acpibat* at acpi?
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.
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.
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.
March 17, 2010 | NetBSD 10.99 |