Venus + Raspberry + automated safe shutdown options (perhaps PiJuice)?

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belsy003 asked Jul 6, '22

Venus + Raspberry + automated safe shutdown options (perhaps PiJuice)?

Hi everyone,

I've been researching but doesn't appear that anyone has already asked/answered this, so apologies if this is a double-up. I'm new to the forum, Victron, raspberry and linux, so I'm learning my way :)

I'm wishing to have a safe shutdown option for a Venus Pi (preferably a 3b+) as it will be inaccessible and also likely experience power loss overnight during the winter months (off-grid DC setup, huge battery and solar but also a power hungry system).

I don't want to take the chance of just pulling the power, because any corruption of the micro SD card will be a huge pain to remedy. It would need to be a fully automated process (all of the Raspberry shutdown procedures I've seen need to be manually triggered) - and also having UPS functionality would be an added bonus.

The PiJuice HAT seems to be the most intuitive hardware option, however it appears that the 'soft shutdown' function only works through scripts on a Raspbian OS, and so doesn't appear to be compatible with the Venus OS.

It would seem to me that my options are -

1. Find someone who has PiJuice or similar properly working on a Venus OS, who can provide advice for activating automated safe shutdown

2. Find an old Venus package for Raspbian, and PiJuice should work out of the box (anyone have a link?)

3. An alternative software / hardware / UPS option which offers safe shutdown functionality (any suggestions?)

4. Get a Cerbo instead? (assuming they won't be affected by sudden power loss)

Has anyone come across this situation before and provide any advice please? I'm not looking to reinvent the wheel, I can reasonably follow other people's coding but have zero coding experience of my own.

Venus OS Raspberry Pi ups

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Answer 1 · 2022-07-07T01:41:27Z

johanndo answered · Jul 07, 2022 at 01:41 AM

No sudden power loss if you have a battery to monitor (what you have btw.) this is better than any UPS solution. Just wire its power supply next to the battery.

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belsy003 commented · Jul 07, 2022 at 09:06 PM

Thanks for your thoughts, however I expect the battery to reach maximum safe discharge, hence the need for safe shutdown (more important than a UPS, which would just be a nice benefit on top)

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johanndo belsy003 commented · Jul 07, 2022 at 10:56 PM

A safe shutdown doesnt mean it uses no more power, just a thought.

It is not meant to handle bms disconnects. However, it would be easy to shutdown the Pi / Venus by a script based on a voltage reading, SOC or any other parameter / alarm from the dbus to chicken out before the battery disconnects - but then you loose remote control. You just use python to call halt or shutdown -h now

you can do it easily by using this in your dbus callback function:

import subprocess

...

subprocess.run('shutdown -h now')

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Answer 2 · 2022-07-07T12:35:31Z

gainestr answered · Jul 07, 2022 at 12:35 PM

https://off-grid-garage.com/victron-venus-os-shutdown-feature/

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belsy003 commented · Jul 07, 2022 at 09:08 PM

I've seen this video before, however rewatching gave me the idea of using a relay to detect power loss and trigger the jumpers, rather than a push button / switch. Theoretically it seems like a viable (albeit a bit cumbersome) option. Worth prototyping. Thankyou :)

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Answer 3 · 2022-07-07T20:07:12Z

jeroen answered · Jul 07, 2022 at 08:07 PM

For 2: http://updates.victronenergy.com/feeds/venus/candidate/packages/raspbian-buster/

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belsy003 commented · Jul 07, 2022 at 09:07 PM

Brilliant, that definitely seems like a viable option

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jeroen ♦ belsy003 commented · Jul 07, 2022 at 09:17 PM

For completeness, that is not supported by Victron Energy. It is literally "AS IS", no promises that is doing anything useful or that someone will make it do something useful if it doesn't.

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Answer 4 · 2022-07-29T22:40:03Z

pvpax answered · Jul 29, 2022 at 10:40 PM

You have huge PV, battery and hungry consumers. By the time the load gets cut off, the battery should quickly recover from "unhealthy" voltage and should easily be able deliver a few watts for the raspi. At least for some hours until PV production starts again.

I have enough faith in my battery to keep the venus running via a DC-DC converter connected directly to the battery, bypassing the BMS.

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Answer 5 · 2022-07-30T00:27:30Z

Kevin Windrem answered · Jul 30, 2022 at 12:27 AM

As mentioned in a previous post, look at ShutdownMonitor:

https://github.com/kwindrem/ShutdownMonitor

In combination with:

https://github.com/kwindrem/RpiGpioSetup

These will give you a menu-based shutdown and also a way to trigger shutdown by grounding a GPIO pin. This, you can connect to a low voltage cut-off relay.

I have yet to have a single SD card corruption by just powering down my Pi 4. If there is corruption, it is repaired on the next boot by the OS and I never see it.

Another approach is to make a copy of the system SD card and carry it with you in case there are problems.

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johanndo commented · Jul 30, 2022 at 07:20 PM

Hi Kevin,

Would be great to have a backup menu on the Venus to mirror the current installation on a bootable SD card in a usb sd card reader.

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