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Topic: MKR1000 doesn't work with 3.7V LiPo battery (Read 3916 times) previous topic - next topic


Try to use a MKR 1000 powered by a  3.7V LiPo battery. But it doesn't work.

If I connect 5V via USB, the MKR1000 runs. If I connect the battery additionally, the charing LED turns on and switches from red to green if the battery is fully charged. If I disconnect the USB power (the battery is still connected!) the MKR1000 switches off. Sometimes the power LED is blinking weakly.

How can I use the MKR1000 with battery power? Do I have to change something in the code?

Currently I have no idea  :(  Can somebody please help me ?


The LEDs are designed to turn OFF when on battery power to conserve energy.

As a test power up and load up the BLINK sketch but change the flash frequency.
Connect the battery and let it charge fully.

When its charged then disconnect the USB.
The L LED should continue to flash for some time.

There is also a minimum batter size recommended in the specs.
Ensure you batter meets or exceeds that spec.

1100 mH I think
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google (who would have thunk it ! ) or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.


I'm having the same issue. 

I've loaded up the Wifi101 library and an attempting to turn the LED on and off via a browser.  My lipo battery is fully charged.  When the MKR1000 is plugged in and using the USB, the board runs perfectly.  When I then pull the USB out and let it try to run on battery there is nothing.

Any help with this would be appreciated.  I would like to eventually move my project to run on solar during the day and battery at night.

I'm using the adafruit 3.7v 2500mAh battery.



@ both of you LOL..

Make sure you don't have the WHILE SERIAL statement enabled in the sketch that neither of you posted.

To jenz  removing the USB connection will also reset the serial port and I think that might be what you are seeing. Unfortunately I don't think there is a way around that.

It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google (who would have thunk it ! ) or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.


I am having the same issue. Any advice is appreciated. Sketch below.

#include "arduino_secrets.h"
#include <WiFi101.h>
#include <RTCZero.h>
#include "ThingSpeak.h"

const char* ssid = SECRET_SSID;    //  your network SSID (name)
const char* password = SECRET_PSWD;  // your network password
String httpsRequest = SECRET_REQUEST; // your Blynk API token

const char* host = "hooks.zapier.com";
WiFiSSLClient ZapierClient;
WiFiClient  ThingSpeakClient;

unsigned long myChannelNumber = SECRET_CHANNEL_NUMBER;
const char * myWriteAPIKey = SECRET_WRITE_API;

RTCZero rtc; // create RTC object

/* Change these values to set the current initial time */
const byte seconds = 0;
const byte minutes = 28;
const byte hours = 17;

/* Change these values to set the current initial date */
const byte day = 4;
const byte month = 12;
const byte year = 17;

int lightPin = A0; //the analog pin the light sensor is connected to
int tempPin = A1; //the analog pin the TMP36's Vout (sense) pin is connected to
int moisturePin= A2;

// Set this threeshold accordingly to the resistance you used
// The easiest way to calibrate this value is to test the sensor in both dry and wet earth
int threeshold= 800;

bool alert_already_sent=false;
bool email_already_sent=true;
bool already_sent_to_cloud=true;

void setup() {
    Serial.print("Connecting Wifi: ");
    while (WiFi.begin(ssid, password) != WL_CONNECTED) {
  Serial.println("WiFi connected");
  rtc.begin(); // initialize RTC 24H format
  rtc.setTime(hours, minutes, seconds);
  rtc.setDate(day, month, year);
  rtc.setAlarmTime(17, 30, 0);  // Set the time for the Arduino to send the email
  rtc.setAlarmTime(0, 0, 0);    //in this way the request is sent every minute at 0 seconds


void loop() {
  String warning="";
  // Send an extra email only if the plant needs to be waterd
  if(get_average_moisture() < threeshold && !alert_already_sent){
    warning ="Warning your plant needs water !"; // Insert here your emergency message
    warning.replace(" ", "%20");  // replace blank spaces with the URL encoded equivalent
    send_email(get_temperature(), get_average_moisture(),get_light(), warning);
    alert_already_sent=true; // Send the alert only once
  // Send the daily email
  if(rtc.getHours() == 17 && rtc.getMinutes() == 30){
    send_email(get_temperature(), get_average_moisture(),get_light(), warning);
    alert_already_sent = false;
    ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);
    Serial.println("message sent to cloud");

float get_temperature(){
  int reading = analogRead(tempPin); 
  float voltage = reading * 3.3;
  voltage /= 1024.0;
 // Print tempeature in Celsius
 float temperatureC = (voltage - 0.5) * 100 ; //converting from 10 mv per degree wit 500 mV offset

 // Convert to Fahrenheit
 float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0;
 return temperatureF;
int get_average_moisture(){ // make an average of 10 values to be more accurate
  int tempValue=0; // variable to temporarly store moisture value
  for(int a=0; a<10; a++){
  return tempValue/10;
int get_light(){
  int light_value=analogRead(A0);
  return light_value;

void thingspeak_alarm(){

void send_email(float temperature, int moisture, int light, String warning){
  // convert values to String
  String _temperature = String(temperature);
  String _moisture = String(moisture);
  String _light = String(light);
  String _warning = warning;

  if (ZapierClient.connect(host, 443)) {
    ZapierClient.println("POST "+httpsRequest+"temperature="+_temperature+"&moisture="+_moisture+"&light="+_light+"&warning="+_warning+" HTTP/1.1");
    ZapierClient.println("Host: "+ String(host));
    ZapierClient.println("Connection: close");
    while (ZapierClient.available()) { // Print on the console the answer of the server
      char c = ZapierClient.read();
    ZapierClient.stop();  // Disconnect from the server
  else {
    Serial.println("Failed to connect to client");


Remove the "while(!Serial);" line, as this wait for the serial port to be open.


I'm a step before: not able to identify what lipo battery has the right connector to be plugged into a Arduino MKR 1010.

Assuming is the same as Arduino MKR 1000, could someone help me providing the EXACT lipo battery commercial name I can buy on Amazon?

Thanks a lot!


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