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I use a 3023 Keystone electronics, through-hole coin cell holder in my circuit. When I connect the Arduino to my computer, it gets powered up without any issue and my circuit works just fine.

The problem is that when I disconnect it and try to place batteries in my coin cell holder, it does not work, the Arduino's lamp doesn't blink and my circuit doesn't work. The circuit has two load cells, a load cell amplifier, an Arduino, and a coin cell holder.

I don't know if I have to but I thought I heard I had to make different types of wiring on the board for power lines? If not, could it be because I soldered it in the wrong direction?

I tried multiple different batteries but that doesn't seem to be the problem either. I use two 2032 Philips cells in my holder which should give 6 V, the required voltage for the Arduino (33 IoT) to work.

This is the schematic of my circuit:

board schematic

This is the board:

board

This is the actual board:

board image

board image

board image

board image

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    \$\begingroup\$ Have you measured supply voltage at Arduino power input? \$\endgroup\$
    – Justme
    Jul 19, 2022 at 8:06
  • \$\begingroup\$ Do you have a contact plate on the pad marked '3 GND' or is it just the bare pad? What is the expected current draw? \$\endgroup\$ Jul 19, 2022 at 8:07
  • \$\begingroup\$ There is a contact plate on the board, it is not marked 3 GND though. In the datasheet it says the current consumption of the load cell amplifier is for: normal operation < 1.5mA, power down < 1uA. \$\endgroup\$
    – tomcajot
    Jul 19, 2022 at 8:25
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    \$\begingroup\$ Check that the contact pad on the board is making contact with the cell. It may be that the solder mask is higher than the metal and preventing the battery from touching it. Squeeze a small bit of tinfoil or something between the two. \$\endgroup\$
    – Finbarr
    Jul 19, 2022 at 8:55
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    \$\begingroup\$ Check the supply voltage after it's been running for a while. I suspect you're being ambitious trying to power the circuit with two coin cells. \$\endgroup\$
    – Finbarr
    Jul 19, 2022 at 10:19

1 Answer 1

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The Arduino® Nano 33 IoT apparently (the present official datasheet is not informative) draws current of 40-50mA.

A CR2032 cannot supply that much current, even briefly, and maintain output voltage. A stack of AA batteries would be better, and you'd probably want to activate whatever power-down features it has to minimized current draw when it's not necessary.

One indication that this Arduino is not a particularly low-power device is their choice of a switching supply rather than the linear regulator used in the basic ATmega-based nano.

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  • \$\begingroup\$ What board do you recommend using? I just need to read the data from the load cell amplifier and send it via bluetooth. \$\endgroup\$
    – tomcajot
    Jul 19, 2022 at 13:00
  • \$\begingroup\$ Anything with a transmitter is going to take some juice during the transmit, at least. Some car fobs are powered by a CR2032 however they also have a tiny lithium-ion rechargeable battery to supply the peak current (and the circuitry is designed to draw uA in standby (when a button has not been pushed recently). Depending on how your device is intended to be used, that may not be possible. It's possible if you found a suitable device with BLE a battery or supercapacitor could be used to supply the juice for milliseconds during the transmit. \$\endgroup\$ Jul 19, 2022 at 14:22

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