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ckamps avatar image
ckamps asked

How to minimize power consumption of Venus OS + Raspberry Pi 4 B?

What are the ways in which I can reduce power consumption of a Raspberry Pi 4 2 GB running Venus OS 2.73?

I recently installed my system in an off-grid location. It uses a POE HAT and POE for power and Ethernet for network connectivity. The system has a single VE.direct cable connected to a SmartSolar 100/20 charge controller.

I’m looking for ways to disable unused features so that I can minimize power consumed by the device.

The Raspberry Pi currently appears to be consuming more than 6 watts. (I’ll update this post with a more precise number shortly).

Since Bluetooth, WiFi, and HDMI are not needed on this system, they seem to be obvious candidates to completely disable.

I’ve consulted several resources for reducing power consumption:

  • https://blues.io/blog/tips-tricks-optimizing-raspberry-pi-power/
  • https://learn.pi-supply.com/make/how-to-save-power-on-your-raspberry-pi/

Ideas I’ve explored for minimizing power consumed:

  • Disabling Bluetooth
  • Disabling WiFi
  • Disabling HDMI
  • Disabling LEDs
  • Adjusting the cpufreq setting

Any other ideas?

For the ideas listed above, I’ve attempted the following approaches. However, it’s not clear to me which of these approaches are compatible with Venus OS. Any feedback on your experience with these or similar techniques would be helpful.

I understand that some of the techniques listed below might not persist after an upgrade of Venus OS. I’m OK with having to script and reapply some changes after an OS upgrade.

Disabling Bluetooth

I’ve unchecked “Enabled” under Bluetooth in the console, but it’s not clear to me whether or not this action results in Bluetooth being completely disabled at the OS level).

I’ve also tried:

# update-rc.d -f bluetooth remove

And:

# rfkill block bluetooth

Disabling WiFi

I’ve attempted several approaches including:

# connmanctl
> disable wifi`

And:

# rfkill block wifi

Disabling HDMI

This approach doesn’t appear to apply to Venus OS: https://learn.pi-supply.com/make/how-to-save-power-on-your-raspberry-pi/#turn-off-hdmi

Disabling LEDs

This is a conventional approach on Raspbian OS, but it’s not clear that it’s supported on Venus OS:

# cat /boot/config.txt
# Disable LEDs
dtparam=act_led_trigger=none
dtparam=act_led_activelow=off
dtparam=pwr_led_trigger=none
dtparam=pwr_led_activelow=off

Adjusting the cpufreq setting

Per https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#using-dvfs, I attempted the following changes. However, it’s not clear to me that this technique is supported on Venus OS.

# cat /boot/config.txt
# Allow undervoltage
dvfs=1

Combined with:

# cpufreq-set -g powersave
Venus OSRaspberry Pi
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1 Answer
johnny-brusevold avatar image
johnny-brusevold answered ·

@ckamps

This works on my rpi4 8GB v1.4 and Venus OS 2.73

Download overlay files from here

https://github.com/raspberrypi/firmware/tree/master/boot/overlays

act_led.dtbo

disable-wifi.dtbo


in /u-boot/config.txt


[pi4]
dtparam=act_led


# Disable the PWR LED
dtparam=pwr_led_trigger=none
dtparam=pwr_led_activelow=off


# Disable the Activity LED
dtparam=act_led_trigger=none
dtparam=act_led_activelow=off


# Disable ethernet port LEDs
dtparam=eth_led0=4
dtparam=eth_led1=4


# Disable wifi
dtoverlay=disable-wifi


# Set cpu speed and volt
arm_freq=400
over_voltage=-2


Turn off BT did not work with overlay file in rpi4

Maybe 'hciconfig hci0 down' from terminal turns it off ?

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johnny-brusevold avatar image johnny-brusevold commented ·

Here is some additional information

PI 4 pulls with the above config.txt

440mA at 5.00V = 2.2W

with

hciconfig hci0 down

and

rfkill block bluetooth

Is the consumption 410mA at 5.00V = 2.1W

even after a reboot in demo mode

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ckamps avatar image ckamps johnny-brusevold commented ·

Thanks! After applying many of these settings, I was able to measure the Raspberry Pi running Venus OS at 2W and 0.2A.

I have also moved away from using the PoE+ HAT and instead am using a 12V DC to USB C converter to power the Raspberry Pi via the USB port. The PoE+ HAT seemed to be unnecessary in my solution.

FWIW, here’s the power consumption breakdown in my off-grid camera system:

Device Amps Watts
TP-Link CPE710 WiFi Extender / Passive PoE Injector 0.2A 2W
Raspberry Pi w/Venus OS 0.2A 2W
Gigabit PoE Switch (w/no loads) 0.1A 1W
PoE Camera 1 (IR off) 0.3A 4W
PoE Camera 2 (IR off) 0.3A 4W

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