My laptop battery charged week ago up to 100% (fully).
Recently, I noticed (within this week) that it now charges only to 90%. First sign was that laptop battery led now always orange (charging) and never reach green (charged) when plugged. Charge without OS running never reaches green led too.
Linux (3.18) reports 90-93% charge when it reaches the level when it does not want to go up to 100% now.
Some more relevant information from kernel:
% cat /proc/acpi/battery/BAT0/state present: yes capacity state: ok charging state: charging present rate: 0 mA remaining capacity: 1611 mAh present voltage: 12038 mV % cat /proc/acpi/battery/BAT0/info present: yes design capacity: 2250 mAh last full capacity: 1759 mAh battery technology: rechargeable design voltage: 10800 mV design capacity warning: 176 mAh design capacity low: 18 mAh cycle count: 0 capacity granularity 1: 22 mAh capacity granularity 2: 22 mAh model number: X101CH serial number: battery type: LION OEM info: ASUS
I also remember that
/sys/class/power_supply/BAT0/voltage_now reported 12.6V (4.2V per cell) for 100% battery, but now it only reaches 12.04V (4.01V per cell).
/sys/class/power_supply/BAT0/current_now shows 0.
My battery design capacity is 2200mAh 10.8V 23Wh. My battery age is 2.5 years. Is this a sign of battery degradation? Do I need to worry about that?
EDIT: I remember before the "fall" last full capacity was about at 2050mAh and did not degrade much (by 300mAh at once or during 2-3 days) earlier. (I monitored it for a while with script)