ACPIBAT(4)						   BSD 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 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 batter-
     ies.

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.

BSD
								  March 17, 2010							       BSD