Arduino Vin, 5v or 3.3v with 18650 battery

Projects General Guidance
1

I'm powering an Arduino Nano with a single 18650 battery. I'm prepared to use a Step Up Converter (found here) if best case. I'm simply powering a 5v LED. What is the recommended voltage input pin?

Thank you in advance.

2

The input voltage range of the VIN pin of Arduino Nano is 6.5 - 12v

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3

Never seen one. Feel free to explain better.
"neopixel" ?

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4

Did I identify the LED incorrectly? This is it:
Amazon.com: POCREATION 25Pcs AXD-1W-5V LED Chips, 5V LED Chip Bulb, 200LM 1W High Power LED Lamp Beads for DIY Lighting Fixtures(Warm White 30003200K) : Industrial & Scientific ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_6

5

1W LED..
And how are you planning to power it with arduino?

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6

Do you intend to turn the LED on and off?

7

A single 18650 battery with a step up converter if necessary.

I guess that even with a step up converter, the Vin pin can't be used. Is there and advantage the 3.3v pin over the 5v pin as input? will one last longer than another before recharging is needed?

8

All right! Is everyone in the mood for a game of 20 questions?

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9

It's ok for powering arduino and the LED, but arduino is not capable of controlling that LED without additional circuit.
That LED draws about 300mA, while Arduino can give less than 1/10 of that. You need some transistor/mosfet circuit to switch it by arduino.

Edit: After your post edit I don't know what to answer...

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10

You cannot power the Nano via the 3.3 pin, it's an output only. Suggest you look at the Arduino schematic at Arduino.cc, all will be revealed.
This also might help you.

And this; although they do discuss using 3.3V pins as inputs, it's only intended to be done for 3.3V processors, which the Nano is not.
https://docs.arduino.cc/learn/electronics/power-pins

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Thank you for this answer. This is a very informative article.

Snarky. What was in the original post that you found deficient?

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Usually you can use an LiIon connected directly to +5V to power an Arduino (and LED.)

Note that this provides no protection for the battery - if the battery doesn't have its own protection circuit, the Arduino will happily discharge it till it won't charge again. (Theoretically, you can have the Arduino warn about low voltage and reduce power consumption.)

A boost converter (to +5, connected to +5) that includes protection is probably safer. Note that many of the inexpensive boost converters are designed for implementing "phone charger boost packs", and will turn themselves off if your circuit consumes too little power.

Also, of course, an Arduino can not directly drive a 1W led (~300mA worth. An Arduino output is good for about 30mA, and the whole chip has a limit of about 200mA.) (It looks like those LEDs have a built-in resistor for working with 5V. nice!)

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I didn't want to clutter up the original question that I had with extraneous information. In past configurations to power the 5v LED using 2S, 3S, 4S and 2 18650 batteries using a voltage regulator and voltage divider. The LED is turned on and off with a TV IR remote. Way too complicated and too big. The LED worked great. Long life and bright.

To simplify, now I'm going to use a single 18650 battery connected to a TP4056 charging board to protect the over-discharge of the battery and a step-up converter to use the 5v output pin.

Thanks all for your responses.

14

I suggest you get a copy of the Arduino Cookbook and skim it cover to cover and stop on the many sections that apply to your project.

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15

You can get a module that includes all parts of your circuit, including even the battery holder. I posted about it in this thread:

https://forum.arduino.cc/t/at-last-18650-charge-boost-module-with-load-sharing/1164462/16

It has the battery holder, USB charging input, a TP4056 charger, a protection circuit, a load sharing circuit, and a boost converter. You would need to add a 100uF capacitor across the charging input, and an on/off switch between the charger and boost sections. See post #1 in that thread for Aliexpress links. This is a UPS module, not a powerbank module, so it doesn't shut down with too little current.

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Thank you ShermanP. This does 2 tnings for me:

1 - Your post provides another option for me and...
2 - It validates my approach which I need because of my inexperience.

Thanks again.

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