12V Battery for Nanos and Relay Board

Using Arduino General Electronics
1

Hi,

I'm planning to power two Arduino Nanos and a relay board with a VariCore 12V 3000mAh 18650 Li-Ion battery. The relay board will switch a 12V circuit, and I'd prefer to use a single battery for the entire setup.

I'm considering using a step-down converter to power the Nanos (which operate at 5V) from the 12V battery. My concern with using a step-up converter to power everything from a lower voltage battery is the potential current draw of around 0.5A at times from the 12V circuit.

Does this approach make sense? Is there a better way to power my setup?

Thanks in advance for your help!

2

I moved your topic to an appropriate forum category @JC7A3 .

In the future, please take some time to pick the forum category that best suits the subject of your topic. There is an "About the _____ category" topic at the top of each category that explains its purpose.

This is an important part of responsible forum usage, as explained in the "How to get the best out of this forum" guide. The guide contains a lot of other useful information. Please read it.

Thanks in advance for your cooperation.

3
  • We need to see a schematic of what is proposed.
4

Here's a quick sketch of my setup. It's simplified to show the basic idea – the resistor represents the 12V battery. I've omitted some connections for clarity, and the LCD isn't shown accurately.

The key point is that I have 16 relays and 16 buttons, not just one of each. I hope this is enough to understand what I'm trying to achieve.

image
image626×469 28.9 KB

5

  • You need to communicate exactly what you are proposing.

  • Please spend some time making a schematic which we can read terminals and easily follow, don’t leave anything out..
    A schematic is the universal language we use the communicate what’s happening.

  • A NANO can be powered either by the RAW pin or by the 5v pin.
    The relay card must be configured properly for 5v operation.

  • We need accuracy and a proper schematic showing all connections.

6

Yes, generally it's preferable to power the highest power draw without converters and use buck for smaller loads. But make sure that 3S battery nominal voltage ~11V (down to 9V) is enough for your application.

7

Are you using relays with 5 volt or 12 volt coils?

8

Is there some form of controller in that battery pack? Pictures on AliExpress makes me think it is just three batteries in series, which doesn't give you 12V (12.6V fully charged; 10.6V nominal; 9V discharged).

You are right in thinking to start high and use buck converters to lower the voltage.

9

Why two? This is usually a beginner's mistake.
Communication between the two adds another layer of complexity.
Use one, and a port expander. Or search for a relay board with port expander.

16 5volt relays draw 16 * 75mA = 1.2Amp.
12volt relay coils might simplify your setup and buck converter choice.
Leo..

1 Like