Estimating Battery Life

To get some  battery life estimates for my battery board V2 project, I decided to use my arduino battery tester to measure the 5V current draw on the model A and model B Raspberry Pi.  You can see my test setup below:

I found that a model B Raspberry Pi running Xbian, without an ethernet connection, at idle (on a file menu screen) would draw about 370 mA.  For a model A Raspberry Pi under the same conditions the current draw was about 170 mA.  In a more practical test, with the model B Raspberry Pi running Xbian to stream  a 720p HD video over a USB WiFi adapter, the current draw was about 570 mA.  Running the identical video streaming  test on a model A Raspberry Pi showed a current draw of 350 mA.  Note in my current measurement tests all measurements are approximate values since the current draw fluctuates quite a during the test.  Also my measurement accuracy probably is probably in the range of +/- 20 mA. 

I am also considering the use of the CSI camera board in some of my portable Raspberry Pi projects so I took  a quick measurement of the current draw in Wheezy at idle and with the camera capturing a short h264 video clip.  At idle the camera equipped  model B board drew about 400 mA.  With the camera capturing video the model B drew 670 mA – an additional 270 mA while recording.  Removing the camera board didn’t change the current much.  So the camera doesn’t seem to use much power unless it is doing something.

So I can estimate that a Model B board with WiFi and active camera would draw about 570 + 270 = 840 mA.   A Model A board with WiFi and active camera would draw about 350 + 270 = 620 mA

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