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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)

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7
  • 22% degradation in 2.5 years is maybe slightly unlucky, but not unreasonable. It does seem a little odd that after calibration it doesn't reach 100% of a lower value. I assume you've tried shutting down and plugging in overnight?
    – Chris H
    Commented Dec 3, 2015 at 9:12
  • I tried various ways: draining to 4% then charging fully, draining even to zero once, upcharging from 50-70%, did leave it for a 10hrs charging from 4%, tried "ladder": 30->50->30-60% (I need it to be portable for some time). But no, it stuck.
    – user529094
    Commented Dec 3, 2015 at 9:22
  • ... My machine is at least twice as old (I have directories last modified in 2011 that were created at installation). I have a similar amount of degradation to you but for a while my laptop wasn't seeing much use, just powered down and partially charged.
    – Chris H
    Commented Dec 3, 2015 at 9:24
  • Then I suggest a new battery is in order. I've bought third party battteries from reputable sources/brands in the past, with success., And by reputable I mean the actual seller, not the marketplace owner.
    – Chris H
    Commented Dec 3, 2015 at 9:25
  • I edited my question to include some more detail.
    – user529094
    Commented Dec 3, 2015 at 9:26

4 Answers 4

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This is a sign of battery degradation. If you look at the cat output, design capacity of your battery is 2250 mAh while the last full capacity is 1759 mAh. That's approximately a 21.8% degradation of battery life.You should perform a battery calibration to ensure that you have current and accurate information about battery wear.

Basic Calibration Instructions

Calibrating — or recalibrating, really, as the battery was calibrated in the past when the battery had more capacity — involves letting the battery run from 100% capacity straight down to almost dead, then charging it back to full. The battery’s power meter will then see how long the battery lasts and get a much more accurate idea of how much capacity the battery has left.

Source: howtogeek.com

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  • Yes I see that last full capacity dropped, however I attempted calibration ten times since I noticed that, both with and without OS running to no avail. I once flushed it down to 0% even laptop was not able to turn on then charged. Still stuck at 90%.
    – user529094
    Commented Dec 3, 2015 at 7:06
  • That's normal. It is unlikely that you will reach 100% again as your battery capacity has dropped by almost 22%. You should however, refrain from performing battery calibration very frequently and try not to drain your battery down to 10% or less as I recall reading something about that being harmful to your battery life.
    – Vinayak
    Commented Dec 3, 2015 at 7:11
  • Certain Lenovo computers have software that cuts off power to the battery at 60% charge and maintains that battery level (even with the notebook powered off), which apparently increases battery life. You could do this manually but I can only imagine what an inconvenience that'd be. I am unaware of any software programs that can achieve the same effect on other computers.
    – Vinayak
    Commented Dec 3, 2015 at 7:17
  • I understand that battery itself will not return back to 2200mAh 100%. Just confused with hardware indicator - will it consider new 1700mAh capacity as 100% and how to teach it.
    – user529094
    Commented Dec 3, 2015 at 7:20
  • Batteries age over time and a 22% drop in battery capacity for one that's been used over 2 years is not surprising. It's nothing that you need to worry about though. Not until battery wear guess up to 50% or more.
    – Vinayak
    Commented Dec 3, 2015 at 7:21
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As per the selected answer, this could be a sign of battery degradation.

Many laptops, however, (and as has been said in comments) have a mechanism that stops the battery from being charged to 100% to extend battery life. The options for these settings are often found in the laptop BIOS or an OEM specific software.

Check your BIOS or if there is a software (Asus have one called Power4Gear - https://www.asus.com/us/support/article/604/) that can configure your battery settings.

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3
  • No my BIOS there is very "dummy" - only permits setting USB settings, looking up processor and memory info, setting BIOS passwords and overriding boot options. Nothing more.
    – user529094
    Commented Dec 3, 2015 at 7:47
  • @siblynx, on other machines (as I mentioned in a comment under Vinayak's answer) this setting is accessed from a windows program. Whether there's a Linux approach is another matter. I don't know what feature of the motherboard is being addressed or how, so I don't know whether it could easily be addressed, or commands could be passed from a windowss virtual machine. I'm sure it will be a motherboard feature as the laptop can maintain a fixed charge level even when shut down.
    – Chris H
    Commented Dec 3, 2015 at 9:10
  • Ah, OK, sorry for misunderstanding.
    – user529094
    Commented Dec 3, 2015 at 9:13
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Everything got back to normal.

I continued to use same battery and now I use it. Last week, it got back to normal, suddenly. As it dropped to 90%, as now it recovered to 99-100% (sometimes it goes to 100%), I even did not noticed that again.

Battery voltage is normal 12,6V again nearly end of charge. Green led flashes again.

No healing programs however helped. It did recovered by itself.

Output of kernel:

% cat /proc/acpi/battery/BAT0/state                                            
present:                 yes
capacity state:          ok
charging state:          charging
present rate:            0 mA
remaining capacity:      1870 mAh
present voltage:         12440 mV
% cat /proc/acpi/battery/BAT0/info                                             
present:                 yes
design capacity:         2250 mAh
last full capacity:      1886 mAh
battery technology:      rechargeable
design voltage:          10800 mV
design capacity warning: 189 mAh
design capacity low:     19 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
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0

I've noticed that some newer laptops have a setting that when enabled, protects the battery from being overcharged.

When I enabled this setting on my laptop (Dell), Windows 10 battery charge doesn't go more than 90% (You can also have a much more detailed report running "powercfg /batteryreport" inside a command prompt)

Check your BIOS settings as this setting might be enabled. It is also possible that after an update, that Linux also protects the battery in some way. Though I can't confirm this with certainty.

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