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My RPi 4 consumes about 0.5A after executing sudo halt, while according to this post it should draw at least an order of magnitude less (0.069A). The green LED blinks several times then goes off, but the device seems to stay powered indefinitely. Notably, the 3.3V pins on the GPIO remain powered, and the LED on the network interface keeps blinking.

This happens of a vanilla Raspbian Buster image with all upgrades installed. The RPi is powered via the USB-C connector. Additionally, it's connected to Ethernet, there's an HDMI screen attached to it, as well as a wireless USB keyboard / mouse. Disconnecting those cables doesn't change the power consumption significantly.

The only hardware modification present on the board is a reset button connected to GLOBAL_EN signal and ground on the J2. Essentially, when the button is not pressed, the board connectivity is not modified in any way. When the GLOBAL_EN signal is grounded, the current drops to 0.15A.

Dmitry Grigoryev
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2 Answers2

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This has been a source of confusion for some time. About 4 months before you posted your question a "Raspberry Pi Engineer" claimed in this forum post that power consumption would be 3mA (15mW power) following a poweroff command. We're still waiting for this :)

To be fair, there has been some improvement in power consumption since that post, but as of today, with the current "critical" version of the bootloader (Apr 29 2021), it remains an order of magnitude greater than what was claimed more than two years ago. It also requires changing two of the bootloader's parameters from their default values: WAKE_ON_GPIO must be set to 0, and POWER_OFF_ON_HALT must be set to 1.

A couple of "side effects" of this Low Power Mode to be aware of are:

  • The handy "Single Button Start/Stop" feature - enabled with the gpio-shutdown dtoverlay - will no longer work as GLOBAL_EN is required for a re-start.

  • The 3V3 bus is disabled; GLOBAL_EN is pulled up to 5V, and it must be brought LOW, then released, to effect the restart/reboot.

Further on the subject of "low power", there are more effective ways to reduce power consumption:

  1. A "Zero Power" solution employing a RTC is described here.

  2. One of many "X-Low Power" solutions from @bablokb's GitHub site cleverly employs a simple flip-flop to power down an external voltage regulator. Also includes KiCAD files if you want to have a PCB made (very neat, very German :)

Seamus
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The Pi4 SHOULD enter a low power state on Halt, but this prevents the power up by pulling pin 5 low.

There is a patch to make it operate the same as earlier models which continue to use power when shutdown. If using this the RUN pin should be used to restart.

The original Buster image works, apparently the Foundation changed later images.

My Pi4 (early 2GB model) running Raspbian Raspberry Pi reference 2019-06-20 vcgencmd bootloader_config shows:-

BOOT_UART=0
WAKE_ON_GPIO=0

I haven't measured current but on poweroff the 3.3V power is off.

Milliways
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