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Since the Nano 33 boards are quite new right now, I haven't found any details on how to hook one up with batteries.

I'm pretty daft when it comes to electronics (I'm a software man), and I read that the new Nano 33 requires 3.2V, which is a bit of a departure from the 5V the old models supported.

From what I can tell, I might be able to use a single LiFePO4 cell. Am I correct in this assumption? And if so, are there any pitfalls in going this route?

EDIT: I might have misunderstood the difference between operating voltage and input voltage. Does this mean that I can plug any AA battery pack in as a power source?

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You can either use the 3.3V pin to supply power to the board, or use the Vin pin.

By using the VIN pin to power goes through a (step down) voltage regulator, that provides a nice stable 3.3V to the board. The regulator in the Nano 33 IoT is the MPM3610, which requires an input voltage of at least 4 - 4.5 Volt. Which is more that a LiPo or LiFePo single cell can supply. You could use a multi-cell battery pack. Or a USB power bank. So this solutions is not really ideal.

The other option was to connect the battery directly to the 3.3V pin. The voltage of a LiFePo however changes as it is being discharged. The voltage is around 3.65V when full, and 2.5-2.75V when "empty". The 3.2V rating is called the nominal voltage (kind of an average voltage). So it's a bit too high when full, and too low when empty. The voltage also isn't regulated, so it can fluctuate a bit, based on the amount of current that's being used.

The maximum voltage for the SAMD21 on this Nano is 3.63V. Maximum voltage for the gyro (LSM6DS3) is 3.6V. The absolute maximum voltage for the radio (NINA-W10) is 3.6V.

So a full LiFePo is slightly too high for the Nano. Though I think you should be fine. But don't try this with a regular LiPo of Lion battery (4.2V when full).

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  • Thanks so much for replying to my question. Do I understand correctly that I could use three 1.5 volt AA batteries connected in a serial fashion to power the nano via the VIN pin? – Nailer Oct 4 '19 at 11:13
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    Not quite. If you take 4V as the low point for voltage regulator, it would stop working if the batteries reach 1.33V, using only around 10% of the AA's total charge. I'd use at least 4 AA cells. Since it's a switching regulator it doesn't really matter what voltage you give it as long as it's between 4V/4.5V and 21V (unlike a linear regulator that just wastes the extra voltage). I'd go for 6 AAs. That way you can run them totally flat. The regulator is also a bit more efficient at a higher voltage. – Gerben Oct 4 '19 at 15:40
  • Thanks a lot! That's exactly what I needed to know. – Nailer Oct 7 '19 at 8:42
  • I tried running the board with ~9.5V from 6 AA batteries, and while it did power up, the BLE module seems not to be working. I'm trying to figure out where to go from here by posting in the official Arduino forums. – Nailer Oct 8 '19 at 15:44
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    Haha! I think it was me leaving the "wait for serial" code in the example, which doesn't go past while(!Serial). Sorry, that's a stupid mistake from my part. – Nailer Oct 9 '19 at 7:10

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