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    SubjectRe: [PATCH 00/10] Add RT5033 charger device driver
    Hi!

    > Some comments on the end-of-charge behavior. The rt5033 chip offers three
    > options. In the Android driver, a forth option was implemented.

    Hmm. I'm working on that on motorola-cpcap driver, and I guess this is going
    to be common problem for many drivers.

    > - By default, the rt5033 chip charges indefinitely. The current goes down but
    > there is always a charge voltage to the battery, which might not be too good
    > for the battery lifetime.
    > - There is the possibility to enable a fast charge timer. The timer can be
    > set to 4, 6, 8... 16 hours. After that time has elapsed, charging stops
    > and the battery gets discharged. This option with a timer of 4 hours was
    > chosen by Beomho Seo in the patchset of March 2015. However, that option
    > is confusing to the user. It doesn't initiate a re-charge cycle. So when
    > keeping plugged in the device over night, I find it discharging on the
    > next morning.
    > - The third option of the rt5033 chip is enabling charging termination. This
    > also enables a re-charge cycle. When the charging current sinks below the
    > end-of-charge current, the chip stops charging. The sysfs state changes to
    > "not charging". When the voltage gets 0.1 V below the end-of-charge constant
    > voltage, re-charging starts. Then again, when charging current sinks below
    > the end-of-charge current, the chip stops charging. And so on, going up and
    > down in re-charge cycles. In case the power consumption is high (e.g. tuning
    > on the display of the mobile device), the current goes into an equilibrium.
    > The downside of this charging termination option: When reaching the end-of-
    > charge current, the capacity might not have reached 100 % yet. The capacity
    > to reach probably depends on power consumption and battery wear. On my mobile
    > device, capacity reaches 98 %, drops to 96 % until re-charging kicks in,
    > climbs to 98 %, drops to 96 %, and so on. Not reaching 100 % is a bit
    > confusing to the user, too.

    Is the system powered from the battery in the not-charging case?

    Anyway, we should teach userspace that "full battery" does not neccessary mean 100%,
    as keeping battery at 4.3V wears it down quickly.

    Best regards,
    Pavel
    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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