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I've been playing around with my Pi on a battery recently. I have the Pi set up so that I can SSH into it. Using the standard commands(sudo shutdown -h now) to shutdown work at bringing the Pi down, but because I am across SSH, I have no idea when it is good to pull the plug. The Pi then reboots, as it's receiving power. At which point I can log back in over SSH and start over.

Ideally, I would like it if my Pi stopped pulling power after the halt, as my battery automatically shuts off after 10 seconds of no power drawn. But, If I could just figure out when it would be safe to manually pull the plug, I would be happy.

TL:DR How do I determine when I can pull the power from a Pi not connected to a screen? Is there a way for it to not draw power after shutting down?

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    On a sidenote; sudo halt does the same and is a lot faster to type. – Gerben May 3 '14 at 19:03
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It depends somewhat on your distro and how you've configured the Pi (some software may include commands that get run on shutdown).
If you can temporarily attach a monitor, time it a few times and then add a few seconds to the longest time you observe. If you can't attach a monitor, but if you can see the LEDs, you can wait until only the red one is lit, and then a few seconds more. If you can't see the LEDs, 45 seconds from when your SSH session is disconnected is probably plenty.

  • Second that. Just wait 3 seconds after all leds have stopped blinking, and only the red one is still on. – Gerben May 3 '14 at 19:01
  • I'm using a Pi specific UPS and that waits 40-ish seconds after pulling a dedicated GPIO pin low before killing the power to the Pi so I suspect that 45 seconds is a good figure to use. – SlySven Dec 18 '15 at 0:36
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The correct shutdown and power-off command is

sudo shutdown -hP now

The Pi will continue to draw power (I don't remember how much, perhaps 125mA) even after power-down.

If you are powering from a lipo you'll need to disconnect the battery, otherwise it will drain the cells and the battery will be useless.

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