Image1 Raspberry Pi 5 Circuit Layout

Many makers know that the Raspberry Pi single-board computer gets stronger with each generation, meaning its computational performance improves, and it has more computing resources. However, despite being stronger, the price, size, and power consumption are still kept as compatible or controlled as possible.

In terms of price, Model B has maintained an official price below 35 dollars for a long time until the fourth generation when the price increased due to the increase in RAM capacity; in terms of size, Model B has always maintained a width of 85 x 56mm (based on Model B), but the height requirement has started to increase; power consumption is also kept as low as possible, but with performance improvements, it has still increased. The official power adapter for the fourth generation is about 15W while the fifth generation has reached 27W!

Note: It is important to remind that just because the adapter is rated at 15W or 27W does not mean that the Raspberry Pi will consume that much power; it indicates the maximum power it can provide. If the Raspberry Pi is connected to a keyboard, it will draw additional power from the adapter for the keyboard, and other peripherals like expansion cards, USB drives, and headphones will do the same.

How to reduce standby power consumption by 96%?

Even in standby mode, the fifth generation consumes quite a bit of power, about 1.29W (or some articles state between 1.2W and 1.6W ), and this 1.29W includes some power used for the LED indicator’s continuous blinking and keeping some power to wake up the main control chip from standby. If an expansion board (called HAT) is connected, even if the entire system enters standby mode, the power supply to the board’s 3.3V is stopped, but the 5V power supply through the USB interface will still continue, thus still consuming power.

So, how can we significantly reduce the standby power consumption of RPi 5? Some have thought of modifying the RPi 5 configuration file to achieve this. First, open and edit the configuration file with the command:

sudo rpi-eeprom-config –edit

(or just using -e is also fine)

This command opens and edits the EEPROM configuration data on the RPi 5 motherboard. Then, find a line in the file content:

POWER_OFF_ON_HALT=0

Change the last 0 to 1, save the file, and then restart. Upon reboot, it will read the EEPROM configuration data again, and at this point, standby power consumption can be significantly reduced. Tests shared online show a reduction from 1.2948W to 0.0498W (other articles have tested as low as 0.01W), saving over 96%.

Image2 Maker community figure Jeff Geerling’s test results can go as low as 0.01W

Setting Method for the Fourth Generation Raspberry Pi

Not only can the RPi 5 do this, but the already power-consuming RPi 4 can also achieve this by modifying the EEPROM configuration file, but the method is a bit more complex, as it also requires turning off the wake-up function of the GPIO pins. Similarly, first open and edit the file, change POWER_OFF_ON_HALT=0 to 1, and then modify another line:

WAKE_ON_GPIO=0 (this line is still visible in RPi 5, but it has no effect)

After modifying, save the file and restart, and you can achieve significant standby power savings, about 10mA. The benefit of saving power is that if there are some maker projects that are portable and powered by batteries, it can provide a longer standby time and usage time.

In addition to the above, there are other power-saving methods. Continuing with the RPi 4 as an example, you can also modify the configuration file in the operating system (SD card) located at /boot/config.txt to turn off all 4 LED indicators on the RPi 4, adding the following content to the configuration file:

# Turn off power LED indicators

dtparam=pwr_led_trigger=none

dtparam=pwr_led_activelow=off

# Turn off operation LED indicators

dtparam=act_led_trigger=none

dtparam=act_led_activelow=off

# Turn off Ethernet operation LED indicators

dtparam=eth_led0=4

# Turn off Ethernet connection LED indicators

dtparam=eth_led1=4

Turning off all 4 LED indicators can save about 2mA to 10mA of power, and the same method can be applied to RPi 3B+, but the numbers for the Ethernet indicators are slightly different; you need to change 4 to 14.

Alternatively, you can also limit the operating frequency of the main control chip in the /boot/config.txt file to restrict power consumption, for example, not exceeding 900MHz:

[all]

arm_freq=900

arm_freq_max=900

Other methods include using a headless setup which is possible when the Raspberry Pi is not using a keyboard, mouse, or screen, such as using the Raspberry Pi purely as a network server, as long as it can send and receive over the network, this can also save more power. Similar ideas can also be implemented by commands or configuration file edits to turn off wireless communication chips (Wi-Fi, Bluetooth), which can save about 40mA of current consumption.

Conclusion

Finally, returning to the fifth generation Raspberry Pi, even when using the above power-saving techniques, it will not affect the real-time clock (Real-Time Clock, RTC) system introduced for the first time in the fifth generation, and the watchdog timer (Watch Dog Timer, WDT) will also remain unaffected, all will function normally.

Perhaps in the future, there will be a competition to see who can make the Raspberry Pi last the longest in standby and operation. I remember a senior in my military service who was very thin; he said he was a driver in a solar car competition in college, and the competition was about how far the car could go with a person on board.

To win, one must consider various aspects such as solar panel efficiency, battery weight and capacity, motor efficiency, body strength, and weight, etc. People must also be as light as possible to help extend the range. Such challenges typically stimulate the development of various subsystem technologies and are not meaningless; optimizing software parameters is also one of the methods.

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