Date: Tue, 6 Nov 2012 09:10:00 GMT From: J B <jb.1234abcd@gmail.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/173414: ACPI battery time incorrect Message-ID: <201211060910.qA69A06s003211@freefall.freebsd.org>
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The following reply was made to PR kern/173414; it has been noted by GNATS. From: J B <jb.1234abcd@gmail.com> To: bug-followup@FreeBSD.org, jb.1234abcd@gmail.com Cc: Subject: Re: kern/173414: ACPI battery time incorrect Date: Tue, 6 Nov 2012 10:07:47 +0100 $ sysctl -d hw.acpi.battery.time hw.acpi.battery.time: remaining time in minutes Why is it impossible or improper to compute and show battery's remaining time ? Because the machine is on on-line power supply ? The battery's state, that is, its remaining time, is still valid and of interest to user at any machine state (load, etc), regardless of power supply being on-line or off-line. I want to know WHAT IF, at any time (without or with consideration of current machine state (load, etc) in the computation of battery remaining time), I disconnected the on-line power supply, could I expect to happen to my machine with regard to expected length-of-time availability of battery power supply. If you think that the battery's "percent capacity remaining" is enough, then you are mistaken. hw.acpi.battery.life: percent capacity remaining The battery's "percent capacity remaining" is misleading because its max level is degrading over time (the 100% of a new battery is not the same 100% after a year or so of random discharging and charging). They just do not tell me how much estimated run time I would have as I explained above. This is what Linux shows about my battery state: $ cat /proc/acpi/battery/BAT0/info present: yes design capacity: 56160 mWh last full capacity: 38720 mWh battery technology: rechargeable design voltage: 10800 mV design capacity warning: 1936 mWh design capacity low: 200 mWh capacity granularity 1: 1 mWh capacity granularity 2: 1 mWh model number: COMPATIBLE serial number: 2413 battery type: LION OEM info: BATSZ $ cat /proc/acpi/battery/BAT0/state present: yes capacity state: ok charging state: charged present rate: 0 mW remaining capacity: 38720 mWh present voltage: 12405 mV These are the original and degraded capacity values of 100% I am talking about: ... design capacity: 56160 mWh last full capacity: 38720 mWh ... remaining capacity: 38720 mWh ... So, please compute this hw.acpi.battery.time: remaining time in minutes and make it available at any time, and at any state of the machine. There is a good use for this data.
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