13

For how long can the Raspberry Pi run when powered from a battery of a given capacity?

Of course this will strongly depend on how it is used and what devices are connected, but I am trying to get a rough estimate for my use case, to be able to decide what battery to get (while trying to keep the budget low, I don't want to go straight for the 12000 mAh option unless necessary).

I am using it to take a timelapse with raspivid with 2 fps. CPU usage is always low (< 10%), but I guess GPU usage and the constantly active camera influences the battery life too. No devices are connected except for the Pi camera. Perhaps someone already has experience with a similar situation.

Alternatively, how can I measure the power usage of the Pi under actual usage, to estimate the battery life myself? I do have a multimeter, but breaking the power circuit and inserting a multimeter to measure the current seems like a lot of trouble, especially since it would involve destroying the power cable.

Szabolcs
  • 662
  • 2
  • 6
  • 18

2 Answers2

10

The pi can't draw more than 1A due to a fuse stopping the board drawing more than that. So how big a battery you need really depends on how long you want it to run. If you have a 500mAh battery, that will output 500mA (0.5A) for one hour, or 1000mA (1A) for half an hour. Similarly, a 2000mAh battery will give you 2000mA (2A) for one hour or 1000mA (1A for two hours). So really it's up to you, your battery, and your budget.

Luke M
  • 747
  • 1
  • 7
  • 17
2

What run level are you using ? I suggest run level 3 - turn off all the graphics. Have you turned off/disabled unwanted/not needed services?

These guys claim to have got 15 hours from a 3000mAh battery using the pi camera board with a model A to capture stills every 10 seconds http://www.rs-online.com/designspark/electronics/eng/blog/time-lapse-photography-with-the-raspberry-pi-camera?/designspark/electronics/blog/time-lapse-photography-with-the-raspberry-pi-camera=

For measuring current

Did you solder directly or connect the battery to the dc connector on the rpi? If the dc connector, just make an extension cable with breakouts to from multimeter.

Can get current monitor chips/sensors with i2c control, could make the pi monitor its own current use. spark fun and adafruit sell some premade boards www.adafruit.com/products/904 www.sparkfun.com/products/8883 (sorry not enough rep to yet post links)

lxx
  • 181
  • 4