qwertyuiopzxcvbnm
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Powering a Pi Zero directly from 3AA batteries

Sat Aug 20, 2016 1:08 pm

I saw some tests in another thread about powering the Pi Zero from a source down to 2.9V. I'd like to ask what the implications for the 3.3V sections of the Pi Zero are when powering at such a low voltage (for instance, will the GPIO pins output a high value of 2.9V, or will they just stop working). Does anyone know what the lowest input voltage for the Pi Zero is, while keeping the 3.3V regulator working reliably?

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davidcoton
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Location: Cambridge, UK

Re: Powering a Pi Zero directly from 3AA batteries

Sat Aug 20, 2016 1:28 pm

If you are powering from 3 cells, the nominal voltage is 4.5V. By the time they drop below 3.3V they will be dead (not enough current available for a Pi0).
I don't have the regulator spec, but it probably needs at least 3.5V input to keep the 3.3V happy. If the 3.3V rail does dip, the GPIO will still work but will find it harder to drive the outputs reliably. Other parts of the circuit may not be reliable either.
With a source below 4.75V, you can expect problems with HDMI and any attached USB peripherals.
YMMV.
Location: 345th cell on the right of the 210th row of L2 cache

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TimG
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Location: Switzerland

Re: Powering a Pi Zero directly from 3AA batteries

Sat Aug 20, 2016 2:41 pm

Regulator drop-out is very low on the Zero. I measured 4.3mV at 94mA.

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Gavinmc42
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Joined: Wed Aug 28, 2013 3:31 am

Re: Powering a Pi Zero directly from 3AA batteries

Sat Aug 20, 2016 2:46 pm

Power section Zero was designed for Dave and his balloons?
Seen a pic with AA's.
Any WiFi modules that would work on that voltage?
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges

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HermannSW
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Joined: Fri Jul 22, 2016 9:09 pm
Location: Eberbach, Germany

Re: Powering a Pi Zero directly from 3AA batteries

Sat Aug 20, 2016 3:44 pm

I have powered an Arduino Uno with LCD Keypad Shield with a single AA battery (and a 5V step-up converter) -- should do for Pi Zero as well:
http://forum.arduino.cc/index.php?topic=399151.0
Image
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Location: Eberbach, Germany

Re: Powering a Pi Zero directly from 3AA batteries

Sat Aug 20, 2016 4:53 pm

I was wrong, even 3 AA batteries did not work to power Pi Zero.

But I remembered the 30C Lipos (25C will do as well) I do use for high speed motor experiments -- a single fully loaded cell (4.2V, although nominal 3.7V) is enough to power Pi Zero plus a ILI9341 TFT display:
Image

Hermann.
https://hermann-sw.github.io/planar_graph_playground
https://stamm-wilbrandt.de/en#raspcatbt
https://github.com/Hermann-SW/memrun
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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