how to Measure Raspberry Pi power consumption
There are many different statements and statements about the power consumption of Raspberry Pi. One or the other has actually measured the power consumption times. And now these values are haunting in forums and on blogs. Unfortunately, these measurements are of little help if it is not known how and what was measured accurately.
Both the measurement and the measurement result must then be viewed critically. Usually, such a result is worthless if nothing is known about the results of the measurement. To make things worse, each measurement results must always be interpreted correctly.
Measurement setup
To Measure Raspberry Pi power consumption Each measurement requires a defined measurement setup. This is the only way to ensure that a measurement returns the same values at a later date. Once the measurement setup has been documented, you can later retrace the measured values without having to repeat the measurement.
- Raspberry Pi Model A, A+, B (Rev. 2), B+, RPi 2 B, RPi Zero and for comparison an Odroid-C1
- Power adapter: USB power adapter with 5V / 2.1A
- SD card: Noname microSDHC / Class 10/8 GB
- Screen: HDMI monitor
- WiFi Adapter 1: Noname USB 2.0 Wireless / IEEE 802.11n / Chipset Ralink 5370
- WiFi Adapter 2: Noname USB 2.0 Wireless / IEEE 802.11n / Chipset Ralink 5372
- Keyboard: Hama Slim Line SL 640 (5V / 0.5A max.)
- Mouse: Noname Optical Wheel Mouse (5V / 50mA)
This measurement setup provides that the measurement is done behind the power supply that powers Raspberry Pi. The reason is that the power supply has a self-consumption, which depends on the power supply and current consumption and falsifies the measured values. Interesting is the pure power consumption of Raspberry Pi with possibly connected components.
To avoid a measurement error caused by different memory cards, a microSDHC card was used as the storage medium for all measurements. This is necessary because Raspberry Pi B+ does not accept standard SD cards. For this reason, the microSDHC card with an SD card adapter was used in the A and B models.
Meter: USB Power Meter from PortaPow
The meter is a PortaPow Premium USB + DC Power Monitor. This allows you to simultaneously measure voltage, current, and power at a USB port. For this purpose, the power monitor is looped into the power supply of Raspberry Pi. For this purpose, the Power Monitor has a USB-A plug and a USB-A socket. The meter has its own power supply and does not load the USB power adapter.
Data logging
In each case voltage, current and power were measured. The current was measured twice. Once during the boot process. The current value was continuously observed when fluctuating. The highest value was recorded (current peak).
The second measurement of the current took place after the boot process was completed, the login was displayed and Raspberry Pi was not used. So in the logged-out state and no additional active software or users. In this case, the meter showed the measured values without fluctuation.
The tension was usually between 5.11 and 5.16 V. The higher the current drain, the more the voltage is pressed. The value is not exciting unless you want to calculate the power.
The power is computationally a product of voltage and current. It will be displayed by the meter at the same time. Unfortunately mathematically not quite correct, which is certainly due to the tolerance. But that’s not so tragic in the second and third places after the decimal point. This inaccuracy is barely acceptable.
Measurement 1: Raspberry Pi naked
In this measurement, Raspberry Pi was operated completely without any other connected devices.
| Model | Tension | Electricity | Power | Current (peak) |
|---|---|---|---|---|
| RPi A | 5,157 v | 0,116 A | 0.603 W | 0.198 A |
| RPi A + | 5,160 v | 0.085 A | 0.438 W | 0.150 A |
| RPi Zero | 5,166 v | 0.084A | 0.433 W | 0.170 A |
| RPi B | 5,139 v | 0,341 A | 1,752 W | 0.422 A |
| RPi B + | 5,150 v | 0.203 A | 1,045 W | 0,264 A |
| RPi 2 B | 5,151 v | 0.199 A | 1.025 W | 0,345 A |
| ODROID-C1 | 5,152 v | 0.192 A | 0.989 W | 0.443 a |
In the ground state, the B+ model consumes about 140mA or 700mW less than the B model.
Raspberry P 2 B does not differ significantly from the B+ model. Most economical are the model Raspberry Pi Zero and A+.
Measurement 2: Raspberry Pi with Ethernet
In this measurement, Raspberry Pi was connected to the local network via Ethernet. This is referred to as the headless operation, in which ,Raspberry Pi is operated without a screen and keyboard. Over the network one can build an SSH connection and operate the Raspberry Pi remotely. In this measurement, the SSH connection was only briefly tested for accessibility.
| Model | Tension | Electricity | Power | Current (peak) |
|---|---|---|---|---|
| RPi A | no ethernet port | |||
| RPi A + | no ethernet port | |||
| RPi Zero | no ethernet port | |||
| RPi B | 5,134 v | 0.400 A | 2,053 W | 0.483 A |
| RPi B + | 5,146 v | 0,242 A | 1.245 W | 0.308 A |
| RPi 2 B | 5.147 v | 0.237 A | 1.224 W | 0.424 A |
| ODROID-C1 | 5,146 v | 0.225 A | 1,148 W | 0.485 A |
The power consumption of the Ethernet port is 20mA lower on the B+ model than on the B model.
Because the models A, A+ and Zero have no Ethernet port, this measurement makes no sense for these models.
Measurement 3: Raspberry Pi with WiFi adapter
In this measurement, Raspberry Pi was operated with a wireless adapter in headless mode. A connection to the WiFi was not configured.
Two different WiFi adapters for the USB are available for this measurement. The first is one in nano-construction. The second one is bigger and has an external antenna.
| Model | Tension | Electricity | Power | Current (peak) |
|---|---|---|---|---|
| RPi A | 5,148 v | 0,221 A | 1,143 W | 0.300 A |
| RPi A + | 5,151 v | 0.185 A | 0.958 W | 0.247 A |
| RPi Zero | 5,129 v | 0.179 A | 0.918 W | 0.263 A |
| RPi B | 5,131 v | 0.445 A | 2,277 W | 0.510 A |
| RPi B + | 5.141 v | 0.300 A | 1.537 W | 0.354 A |
| RPi 2 B | 5,143 v | 0.294 A | 1,512 W | 0.406 A |
| ODROID-C1 | 5.141 v | 0.288 A | 1,486 W | 0.526 A |
| Model | Tension | Electricity | Power | Current (peak) |
|---|---|---|---|---|
| RPi A | 5,143 v | 0.295 A | 1,522 W | 0.357 AA |
| RPi A + | 5,146 v | 0.254 A | 1,312 W | 0.307 A |
| RPi Zero | 5,127 v | 0,241 A | 1.245 W | 0.318 A |
| RPi B | 5.125V | 0.515 A | 2,639 W | 0.571 A |
| RPi B + | 5,137 v | 0.368 A | 1,890W | 0.509 A |
| RPi 2 B | 5,137 v | 0.368 A | 1,890W | 0.463 A |
| ODROID-C1 | 5,137 v | 0.353 A | 1,818 W | 0.606 A |
The second WiFi adapter uses around 60 to 70mA more power.
Measurement 4: Raspberry Pi with monitor and keyboard (normal operation 1)
In this measurement, Raspberry Pi was operated with an HDMI monitor and keyboard. Connection to the local network via Ethernet or WiFi was not provided for this measurement.
| Model | Tension | Electricity | Power | Current (peak) |
|---|---|---|---|---|
| RPi A | 5,146 v | 0.239 A | 1,229 W | 0.312 A |
| RPi A + | 5,150 v | 0.204 A | 1,050 W | 0.271 A |
| RPi Zero | 5,129 v | 0.089 A | 0.451 W | 0.204 A |
| RPi B | 5,126 v | 0.465 A | 2.384 W | 0.553 A |
| RPi B + | 5,136 v | 0.329 A | 1,689 W | 0.391 A |
| RPi 2 B | 5.141 v | 0.321 A | 1,650 W | 0,508 A |
| ODROID-C1 | 5,138 v | 0.368 A | 1,891 W | 0.604 A |
Here, Raspberry Pi Zero had the effect that nonuse of the keyboard did not result in power consumption. When using the keyboard, the power consumption increased by about 20 mA.
Measurement 5: Raspberry Pi with monitor, keyboard, mouse, and Ethernet (normal operation 2)
In this measurement, Raspberry Pi was operated with a VGA monitor, keyboard and mouse. To use the monitor, an HDMI to VGA adapter was used. The connection to the local network was made via Ethernet.
| Model | Tension | Electricity | Power | Current (peak) |
|---|---|---|---|---|
| RPi A | only one USB port and no Ethernet port | |||
| RPi A + | only one USB port and no Ethernet port | |||
| RPi Zero | only one USB port and no Ethernet port | |||
| RPi B | 5,120 v | 0.590 A | 3,090 W | 0.649 A |
| RPi B + | 5,134 v | 0.431 A | 2,211 W | 0.460 A |
| RPi 2 B | 5,131 v | 0.426 A | 2,085 W | 0.571 A |
| ODROID-C1 | 5,122 v | 0.552A | 2,827 W | 0.748 A |
Note: In this case, the current was measured while the mouse was being moved. If the mouse is at rest, the power consumption was reduced by approx. 32 mA.
Measurement 6: Raspberry Pi at approx. 1% CPU utilization
In this measurement, Raspberry Pi was operated with a VGA monitor, keyboard and mouse. To use the monitor, an HDMI to VGA adapter was used. The connection to the local network was made via Ethernet.
During the measurement recording, it was ensured that “top” displayed almost 1% CPU utilization.
| Model | Tension | Electricity | Performance (measured) |
|---|---|---|---|
| RPi B | 5,121 v | 0.558 A | 2,857 W |
| RPi B + | 5,134 v | 0.401 A | 2,053 W |
| RPi 2 B | 5,133 v | 0.393 A | 2,058 W |
Measurement 7: Raspberry Pi at approx. 100% CPU utilization
In this measurement, Raspberry Pi was operated with a VGA monitor, keyboard and mouse. To use the monitor, an HDMI to VGA adapter was used. The connection to the local network was made via Ethernet.
During the measurement recording, it was ensured that “top” displayed almost 100% CPU utilization. CPU usage was triggered with “sudo apt-get update” and “sudo apt-get upgrade”.
| Model | Tension | Electricity | Performance (measured) |
|---|---|---|---|
| RPi B | 5,119 v | 0.648 A | 3,317 W |
| RPi B + | 5,136 v | 0.494 A | 2,537 W |
Summary of Measure Raspberry Pi power consumption
- Raspberry Pi Zero uses less power.
- The B+ model consumes between 100 and 150 mA less power than the B model. That’s between 500 and 700 mW.
- The difference in power consumption between about 1% and about 100% CPU utilization is about 90 to 100 mA. Both model B+ and model B.
- The differences between RPi B+ and RPi 2 B are found at the second digit after the comma.
Make sure to have a look at our list of best Raspberry Pi power supply
Could you please advice, how to measure the energy consumption of Rasberry Pi 4 Model B, which is directly connected to the electric power supply through software?