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Asked: 2015-06-11 17:28:16 +0800 CST

Battery indicator on MacbookAir 4,2 incorrect

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I have Ubuntu 15.04 installed. My computer and it's battery is a tad old (2011) and typically doesn't last longer than an hour.

The battery indicator % never seems representative of the actual status of the battery. It's never been at a 100%, even if the 'magsafe led' is green.

What can I do to debug this issue?

mac

1 Answers

  1. I have the same model of MacBook Air with Ubuntu 15.04 installed, and here's what I've found out so far. It looks like the battery driver is now reporting the capacity as the percentage of the design full capacity instead of the most recent full capacity. Cat the following files in the sysfs filesystem to see what I mean:

    /sys/class/power_supply/BAT0/capacity
    /sys/class/power_supply/BAT0/charge_now
    /sys/class/power_supply/BAT0/charge_full
    /sys/class/power_supply/BAT0/charge_full_design

    You'll see that "capacity" now equals "charge_now" / "charge_full_design" * 100 instead of "charge_now" / "charge_full" * 100.

    I installed the acpi tool with "sudo apt-get install acpi" to check what ACPI reports. "acpi -V" reports the correct percentage.

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