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Currently connected to GPIO Pins as per guide/datasheet and it's not powering up.

Meanwhile I've got another same unit with the same simple setup/circuit except it's powered by 2 AA batteries and it's working fine.

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  • @joan Thanks. Didn't take long though for my blockage to come back along with the usual headache and anxiety related to electricity concepts. Best I could surmise from that read, the cause would be a bad connection, is that why you posted this link? If not, what else? I've rechecked the connections, unplugged, replugged, swapped Picos, cables, used different new CR2032s both cheap ones and Energizer that work fine with other devices; even triedd, with and without breadboards. At its most basic my circuit was Pico > Cable > Battery > Cable > Pico.
    – Flood
    Jul 13, 2022 at 15:36
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    Currently connected to GPIO Pins ... which GPIO pins? ... the battery should be connected to the power pins, not GPIO pins ... be aware that not all of pins in the header are GPIO pins
    – jsotola
    Jul 13, 2022 at 15:53
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    if a device works with battery A, and does not work with battery B, then the battery B is somehow inadequate ... compare the voltage rating and the supplied current for the two batteries
    – jsotola
    Jul 13, 2022 at 15:56
  • @jsstola Pins 38 and 39, are those called GPIOs? Batteries that work = AA 2 x 1.5v = 3v. Batteries that don't = CR2032s 1 x 3v = 3v. Comparing voltage rating, you mean with a voltmeter? I have one, not sure where I'd plug the ends in the circuit. At the end of the day if we're going to say CR2032s = No good with Pico W, that's fine; just would be useful to know exactly why so I can use that knowledge for future such projects.
    – Flood
    Jul 13, 2022 at 16:10

1 Answer 1

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CR2032 cell ratings depend on manufacturers, but in general a typical cell is limited to continuous 1-4mA and peak 6-12mA current draw. The Pico consumption varies widely (between ~1.5mA and ~100mA), but a typical application will need more than 4mA. The wireless module need additional current as well.

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  • I'm going to mark your response as the answer. Especially since it lead me to further research where I discovered:
    – Flood
    Jul 16, 2022 at 16:02
  • I'm going to mark your response as the answer. Especially since it lead me to further research where I discovered: - AA Batteries, when new and of the non-rechargeable type, may hold more than 1.5v for a short time; 2 days in my tests blinking the LED and displaying the temperature every 5s. So it's possible that 2 AA batteries = at least 3.3v needed by Pico. - Although I couldn't confirm that new, non-rechargeable CR2032 batteries may also give out more than their rated 3v for a short time; if they did and based on your info, they may not output the sufficient needed amps.
    – Flood
    Jul 16, 2022 at 16:11
  • @Flood In my experience a lot of 3.3V MCUs tolerate supply voltages down to 2.7V. Even the original Pi can run with just 2.7V on the 3.3V bus. Indeed, it's not as reliable as running on correct voltage, but for many hobby projects it's acceptable. Jul 18, 2022 at 11:10

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