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If you didn't already know, you can power the Pi from the GPIO pins. By supplying pin 2 with 5v and connecting a ground to pin 6, you can power the Pi. My question; does it matter which pins are used? Could I use pin 4 for 5v and pin 14 for ground? (Really I'm just interested in if I can use a different ground pin.) Also, what is the max current that can be drawn when powered via GPIO, my Zero can draw up to 180mA, so I want to make sure that this is safe. Why or why not is this the case?

All my pin references came from the picture below.

enter image description here

  • If you take a multimeter and set it to "Ohm" position, then test GND points, you will find that GND, is all connected. It is a solid plane, it is not separated any where. Even the USB metal parts and any other metal parts are connected to GND. The headers should really be used to power external circuits. If you are running into problem where you need more amps for something, your are overdoing something. The USB circuit on newer Pi's is more than sufficient. So you can use any GND you like but it recommended to power the Pi from the USB "side" – Piotr Kula Feb 12 '16 at 8:54
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All the pins are connected together. As to whether it is safe it depends on the power source (and partly your definition of safe). AFAIK the Zero has no power protection (there is no published circuit).

  • Let's assume my power supply can supply a perfect 5.2V with max 500mA. – Patrick Cook Feb 12 '16 at 3:30
  • There is no such thing as a "perfect" PS. Provided it is stable, well regulated and 5±.25V it should be OK. The other Pi have polyfuse and transient overvoltage protection. – Milliways Feb 12 '16 at 3:42
  • I know it can't be perfect. I just wanted to know if the Pi would have a problem, not the power supply. – Patrick Cook Feb 12 '16 at 3:56
  • I ended up stripping a micro usb cable and connecting the two leads to the PS and the micro usb to the PWR input, just felt safer to go with the power protection. – Patrick Cook Feb 23 '16 at 0:22
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You can NOT power the Pi from GPIO.

You can power via the power rail pins on the expansion header.

All the pins on the same power rail are connected together.

It does not matter which particular 5V pin or ground pin you use.

  • Do you know the max amperage? All I know is that the max output of the rail is 50mA total. – Patrick Cook Feb 12 '16 at 7:44
  • Power rail pins are not GPIO. GPIO stands for general purpose input output. – joan Feb 12 '16 at 8:44

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