Power consumption on the Raspberry Pi is something we have to consider when building Pi projects. This is especially true when those projects are powered from batteries. Knowing how much current your Pi is going to draw allows you to determine what batteries to use and how long it is likely to run.
In this post we’ll present the results of our Pi power measurements. The models tested were :
- Pi A+
- Pi B+
- Pi 2 B
- Pi 3 B
- Pi 3 B+
- Pi 3 A+
- Pi Zero W
In order to measure the current draw by the Pi we used a PortaPow hand-held current and power meter. It can measure the milliamp-hours used over a specific period of time. We tended to run a test for 10 minutes and multiply the milliamp-hour total by 6 to get the average current used. Taking an average helped smooth out any fluctuations and gave a more reliable value.
The Pi was connected to a monitor (via HDMI) and a keyboard (via USB). Where available the on-board WiFi was enabled for some tests. The November 2018 Raspbian image was used as this allowed us to test the newly released Pi 3 A+.
For each device I measured the current for the following activities :
- Raspbian desktop (WiFi disabled)
- Raspbian desktop (WiFi enabled)
- Playing a 1080p MP4 using OMXPlayer (WiFi disabled)
- Playing a 1080p MP4 using OMXPlayer (WiFi enabled)
- Watching a YouTube video in the Chromium browser (WiFi enabled)
Pi Power Consumption Results
The Pi Zero W has the lowest power consumption whereas the Pi 3 B+ (2018) has the highest. The newer Pi 3 A+ is slightly lower than the B+ but only if the on-board Wi-Fi is disabled.
The original Pi Zero is almost identical to a Pi Zero W with the WiFi turned off so is not included in the my data. The Pi Zero couldn’t really handle the YouTube video test so that has also been excluded.
Booting to the command line rather than the desktop resulted in an idle consumption that was usually 5-10mA lower than the Desktop Idle figure.
Factors Affecting Power Consumption
Here are things to consider when judging the power consumption of your Pi :
- Attached USB devices draw power from the Pi’s USB ports
- Keyboards and mice draw different current depending on their brand or design
- On-board WiFi and Bluetooth will draw power unless disabled
- Pi Models with multiple cores will use more power as those cores are put to work
- Items attached to the GPIO will draw power through the 3.3V and 5V pins
Although the newer Pi models come with extra performance, that can sometimes be at the expense of power consumption. If you are creating a battery powered project you should consider which model is best suited. Using a Pi 3 B+ may not be the best choice from a power point-of-view.
Buy a Power Meter
The meter we used for our tests is a PortaPow Premium DC Power Monitor. There are plenty of alternatives available on Amazon.