Arduino resets and unstable behavior when powered by 3×18650 battery pack through LM2596 and barrel jack with multiple modules

Projects General Guidance
1

I want to explain my setup clearly from the beginning because I am having an issue and I am not sure what is causing it.

My Arduino is powered by a 3×18650 lithium battery pack connected through an XY L30A battery charging control module. From the battery output, I connected an LM2596 voltage regulator and set it to 5V. Then I connected that output to a DC jack adapter and plugged it into the Arduino barrel jack.

The Arduino does turn on, but it starts blinking unexpectedly and sometimes the buzzer or speaker makes random sounds. This makes me think the power is unstable.

I think there might be two possible issues. First, since I am using the barrel jack, maybe 5V is too low and I should increase it to around 7 to 12V, maybe 8V. Second, I am using many components, so there might be voltage drops or current issues, especially with the DFPlayer and speaker.

These are all the components in the system:
LCD screen
Joystick
Buzzer
DHT11 temperature and humidity sensor
RGB LED module
Water sensor
Soil moisture sensor
DFPlayer
Speaker
Ultrasonic sensor

What could be causing this issue and what would be the best way to fix it?

2

And there's your problem. The barrel jack is not a 5V input. Up the voltage going in there to at least 7V.

3

How about the voltage drops and power instability? I think the DFPlayer MP3 module and speaker might be causing most of the problem.

4

You ask a question then ignore the answer? Sorry, I didn't realize you had already made up your mind. Good luck, I'm done here.

5

I’m not ignoring it, I’m just making sure that if I change it to 8V it would not damage anything.

6

Thank you.

7

The barrel jack on an Arduino Uno is the input to a 5V regulator, the output of which goes to the 5V pin. That regulator requires headroom of a couple volts to operate properly. So you should increase the voltage there to 7-8V. But then the question is how you are powering all the other parts. Do they require 5V? If so, you should not expect the Uno's regulator to provide much power. Can you post a drawing of how you are powering all these devices?

8

Yes, you'll damage your other components if they're connected directly to the same power supply. Therefore, before discussing anything further, we need a diagram of your connections with all lines, including power and ground, and labeled pins indicating exactly where everything is connected.
Discussing any issues without a diagram is pointless.

9

Spend some time getting to understand how the Arduino boards are powered and can supply power.

With that collection of sensors and devices attached, you need to be careful how it all goes together. Use the board to control and keep all the attached stuff powered separately.

Out of interest, what is the project all about?

10

Your solution is post 2.

11

Have you read the specs in the Arduino docs hardware section?

Screenshot 2026-04-23 at 08.32.42
Screenshot 2026-04-23 at 08.32.421090×110 4.53 KB