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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.

marked as duplicate by lenik, RPi Awesomeness, kolin, Bex, Lawrence Jul 28 '14 at 9:18

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  • 2
    I got a 4000mah battery (and asked a question about it here), and it works for an hour or so - I always try to turn it off before the charge indicator gets to low. I use with the GPIOs turning on and off transistors on a (separately-powered) robot motor controller, USB webcam taken out of a broken netbook, with a webserver plus a few CGI scripts controlling it. – Wilf Jul 2 '14 at 16:50
  • @Wilf Thanks! 1 hr is much less than what I was hoping for :-( You seem to have WiFi module attached. Doesn't that eat a lot of battery? And doesn't 4000 mAh meah that it would need to give 4000 mAh to discharge fully in just one hour? The Pi is supposed to use less than 1 A, possibly just 500 mA when used with no peripherals. – Szabolcs Jul 2 '14 at 18:10
  • thats for a robot with USB webcam, GPIOs controls and camera data being sent constantly over wifi (power-save disabled) at 15fps (still slow) on top of a Apacke web server. It should last alot longer, but I haven't measured it :) – Wilf Jul 2 '14 at 19:03
  • Why don't you just feed power in via the 5V and ground pins on P1. Can't you butcher another PSU or wall wart to get the power? Then you could take measurements with your meter. – joan Jul 2 '14 at 21:34
  • Downvoter: explain your downvote please. It achieves nothing without an explanation. – Szabolcs Jul 3 '14 at 3:36
up vote 8 down vote accepted

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.

  • I did not know about the 1 A upper limit, that is useful. Do you have experience with batteries? Does a 1 Ah battery really last for 1 hour in practice while continuously drawing 1 A, or are there any subtleties I should be aware of? (I.e. do batteries really work the way one would naively expect based on the charge rating?) – Szabolcs Jul 3 '14 at 17:04
  • 1
    Raw LiPoly batteries like the ones adafruit sell are quite tricky to get working and are quite expensive for the amount of charge they hold. Consumer products, however like 'backup batteries' for smartphones and tablets, are generally cheaper, and have all the voltage-regulating circuitry built in. – Luke Moll Jul 3 '14 at 17:16
  • You are confusing amps with power here, this is only true of a 5V XmAh battery, most Lipo batteries are 3.7V. – gubby Jan 7 '17 at 17:53

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

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 (sorry not enough rep to yet post links)

  • I am not looking for ways to reduce power consumption. That is given and I am not willing to change it. I am looking for information that will help me decide on which battery to get for a Model B. – Szabolcs Jul 3 '14 at 3:18
  • What runtime do you need ? What weight/size do you have to fit the battery into ? and what cost ? – lxx Jul 3 '14 at 3:24
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    I'd strongly disagree on not needing to reduce power consumption, by some really simple things you can save a lot of power over a stock standard raspian software image – lxx Jul 3 '14 at 3:43

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