A script to set the bclm to allow full battery charge, report on the charging progress, then reset the bclm when charging stops.

readme.md

For limiting a MacBook battery's charge to prolong its life I find bclm a lot more straightforward than AlDente.

sudo bclm write 81 keeps the hardware battery percentage at 80% on both my MacBooks (I haven't found a reason to use persist, yet).

I would often set the bclm to 100 for a period of time to get a full charge before taking one to a coffee shop. With this script I don't have to remember to reset it.

I currently combine it with telling DropBox to quit (which seems to smooth out coffee shop wifi orientation) as well as connecting the VPN.

#!/bin/bash

wait_for() {
    func="$1"
    timeout_seconds=10
    elapsed_seconds=0
    while [ $elapsed_seconds -lt "$timeout_seconds" ]; do
        if "$func"; then
            return 0
        fi
        sleep 1
        elapsed_seconds=$((elapsed_seconds + 1))
    done
    return 1
}

vpn_is_connected() {
    mullvad status | grep "Connected" >/dev/null
}

tell() {
    local some_app="$1"
    local what="$2"

    is_running() {
        pgrep -x "$1" >/dev/null
    }

    case "$what" in
    quit)
        is_running "$some_app" || return 0
        ;;
    activate)
        ! is_running "$some_app" || return 0
        ;;
    esac

    echo "telling $some_app to $what.."
    osascript -e "tell application \"$some_app\" to $what" || return 1
}

tell "Dropbox" "activate" || exit 1

echo "starting full charge cycle.."
bclm-cc || exit 1

tell "Docker Desktop" "quit" || exit 1
tell "Dropbox" "quit" || exit 1

if ! vpn_is_connected; then
    # tell "Mullvad VPN" "activate"
    echo "telling mullvad to connect.."
    mullvad connect || exit 1
fi

echo "checking vpn connection.."
if wait_for "vpn_is_connected"; then
    echo "vpn connected; undock!, undock!"
else
    echo "vpn failed to connect" >&2
    exit 1
fi

Thanks to a tip from this very informative gist, I now have passwordless sudo set up.

sudo visudo

..opens /etc/sudoers in vim. I added this to the bottom:

[my username] ALL=(ALL) NOPASSWD: /usr/local/bin/bclm

Now sudo bclm no longer requires a password.

bclm-cc.sh

#!/bin/sh

has_battery() {
    pmset -g batt | grep -q 'InternalBattery'
}

is_not_plugged() {
    pmset -g batt | grep -q 'Battery Power'
}

is_plugged_and_not_charging() {
    pmset -g batt | grep -q 'AC Power' && pmset -g batt | grep -Eq 'charged|finishing|not charging'
}

is_plugged_and_charging() {
    pmset -g batt | grep -q 'AC Power' && pmset -g batt | grep -q 'charging' && ! pmset -g batt | grep -q 'not charging'
}

get_bat_pct() {
    current_capacity=$(ioreg -l | grep -o '"CurrentCapacity" = [0-9]*' | awk '{print $3}')
    max_capacity=$(ioreg -l | grep -o '"MaxCapacity" = [0-9]*' | awk '{print $3}')
    percentage=$(echo "($current_capacity * 100) / $max_capacity" | bc)

    echo "$percentage"
}

get_bat_status() {
    if is_not_plugged; then
        echo "discharging at $(get_bat_pct)%"
    elif is_plugged_and_not_charging; then
        echo "not charging at $(get_bat_pct)%"
    elif is_plugged_and_charging; then
        echo "charging at $(get_bat_pct)%"
    else
        echo "unknown"
    fi
}

reset_bclm() {
    if [ -z "$starting_bclm" ]; then
        return 1
    fi
    sudo bclm write "$starting_bclm"
}

wait_for() {
    func="$1"
    timeout_seconds=10
    elapsed_seconds=0
    while [ $elapsed_seconds -lt "$timeout_seconds" ]; do
        if "$func"; then
            return 0
        fi
        sleep 1
        elapsed_seconds=$((elapsed_seconds + 1))
    done
    return 1
}

reset_bclm_and_report() {
    reset_bclm && echo "bclm reset to $starting_bclm"
    echo "battery $(get_bat_status)"
}

handle_interrupt() {
    printf '\ninterrupted..\n'
    reset_bclm
    echo "bclm reset to $starting_bclm, waiting for effect.."
    wait_for "is_plugged_and_not_charging"
    echo "battery $(get_bat_status)"
    exit 0
}

if ! type bclm >//dev/null 2>&1; then
    echo 'bclm command not found, exiting' >&2
    exit 1
fi

if ! has_battery; then
    echo 'no battery found, exiting' >&2
    exit 1
fi

if is_not_plugged; then
    echo 'not plugged in, exiting' >&2
    exit 1
fi

starting_bclm=$(bclm read)
echo "current bclm is $starting_bclm"

if [ "$starting_bclm" -eq 100 ]; then
    echo 'nothing to do, exiting'
    exit 0
fi

trap handle_interrupt INT TERM

sudo bclm write 100
echo "bclm set to 100, waiting for effect.."
if ! wait_for "is_plugged_and_charging"; then
    echo "charging did not start"
    reset_bclm_and_report
    exit 0
fi

while is_plugged_and_charging; do
    printf "\rbattery charging at %s.." "$(get_bat_pct)%"
    sleep 5
done
echo

if is_not_plugged; then
    echo 'battery unplugged..' >&2
    reset_bclm_and_report
    exit 1
fi

echo "charging is stopped"
reset_bclm_and_report