Arduino Nano + DFPlayer Mini resets when powered by batteries (works fine on USB)

Projects General Guidance
1

Hi everyone,

I’m new to the forum.

System works on USB but DFPlayer fails to start when powered by batteries.

Hardware:

  • Arduino Nano
  • MPU6050
  • DFPlayer Mini + speaker
  • WS2812B LED strip (144 LEDs)

Components:

Behavior:

  • USB power → everything works
  • Battery power → DFPlayer fails

Tests:

  1. 2x 18650 (parallel) → 5V pin
  2. 2x 18650 (series) → VIN

Result:

  • Arduino ON
  • MPU6050 ON
  • DFPlayer LED blinks briefly then OFF
  • No boot sound

Notes:

  • LED strip only turns on after button press
  • 2200µF capacitor already added to DFPlayer power
  • Components are generic
  • Circuit is soldered but can be rebuilt

Batteries:

  • Tested with used laptop cells and new “Sony” cells
  • All between ~3.65V and ~3.8V

Suspicions:

  • Possible power instability affecting DFPlayer??

Questions:

  • Is this a power/current issue?
  • VIN vs 5V relevant here?
  • Is DFPlayer sensitive to voltage dips?
  • Can this be solved in code or only hardware?
  • Even with a 2200µF capacitor, should I add regulation? (++)

I can provide schematic and code if needed.

Thanks.

2

That's not going to work. 3.6V into the 5V pin?

And I'm sure someone will be along to strongly advise against putting Lion batteries in parallel.

You should have done that already. Not doing so up front is simply wasting time.

3

Neither option is suitable without an additional power converter.
Supplying 3.5V to pin 5V has already been mentioned by @van_der_decken – an Arduino Nano, DFplayer, and LED strip won't work this way.

Regarding supplying voltage from two series-connected batteries to the VIN pin, in this case, all your loads will be powered by the Nano's voltage converter, which has relatively low power and won't provide a stable supply.

You need a separate voltage converter for the 18650, which you will then use to power all the other modules in the circuit.

Example

4

This will work

image
image774×548 141 KB

5

I thought since it works fine when powered by usb, code wouldnt be a thing... but im going to upload to github then link it here
ty!

6

thats my next step then! ty jim

actually, i thought about stepping it up when in parallel 3.7 to 5v

7

thats my next step then! ty b707

8

NEVER put batteries in parallel!
Besides the 5V output of a boost may not be clean enough to power the Nano. The two batteries in series will provide a nice clean power source to the Nano

10

This will work

Interesting that it’s 7.4V to the Nano and 5V to the rest... why not 5V to both the Arduino and the modules?

11

I frequently use a single 18650, boost it to 5.0 V, and supply both Nano and DFR Player with that, avoiding the Nano's regulator.

12

Since I already have those parts (the step-up and the 18650) on hand, I’m tempted to try that before going with 2S + buck

13

See post #8
Plus you wont have any reset problems with your set-up