uConStat statistics tool and CM4 power benchmark
Michael_Wolf's Lua monitor for clock, power draw, temperature and battery, plus the benchmark showing the backlight is what actually drains a uConsole.
What it takes
- Software only
Difficulty 1 of 3 — easy.
Details
uConStat.lua reads CPU frequency, power draw, temperature and battery percentage through a small uconsole.lua library; the MIT-licensed repo also has a benchmark script and a backlight helper. The useful part is the power/README: on a CM4 with 2 × 3,000 mAh cells, idle draw was 1.944 W with the backlight off and 4.133 W at level 9 — 11.4 h versus 5.4 h — while Wi-Fi and Bluetooth on or off made no measurable difference (1.944 vs 1.998 W). The 4G module adds 0.391 W at idle, about 1.8 h of runtime. Idle at 1200/1500/2100 MHz measured 1.894/1.944/2.242 W, and under load 1950 MHz gave the best performance per watt while staying under 45 °C.
The 2026 power-management thread adds the practical knobs for Rex's Trixie image: arm_freq and arm_freq_min in config.txt (not below 500 MHz at idle, which can break booting), btop for monitoring, and switching the AIO v2's SDR off, which hotellonely measured at about 0.8 W.
Links
Open at Forum thread- GitHubRepository
- GitHub — power benchmark READMERepository
- Forum: power-management tools discussion (2026)Forum
Related mods
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.
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.
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.