Power management

An odio node powers off like any Debian headless box: via the Power API, via Home Assistant, or from the command line. For most setups, that’s enough. This page collects patterns for readers who want something more integrated, a single physical switch, or a fully-off state with no standby draw.

Is a sudden power cut safe?

Probably yes on recent Raspberry Pi OS images, for two reasons specific to odio:

Swap is disabled on the odio image install, removing one of the classic corruption paths on sudden power loss.
Logging is minimal on Raspberry Pi OS Trixie, journald has almost nothing to write, which means very little is in flight at any moment.

That doesn’t license cutting power at random every day, but a one-off brownout should usually leave the SD card intact.

Clean shutdown from software

Trigger a proper shutdown before cutting power:

From the embedded web UI, the odio application, or Home Assistant — use the Power controls.
From the API directly, POST /power/power_off (see Power API).
From SSH, poweroff or systemctl poweroff, either works. The odio installer deploys a polkit rule so the odio user can reboot and power off without sudo.

Once the node is fully off, it is safe to cut the physical power.

Single-switch setups (exploratory)

Some setups want one physical switch for both the Pi and the amplifier (kitchen-radio style). The switch has to translate to a clean software shutdown first, then cut the power, transparently.

Two directions are discussed on odios#46. Neither is fully validated. Feedback very welcome.

Smart plug with power monitoring (Home Assistant)

Use a ZigBee or Zwave smart plug that reports live current consumption:

Trigger a software shutdown via odio-ha or the Power API.
A Home Assistant automation watches the plug’s current reading.
When current drops to roughly zero (Pi fully off), the automation switches the plug off.
To power back on, turn the plug on from Home Assistant.

Status: tested on a Pi B+ with a Sonoff ZigBee plug, did not work. The B+ draws too little current to be reliably distinguished from zero, and boot time is long enough to defeat the ergonomics. Expected to work on ARM64 Pis (3B+, 4, 5, Zero 2 W) with higher idle current and faster boot, but not yet confirmed. If you try this on an ARM64 board, please share results on odios#46.

Hardware: relay plus GPIO

Proposed by @pbattino in the same discussion. A small relay module with a timer delay, where the physical switch triggers both:

A delayed power cut to the Pi and the amplifier (the delay on the relay must cover the full shutdown time).
A GPIO signal sensed by the Pi, which runs systemctl poweroff as the odio user. This triggers the same clean logind shutdown as the API and the UI, via the polkit rule mentioned above, no sudo needed.

Trade-offs: one extra hardware component (around €10 reported), GPIO wiring, and a small script to react to the input. In exchange, a fully off state with no standby draw.

Status: discussed, not tested. Contributions welcome, particularly from the electronics-savvy corner of the community, a wiring diagram, part list, and the reactive GPIO script would turn this into a concrete recipe.

Is it worth it at all?

Concrete numbers are documented on odios#35 for a Raspberry Pi B+ setup:

Idle draw: 1-3W.
At €0.25/kWh: roughly €2-7/year.
Carbon: up to ~1.5 kg CO2/year on the French grid (57 gCO2/kWh).

The same post explains the author runs his node continuously, reasoning that booting a Pi B+ is slow and stresses the SD card more than sitting idle. His original R&D SD lasted six years without failure under that regime.

Another point, from @pbattino on odios#46: a ZigBee smart plug has its own idle draw, so any savings from powering the Pi off may be eaten by the plug itself.

Open question for your own setup. If you’ve measured idle and standby numbers, please share them on the discussions.