Raspberry Pi power supply

Executive summary: Always use the official Raspberry Pi power supply. Never use USB chargers.

Before the official power supply was introduced, selecting one (especially for later Pi models) used to be challenging, as many of the easily available USB power supplies were cheap phone chargers unable to provide a stable voltage when the current increases. Also it turned out that specs printed on packaging materials were usually bogus.

The only way to choose a suitable power supply reliably is to test and measure it.

My testing method:

use Raspberry Pi 3 Model B with the built-in WLAN enabled
boot Linux with serial console from MMC card
scan WLAN networks in a loop
generate 100% utilization on all ARM CPU cores
measure the voltage from an USB port
check that the red LED does not blink / turn OFF (undervoltage)

Marketing name/vendor	Small print	Rating	Measured V	LED
Raspberry Pi Universal PSU	DSA-13PFC-05	5.1V/2.5A	5.13 V	ON
Vanson USB Power Adaptor	SMP-500A005USB	5.0V/1.0A	4.89 V	ON
Clas Ohlson USB Charger (36-5756)	SP-5USBi-EU	5.0V/2.4A	4.80 V	ON
Google Chromecast PSU	5005BBV0500100	5.0V/1.0A	4.80 V	OFF
HTC	TC P900-EU	5.0V/1.5A	4.77 V	OFF
Nokia 6 charger	FC0100	5.0V/2.0A	4.69 V	OFF
Nokia charger	AC-50E	5.0V/1.3A	4.65 V	OFF
Verkkokauppa.com TinyCharge	CEUL502100	5.0V/2.1A	4.64 V	OFF

Last updated: 2023-12-29 11:19 (EET)