Turning off battery while on AC

[Ian Smith]

On Fri, 28 Sep 2012 13:01:02 -0700, nm.knife at gmail.com wrote:

 > Sorry if this has been answered, but is there a way to set a laptop (I have
 > ThinkPad X220) not to draw energy from the battery when it's on AC? In
 > Windows once the battery is not charging and you are on AC, the battery is
 > totally bypassed. You can imagine this being better than it constantly
 > charging and being used.
 > 
 > Is this something that is hardware built in, or is it controlled by the OS?
 > Is there an equivalent in FreeBSD? (or maybe GNU/Linux)?

What indicates that it's using energy from the battery while on AC?  
Please show:
 % acpiconf -i0
when the battery is fully charged and running on AC power?

Earlier Thinkpads (I have a couple of T23s) always fully charge the 
battery then disconnect it, letting it slowly self-discharge until the 
reported capacity drops to ~95%, over some days usually, when it gets 
boosted back to 100%  IBM were careful not to trickle-charge Li-Ion 
batteries, avoiding risk of fire or explosion - Lenovo too, I guess. 

If yours is not behaving like that, then acpiconf -i0 should show 
something happening on 'Present rate', which shows charge rate during 
charging, and discharge rate while running from battery.  When fully 
charged (State: high) running on AC, it should show 0mW (on some, mA):

smithi on t23% acpiconf -i0
Design capacity:        43200 mWh
Last full capacity:     31850 mWh
Technology:             secondary (rechargeable)
Design voltage:         10800 mV
Capacity (warn):        2160 mWh
Capacity (low):         432 mWh
Low/warn granularity:   1 mWh
Warn/full granularity:  1 mWh
Model number:           IBM-02K7026
Serial number:            932
Type:                   LION
OEM info:               Panasonic
State:                  high
Remaining capacity:     100%
Remaining time:         unknown
Present rate:           0 mW
Present voltage:        12381 mV

 > Lyubomir Grigorov (bgalakazam)

cheers, Ian