困っていたこと

Macbook 12（Catalina）のバッテリー残量が、スリープしている間に、どんどん減って悲しい気持ちになります。。
というわけで、原因と対策を調べてみました。

原因

通電してる「スリープ」状態から、ほぼ電源オフの「スタンバイ」状態に変わるまでの時間が3時間かかることが原因の模様。

原因の詳細

2つのスリープ状態

MacOSのスリープ状態には、次の2つがあります。

緩やかに通電したままの「スリープ」モード
- メモリやUSBにも通電している
- バッテリー残量がそれなりに減る
通電を完全に切る「スタンバイ」モード
- メモリの状態はSSDに保存され、USBからの給電もストップする
- バッテリー残量がほとんど減らない
- 復帰時にSSDからメモリに読み込むため、数十秒ほどの待ち時間が発生する
- ディープスリープとも呼ばれたりする模様。
  - 言葉の定義についてはこちらの方が丁寧に書かれています。

「スリープ状態」から「スタンバイ」への移行タイミング

このスリープモードからスタンバイモードへの切り替わりタイミングですが、
デフォルトで、バッテリー残量が多いときは24時間後、少ないときで3時間後となります。
バッテリー残量が多いか少ないかのしきい値は50%です。

そのため、初期状態では、

バッテリーの残量が50%以上の場合はスリープ状態のままバッテリー残量が減っていく（24時間後なので、普通はなかなかスタンバイに切り替わらず）。
バッテリーの残量が50%以下の場合、3時間後にスタンバイモードに切り替わる。

という流れになります。

対策

pmsetコマンドで、バッテリー使用時の「スリープ」から、「スタンバイ」に切り替える時間を短くする。
私は、次のように変更してみました。

バッテリーの残量が80%以上の場合は20分後にスタンバイに切り替わる。
バッテリーの残量が80%未満あると判断された場合は10分後にスタンバイに切り替わる。

変更手順

1. 現在の設定の確認（pmset -g）

電源を抜いて、バッテリー状態にして実施します。
電源アダプタモードとバッテリーモードがあり、今回はバッテリーモードで確認します。
なお、コマンドで見にくい場合は、Appleメニューの「このMacについて」の「システムレポート」からもこの設定を確認することができます。

バッテリー稼働時のpmsetコマンド（デフォルト）

% pmset -g

System-wide power settings:
Currently in use:
 standbydelaylow      10800　←バッテリー少ない時「スタンバイ」への時間（デフォルトは3時間）
 standby              1
 halfdim              1
 hibernatefile        /var/vm/sleepimage
 gpuswitch            2
 powernap             0
 disksleep            10
 standbydelayhigh     86400　←バッテリー多い時「スタンバイ」への時間（デフォルトは24時間）
 sleep                1 (sleep prevented by coreaudiod, sharingd)
 autopoweroffdelay    28800
 hibernatemode        3
 autopoweroff         1
 ttyskeepawake        1
 displaysleep         2
 tcpkeepalive         1
 highstandbythreshold 50　←highとlowのしきい値（デフォルトは50%）
 acwake               0
 lidwake              1

下記の設定が確認できます。

standbydelaylow
- バッテリー残量が少ない時の「スタンバイ」へ移行するまでの待ち時間
- 10800(3時間)
standbydelayhigh
- バッテリー残量が多い時の「スタンバイ」へ移行するまでの待ち時間
- 86400(24時間)
highstandbythreshold
- パッテリー残量の多いor少ないを切り替えるしきい値
- 50%

2. 設定を変更するコマンド（pmset -b）

実際に待ち時間を変更するpmsetコマンドを叩きます。

pmsetコマンドでスタンバイ時間への移行を短く

# バッテリーで動作している時のみ、スタンバイにするまでの時間を短く変更
sudo pmset -b standbydelayhigh 1200 standbydelaylow 600
#  バッテリー残量が多い時(standbydelayhigh)、1200秒(20分)に設定
#  バッテリー残量が少ない時(standbydelaylow)は、600秒(10分)に設定

#しきい値（standbydelayhighかstandbydelaylow）を残量80%に設定
sudo pmset -b highstandbythreshold 80

pmsetコマンドは、設定したい項目名と値をセットにして指定することができます。
-bオプションは、バッテリー動作時のみの設定 (-aはすべて、-cは電源接続時)です。

3. 設定後の内容の確認（pmset -g）

値が反映されたか確認してみます。

バッテリー稼働時のpmsetコマンド（設定変更後）

% pmset -g

System-wide power settings:
Currently in use:
 standbydeylow        600　←600(10分)に変わった
 standby              1
 halfdim              1
 hibernatefile        /var/vm/sleepimage
 gpuswitch            2
 powernap             0
 disksleep            10
 standbydelayhigh     1200　←1200(20分)に変わった
 sleep                1 (sleep prevented by useractivityd, sharingd)
 autopoweroffdelay    28800
 hibernatemode        3
 autopoweroff         1
 ttyskeepawake        1
 displaysleep         2
 tcpkeepalive         1
 highstandbythreshold 80　←80％に変わった
 acwake               0
 lidwake              1

無事、値が反映されていることがわかります。
なお、Appleメニューの「このMacについて」の「システムレポート」からもこの設定を確認することができます。

AC電源接続時は、値が変わっていないことがわかります。

さいごに

いまのところ調子は良いですが、しばらくこれで様子を見てみようと思います。

参考

https://teineini.net/20190218-macbookair-denchi/
https://warexperimental.hatenablog.com/entry/2019/02/19/233340
https://qiita.com/usagimaru/items/70cc39d5b1b0368fe028

(おまけ) PMSETコマンドのマニュアル

「man pmset」コマンドの中身(2019/10/20現在)です。
マニュアルですので、ここが一番正確かと思います。


SYNOPSIS
     pmset [-a | -b | -c | -u] [setting value] [...]
     pmset -u [haltlevel percent] [haltafter minutes] [haltremain minutes]
     pmset -g [option]
     pmset schedule [cancel | cancelall] type date+time [owner]
     pmset repeat cancel
     pmset repeat type weekdays time
     pmset relative [wake | poweron] seconds
     pmset [touch | sleepnow | displaysleepnow | boot]

DESCRIPTION
     pmset manages power management settings such as idle sleep timing, wake on administrative access, automatic restart on power loss, etc.

     Note that processes may dynamically override these power management settings by using I/O Kit power assertions.  Whenever processes override any system power settings, pmset
     will list those processes and their power assertions in -g and -g assertions. See caffeinate(8).

SETTING
     pmset can modify the values of any of the power management settings defined below. You may specify one or more setting & value pairs on the command-line invocation of pmset.
     The -a, -b, -c, -u flags determine whether the settings apply to battery ( -b ), charger (wall power) ( -c ), UPS ( -u ) or all ( -a ).

     Use a minutes argument of 0 to set the idle time to never for sleep disksleep and displaysleep

     pmset must be run as root in order to modify any settings.

SETTINGS
     displaysleep - display sleep timer; replaces 'dim' argument in 10.4 (value in minutes, or 0 to disable)
     disksleep - disk spindown timer; replaces 'spindown' argument in 10.4 (value in minutes, or 0 to disable)
     sleep - system sleep timer (value in minutes, or 0 to disable)
     womp - wake on ethernet magic packet (value = 0/1). Same as "Wake for network access" in the Energy Saver preferences.
     ring - wake on modem ring (value = 0/1)
     powernap - enable/disable Power Nap on supported machines (value = 0/1)
     proximitywake - On supported systems, this option controls system wake from sleep based on proximity of devices using same iCloud id. (value = 0/1)
     autorestart - automatic restart on power loss (value = 0/1)
     lidwake - wake the machine when the laptop lid (or clamshell) is opened (value = 0/1)
     acwake - wake the machine when power source (AC/battery) is changed (value = 0/1)
     lessbright - slightly turn down display brightness when switching to this power source (value = 0/1)
     halfdim - display sleep will use an intermediate half-brightness state between full brightness and fully off  (value = 0/1)
     sms - use Sudden Motion Sensor to park disk heads on sudden changes in G force (value = 0/1)
     hibernatemode - change hibernation mode. Please use caution. (value = integer)
     hibernatefile - change hibernation image file location. Image may only be located on the root volume. Please use caution. (value = path)
     ttyskeepawake - prevent idle system sleep when any tty (e.g. remote login session) is 'active'. A tty is 'inactive' only when its idle time exceeds the system sleep timer.
     (value = 0/1)
     networkoversleep - this setting affects how OS X networking presents shared network services during system sleep. This setting is not used by all platforms; changing its
     value is unsupported.
     destroyfvkeyonstandby - Destroy File Vault Key when going to standby mode. By default File vault keys are retained even when system goes to standby. If the keys are
     destroyed, user will be prompted to enter the password while coming out of standby mode.(value: 1 - Destroy, 0 - Retain)

GETTING
     -g (with no argument) will display the settings currently in use.
     -g live displays the settings currently in use.
     -g custom displays custom settings for all power sources.
     -g cap displays which power management features the machine supports.
     -g sched displays scheduled startup/wake and shutdown/sleep events.
     -g ups displays UPS emergency thresholds.
     -g ps / batt displays status of batteries and UPSs.
     -g pslog displays an ongoing log of power source (battery and UPS) state.
     -g rawlog displays an ongoing log of battery state as read directly from battery.
     -g therm shows thermal conditions that affect CPU speed. Not available on all platforms.
     -g thermlog shows a log of thermal notifications that affect CPU speed. Not available on all platforms.
     -g assertions displays a summary of power assertions. Assertions may prevent system sleep or display sleep. Available 10.6 and later.
     -g assertionslog shows a log of assertion creations and releases. Available 10.6 and later.
     -g sysload displays the "system load advisory" - a summary of system activity available from the IOGetSystemLoadAdvisory API. Available 10.6 and later.
     -g sysloadlog displays an ongoing log of lives changes to the system load advisory. Available 10.6 and later.
     -g ac / adapter will display details about an attached AC power adapter. Only supported for MacBook and MacBook Pro.
     -g log displays a history of sleeps, wakes, and other power management events. This log is for admin & debugging purposes.
     -g uuid displays the currently active sleep/wake UUID; used within OS X to correlate sleep/wake activity within one sleep cycle.  history
     -g uuidlog displays the currently active sleep/wake UUID, and prints a new UUID as they're set by the system.
     -g history is a debugging tool. Prints a timeline of system sleeplwake UUIDs, when enabled with boot-arg io=0x3000000.
     -g historydetailed Prints driver-level timings for a sleep/wake. Pass a UUID as an argument.
     -g powerstate [class names] Prints the current power states for I/O Kit drivers. Caller may provide one or more I/O Kit class names (separated by spaces) as an argument. If
     no classes are provided, it will print all drivers' power states.
     -g powerstatelog [-i interval] [class names] Periodically prints the power state residency times for some drivers. Caller may provide one or more I/O Kit class names (sepa-
     rated by spaces). If no classes are provided, it will log the IOPower plane's root registry entry. Caller may specify a polling interval, in seconds with -i <polling inter-
     val>; otherwise it defaults to 5 seconds.
     -g stats Prints the counts for number sleeps and wakes system has gone thru since boot.
     -g systemstate Prints the current power state of the system and available capabilites.
     -g everything Prints output from every argument under the GETTING header. This is useful for quickly collecting all the output that pmset provides. Available in 10.8.


SAFE SLEEP ARGUMENTS
     hibernatemode supports values of 0, 3, or 25. Whether or not a hibernation image gets written is also dependent on the values of standby and autopoweroff

     For example, on desktops that support standby a hibernation image will be written after the specified standbydelay time. To disable hibernation images completely, ensure
     hibernatemode standby and autopoweroff are all set to 0.

     hibernatemode = 0 by default on desktops. The system will not back memory up to persistent storage. The system must wake from the contents of memory; the system will lose
     context on power loss. This is, historically, plain old sleep.

     hibernatemode = 3 by default on portables. The system will store a copy of memory to persistent storage (the disk), and will power memory during sleep. The system will wake
     from memory, unless a power loss forces it to restore from hibernate image.

     hibernatemode = 25 is only settable via pmset. The system will store a copy of memory to persistent storage (the disk), and will remove power to memory. The system will
     restore from disk image. If you want "hibernation" - slower sleeps, slower wakes, and better battery life, you should use this setting.

     Please note that hibernatefile may only point to a file located on the root volume.

STANDBY ARGUMENTS
     standby causes kernel power management to automatically hibernate a machine after it has slept for a specified time period. This saves power while asleep. This setting
     defaults to ON for supported hardware. The setting standby will be visible in pmset -g if the feature is supported on this machine.

     standbydelayhigh and standbydelaylow specify the delay, in seconds, before writing the hibernation image to disk and powering off memory for Standby.  standbydelayhigh is
     used when the remaining battery capacity is above highstandbythreshold , and standbydelaylow is used when the remaining battery capacity is below highstandbythreshold.

     highstandbythreshold has a default value of 50 percent.

     autopoweroff is enabled by default on supported platforms as an implementation of Lot 6 to the European Energy-related Products Directive. After sleeping for <autopoweroffde-
     lay> seconds, the system will write a hibernation image and go into a lower power chipset sleep. Wakeups from this state will take longer than wakeups from regular sleep.

     autopoweroffdelay specifies the delay, in seconds, before entering autopoweroff mode.

UPS SPECIFIC ARGUMENTS
     UPS-specific arguments are only valid following the -u option. UPS settings also have an on/off value. Use a -1 argument instead of percent or minutes to turn any of these
     settings off. If multiple halt conditions are specified, the system will halt on the first condition that occurs in a low power situation.

     haltlevel - when draining UPS battery, battery level at which to trigger an emergency shutdown (value in %)
     haltafter - when draining UPS battery, trigger emergency shutdown after this long running on UPS power (value in minutes, or 0 to disable)
     haltremain - when draining UPS battery, trigger emergency shutdown when this much time remaining on UPS power is estimated (value in minutes, or 0 to disable)

     Note: None of these settings are observed on a system with support for an internal battery, such as a laptop. UPS emergency shutdown settings are for desktop and server only.

SCHEDULED EVENT ARGUMENTS
     pmset allows you to schedule system sleep, shutdown, wakeup and/or power on. "schedule" is for setting up one-time power events, and "repeat" is for setting up daily/weekly
     power on and power off events. Note that you may only have one pair of repeating events scheduled - a "power on" event and a "power off" event. For sleep cycling applica-
     tions, pmset can schedule a "relative" wakeup or poweron to occur in seconds from the end of system sleep/shutdown, but this event cannot be cancelled and is inherently
     imprecise.

     type - one of sleep, wake, poweron, shutdown, wakeorpoweron
     date/time - "MM/dd/yy HH:mm:ss" (in 24 hour format; must be in quotes)
     time - HH:mm:ss
     weekdays - a subset of MTWRFSU ("M" and "MTWRF" are valid strings)
     owner - a string describing the person or program who is scheduling this one-time power event (optional)

POWER SOURCE ARGUMENTS
     -g with a 'batt' or 'ps' argument will show the state of all attached power sources.

     -g with a 'pslog' or 'rawlog' argument is normally used for debugging, such as isolating a problem with an aging battery.

OTHER ARGUMENTS
     boot - tell the kernel that system boot is complete (normally LoginWindow does this). May be useful to Darwin users.
     touch - PM re-reads existing settings from disk.
     noidle - pmset prevents idle sleep by creating a PM assertion to prevent idle sleep(while running; hit ctrl-c to cancel). This argument is deprecated in favor of
     caffeinate(8). Please use caffeinate(8) instead.
     sleepnow - causes an immediate system sleep.
     restoredefaults - Restores Energy Saver settings to their default values. (Like clicking "Restore Defaults" in Energy Saver GUI).
     displaysleepnow - causes display to go to sleep immediately.
     resetdisplayambientparams - resets the ambient light parameters for certain Apple displays.
     dim - deprecated in 10.4 in favor of 'displaysleep'. 'dim' will continue to work.
     spindown - deprecated in 10.4 in favor of 'disksleep'. 'spindown' will continue to work.

EXAMPLES
     This command sets displaysleep to a 5 minute timer on battery power, leaving other settings on battery power and other power sources unperturbed.

     pmset -b displaysleep 5

     Sets displaysleep to 10, disksleep to 10, system sleep to 30, and turns on WakeOnMagicPacket for ALL power sources (AC, Battery, and UPS) as appropriate

     pmset -a displaysleep 10 disksleep 10 sleep 30 womp 1

     Restores the system's energy settings to their default values.

     For a system with an attached and supported UPS, this instructs the system to perform an emergency shutdown when UPS battery drains to below 40%.

     pmset -u haltlevel 40

     For a system with an attached and supported UPS, this instructs the system to perform an emergency shutdown when UPS battery drains to below 25%, or when the UPS estimates it
     has less than 30 minutes remaining runtime. The system shuts down as soon as either of these conditions is met.

     pmset -u haltlevel 25 haltremain 30

     For a system with an attached and supported UPS, this instructs the system to perform an emergency shutdown after 2 minutes of running on UPS battery power.

     pmset -u haltafter 2

     Schedules the system to automatically wake from sleep on July 4, 2016, at 8PM.

     pmset schedule wake "07/04/16 20:00:00"

     Schedules a repeating shutdown to occur each day, Tuesday through Saturday, at 11AM.

     pmset repeat shutdown TWRFS 11:00:00

     Schedules a repeating wake or power on event every tuesday at 12:00 noon, and a repeating sleep event every night at 8:00 PM.

     pmset repeat wakeorpoweron T 12:00:00 sleep MTWRFSU 20:00:00

     Prints the power management settings in use by the system.
     pmset -g

     Prints a snapshot of battery/power source state at the moment.

     pmset -g batt

     If your system suddenly sleeps on battery power with 20-50% of capacity remaining, leave this command running in a Terminal window. When you see the problem and later power
     and wake the computer, you'll be able to detect sudden discontinuities (like a jump from 30% to 0%) indicative of an aging battery.

     pmset -g pslog

SEE ALSO
     caffeinate(8)

FILES
     All changes made through pmset are saved in a persistent preferences file (per-system, not per-user) at
     /Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist

     Scheduled power on/off events are stored separately in /Library/Preferences/SystemConfiguration/com.apple.AutoWake.plist

     pmset modifies the same file that System Preferences Energy Saver modifies.