• Mouse battery power status

    From AK@21:1/5 to All on Sun Jul 25 18:08:23 2021
    I use Linux, but am wondering if Windows has the same issue.

    My software shows my Logitech mouse battery as showing 55% for both a alkaline battery, a rechargeable LiMh, and another AA battery.

    Only the LiMh is fully charged of the batteries, so there is no way they are all 55%.

    Are others seeing something similar ?

    Curious.

    Thanks,
    Andy

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  • From Paul@21:1/5 to All on Sun Jul 25 23:08:32 2021
    AK wrote:
    I use Linux, but am wondering if Windows has the same issue.

    My software shows my Logitech mouse battery as showing 55% for both a alkaline battery, a rechargeable LiMh, and another AA battery.

    Only the LiMh is fully charged of the batteries, so there is no way they are all 55%.

    Are others seeing something similar ?

    Curious.

    Thanks,
    Andy

    Laptops use a coulomb counter. Because they in effect, measure "fuel",
    the percentage figure is relatively trustworthy.

    But other devices use a simple voltage measurement, then
    consult an open circuit voltage versus time table, to
    guess at how much of the battery is left. This is
    fraught with error.

    In your case, the Logitech does not know the cell chemistry.
    Consequently, it cannot "pop the correct table" into the
    math. It has probably assumed alkaline chemistry for all
    three readings, causing a fully charged LiMh to read
    lower than it should.

    The table is not linear. Most of the discharge curve,
    the battery may only change a little bit in voltage.
    Near the end of the discharge curve, there is a
    much larger change in voltage, so maybe it changes 0.5V
    between 5% charge and 4% charge. That's riding down the
    knee at the end. You could compute the inverse of the
    table used, then correct for the chemistry and apply
    a different table. But an even easier way, would be
    if the Logitech software stopped being so clever ("55%"),
    and the voltage measurement it's doing, was just
    printed on the screen instead ("1.354 volts"). Then, you
    could take the discharge curve yourself, and work out percent
    remaining.

    Paul

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From AK@21:1/5 to Paul on Mon Jul 26 06:50:33 2021
    On Sunday, July 25, 2021 at 10:08:36 PM UTC-5, Paul wrote:
    AK wrote:
    I use Linux, but am wondering if Windows has the same issue.

    My software shows my Logitech mouse battery as showing 55% for both a alkaline battery, a rechargeable LiMh, and another AA battery.

    Only the LiMh is fully charged of the batteries, so there is no way they are all 55%.

    Are others seeing something similar ?

    Curious.

    Thanks,
    Andy
    Laptops use a coulomb counter. Because they in effect, measure "fuel",
    the percentage figure is relatively trustworthy.

    But other devices use a simple voltage measurement, then
    consult an open circuit voltage versus time table, to
    guess at how much of the battery is left. This is
    fraught with error.

    In your case, the Logitech does not know the cell chemistry.
    Consequently, it cannot "pop the correct table" into the
    math. It has probably assumed alkaline chemistry for all
    three readings, causing a fully charged LiMh to read
    lower than it should.

    The table is not linear. Most of the discharge curve,
    the battery may only change a little bit in voltage.
    Near the end of the discharge curve, there is a
    much larger change in voltage, so maybe it changes 0.5V
    between 5% charge and 4% charge. That's riding down the
    knee at the end. You could compute the inverse of the
    table used, then correct for the chemistry and apply
    a different table. But an even easier way, would be
    if the Logitech software stopped being so clever ("55%"),
    and the voltage measurement it's doing, was just
    printed on the screen instead ("1.354 volts"). Then, you
    could take the discharge curve yourself, and work out percent
    remaining.

    Paul
    Thanks for the info.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)