For various projects where a long runtime with batteries is important I use a modify Arduino Pro Mini 328 3.3V/8Mhz (ATmega328P). As an example a flashing sketch is used, which turns the LED on for 1 second and off for 8 seconds.

Blink sketch

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  delay(1000);
  digitalWrite(LED_BUILTIN, LOW);
  delay(8000);
}

To optimize the power consumption the Arduino Pro Mini is put into DeepSleep instead of waiting 8 seconds.

DeepSleep sketch

#include "LowPower.h"

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  delay(1000);
  digitalWrite(LED_BUILTIN, LOW);
  LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);
}

Modification

In order to optimize the power consumption more, I modify the Arduino Pro Mini. For this I unsolder the power LED and the regulator. The ATmega328P can support voltage levels between 2.7 V and 5.5 V and this is perfect for my projects, because I use 18650 Li-Ion batterys as power source.

Results overview

Links

• LowPower librarie: https://github.com/rocketscream/Low-Power