Quasi-sleep script for the CM4 (qsleep.sh)
With no real suspend on the CM4, grandrew's script fakes it: busy processes throttled to 1–2 % CPU, backlight off, powersave governor — about 13 h on a charge.
What it takes
- Software only
- Config change
Difficulty 1 of 3 — easy.
Details
qsleep.sh finds processes using more than 2 % CPU with pidstat, clamps them with cpulimit, switches the backlight off through /sys/class/backlight and hooks into the power button by replacing lxde-pi-shutdown-helper; pressing the button again undoes it. The second revision adds the powersave governor, turns the DSI output off with wlr-randr after 60 s, re-scans for busy processes every minute and restores the previous brightness. Dependencies are just sysstat and cpulimit; it was written against Raspberry Pi OS Bookworm with labwc.
grandrew reports around 13 h from a smartphone-like usage pattern, and Rex measured roughly 4 % battery drain per hour while asleep. Known limits: the GPU cannot be fully powered down and the keyboard cannot be locked without firmware changes. paragonnov's uConsole-Sleep packages the same idea as a service.
Links
Open at Forum threadRelated mods
paragonnov's Debian package remaps the power key to a real screen-off sleep: backlight and LCD off, keyboard unpowered, CPU pinned to its minimum clock.
Michael_Wolf's Lua monitor for clock, power draw, temperature and battery, plus the benchmark showing the backlight is what actually drains a uConsole.
hotellonely's Python script logs the PMIC's voltage and current every 0.1 s until the console dies, giving a real watt-hour figure for any cell or pack.
On the original CM4 image the kernel left the charger at 300 mA while running; a one-line udev rule sets constant_charge_current to 2.4 A.
Any genuine branded 3,000–3,500 mAh 18650 works, flat-top or button-top; listings claiming much more than 3,500 mAh are fakes.
The 21700 version of HG's NVMe battery board fits the stock backplate and roughly doubles runtime: 4 h 31 min of 1080p playback against 2 h 27 min on 18650s.