I recently purchased a USB device that can measure both current and voltage (i.e., it functions as a voltmeter as well as an ammeter) and decided to use it to determine how much power my Raspberry Pi Model B typically consumes. Figure 1 shows what it looks like.
The Raspberry Pi website claims that the Model B requires to operate and draws a current between and (depending on the peripherals connected). My voltage measurements were consistently close to , but my current measurements were below the advertised range, even when the Raspberry Pi was under heavy load (e.g., during boot time).
Fig. 1:Measured current (a) and voltage (b) used by a Raspberry Pi Model
B. The values shown are and
, respectively.
With measured values for the current and the voltage , one can calculate the power consumption of a device using the following formula:
Using the values from the Raspberry Pi website ( and ), we get:
The highest current and voltage values I observed were and , respectively, meaning the maximum amount of power consumed by my Raspberry Pi was:
which is significantly lower than . Under normal load, my Raspberry Pi consumed between and .
