My 2AA battery sensor

Patrick Mcgillan

Good info here. Thought comes to mind about using a small solar cell off a defectivet walkway light to add a little charge back in to the system, when there is any kind of light around.

m26872

Just an update on my battery levels. My VeraLite Datamine-plugin won't longer plot for me. I suspect I'm out of VeraLite memory to handle all the data. This is it. (Look above for last graphs.)
Node 16: BatteryLevel 51
Node 101: Dead 03 Feb
Node 110; BatteryLevel 57
Node 105: BatteryLevel 80
Node 106: BatteryLevel 53
As I hoped, the decrease rate for 105 and 106 is now less than 5% per month and 6-month target is already passed by half.
The revenge of the Chinese step-up ?!

m26872

Someone else noticed that one of the two batteries drained by the step-up always has negative(!) charge? Due to the AC-load? Could it be possible to extend battery life by adding some kind of capacitor?

m26872

Node 105 and 106 down just 1% since last post (22 days ago). Not bad. Relatively stable readings and low activity, but it doesn't matter since we're all expected the sleep mode consumption to be the worst.

? Offline

@EasyIoT: Thank you for your nice descriptions of the low power sensors.
I have some questions regarding the temperature sensor:
Did you use a "Low power modified" Arduino for that as well?
How are you able to power the sensor via the step-up only when needed? Do you power the step-up via an digital pin or something?

@m26872: Also thanks for your design. I am thinking of building something similar. So you got now about 5% battery drop per month using the china stepup with desoldered LED?

m26872

@daenny said:

So you got now about 5% battery drop per month using the china stepup with desoldered LED?

Today I read Node 105: 78% and Node 106: 51%. That's only 2% in the last 38 days.

Edit: Perhaps using the "%" here is a little careless, but I think everyone knows that we're talking battery level.

EasyIoT

@daenny yes, I'm using DO pin and MOSFET connected to step up regulator. But this is complicated solution. I'ts better to use different temperature sensor which can operate down to 1.8V. Right now I'm testing custom board with NRF24L and HTU21D (it's not cheap, but it can work down to 1,8V). Results are pretty good. Temperature and humidity sensor can operate more than 5 years on 2 AA batteries. For example door window sensor and water leak sensor can work more than 10 years on 2 AA batteries. It's seems that for those sensors AA batteries are overkill.

funky81

@m26872 I still dont get it. Why I cant get the same efficient power like you.
I already follow all of your requirement in the first thread - difference only I use breadboard.
The minimum consumption (sleep) that I've got still 2.4mA, compare to you, it still huge differences. I dont know what's wrong with my setup.

My sketch wake up every 10s (consumption up to 3.5mA), while sleep the lowest is 2.4mA.

#include <avr/sleep.h>    // Sleep Modes
#include <MySensor.h>
#include <SPI.h>

MySensor gw;
#define BATTERY_SENSE_PIN 
#define SLEEP_IN_MS 86400000 // 1 day
#define PROD false

int oldBatLevel;

void setup()
{
  gw.begin(NULL,1);
  gw.sendSketchInfo("Basic-Sketch-MySensor", "1.0");


  pinMode(2,INPUT);
  digitalWrite (2, LOW);

  pinMode(3,INPUT);
  digitalWrite (3, LOW);

  pinMode(4,OUTPUT);
  digitalWrite (4, LOW);

  pinMode(5,INPUT);
  digitalWrite (5, LOW);

  pinMode(6,INPUT);
  digitalWrite (6, LOW);

  pinMode(7,INPUT);
  digitalWrite (7, LOW);

  pinMode(8,INPUT);
  digitalWrite (8, LOW);
  
  oldBatLevel = -1; 

  sendValue();
  Serial.println("Startup Finished");
  TurnOnLed();
}

void TurnOnLed(){

    digitalWrite(4,HIGH);
 gw.sleep(1000);
        digitalWrite(4,LOW);
  
  gw.sleep(100);
}

void loop ()
{  
  sendValue();
  gw.sleep(1000*10);
}  // end of loop

void sendValue()
{
  gw.powerUp(); 

  int batLevel = getBatteryLevel();
  if (!PROD){
    gw.sendBatteryLevel(batLevel);  
    TurnOnLed();
  }
  else{
    if (oldBatLevel != batLevel)
    {
      gw.sendBatteryLevel(batLevel);   
      oldBatLevel = batLevel;
      TurnOnLed();
    }
  }

  gw.powerDown(); 
}

// Battery measure
int getBatteryLevel ()
{
  int results = (readVcc() - 2000)  / 10;  

  if (results > 100)
    results = 100;
  if (results < 0)
    results = 0;
  return results;
} // end of getBandgap

// when ADC completed, take an interrupt
EMPTY_INTERRUPT (ADC_vect);

long readVcc() {
  long result;
  // Read 1.1V reference against AVcc
  ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
  delay(2); // Wait for Vref to settle
  noInterrupts ();
  // start the conversion
  ADCSRA |= _BV (ADSC) | _BV (ADIE);
  set_sleep_mode (SLEEP_MODE_ADC);    // sleep during sample
  interrupts ();
  sleep_mode ();
  // reading should be done, but better make sure
  // maybe the timer interrupt fired
  while (bit_is_set(ADCSRA,ADSC));
  result = ADCL;
  result |= ADCH<<8;
  result = 1126400L / result; // Back-calculate AVcc in mV

  return result;
}```

m26872

@funky81 said:

@m26872 I still dont get it. Why I cant get the same efficient power like you....

I see that your sketch uses the internal battery monitoring method. That isn't possible when using the design as in this threads subject, with a step-up regulator that makes Vbat different from Vcc. Are you sure you're not confusing my design with EaysIoTs ?

Anyhow, I can't explain the sleep mode consumption, it seems like something isn't sleeping like it should.

Here's my sketch for Node 105/106:

// Egen kombo-nod för DHT22, BMP180 och batterimonitering.
// 20141019
// DHT-22 Working voltage: DC 3.3-5.5V (so connect after step-up regulator). http://www.adafruit.com/datasheets/Digital%20humidity%20and%20temperature%20sensor%20AM2302.pdf
// BMP180 (compatible with BMP085) working voltage 1.8-3.6V. Different boards with different power and pullups. Datasheet for ic only: http://www.adafruit.com/datasheets/BST-BMP180-DS000-09.pdf 
#include <SPI.h>
#include <MySensor.h>  
#include <DHT.h>
#include <Wire.h>
#include <Adafruit_BMP085.h> // N.b. The new library includes the function readSealevelPressure() 

#define NODE_ID 106  // Manually asign Node Id  <<<<<<<<<<<<<<<<<<<  ENTER THIS !!!!
#define ONE_WIRE_BUS 3 // Pin where dallase sensor bus is connected. <<<<<<<<<<<<<<<  DON'T FORGET 4k7 PULL-UP !!! >>>>>>>>>>>>>>>>
#define VBAT_PER_BITS 0.003363075  // Calculated volts per bit from the used battery montoring voltage divider.   Internal_ref=1.1V, res=10bit=2^10-1=1023, Eg for 3V (2AA): Vin/Vb=R1/(R1+R2)=470e3/(1e6+470e3),  Vlim=Vb/Vin*1.1=3.44V, Volts per bit = Vlim/1023= 0.003363075
#define VMIN 1.9  // Battery monitor lower level. Vmin_radio=1.9V
#define VMAX 3.3  //  " " " high level. Vmin<Vmax<=3.44
#define CHILD_ID_HUM 0
#define CHILD_ID_TEMP 1
#define BARO_CHILD 2
//#define TEMP_CHILD 3  // Commented since don't need the Bmp tempsensor
#define HUMIDITY_SENSOR_DIGITAL_PIN 3  // <<<<<<<<<<<<<<<<<<<<<<<<  Use 4k7 Pull-up. MySensors webpage doesn't use, datasheet does. Adafruit does https://learn.adafruit.com/dht/using-a-dhtxx-sensor

unsigned long SLEEP_TIME = 15*60000; //  sleep time between reads (in milliseconds)
unsigned long preSleepTime = 5*60000; //  sleep time for extra pre hum-reading for simple avaraging filter
Adafruit_BMP085 bmp = Adafruit_BMP085();      // Digital Pressure Sensor 
MySensor gw;
DHT dht;
float lastTemp;
float lastHum;
float lastPressure = -1;
//float lastBmpTemp = -1; // Commented since don't need the Bmp tempsensor
MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
//MyMessage tempMsg(TEMP_CHILD, V_TEMP); // Commented since don't need the Bmp tempsensor
MyMessage pressureMsg(BARO_CHILD, V_PRESSURE);
int BATTERY_SENSE_PIN = A0;  // select the input pin for the battery sense point
int oldBatteryPcnt = 0;

void setup()  
{ 
  analogReference(INTERNAL);    // use the 1.1 V internal reference for battery level measuring
  delay(500); // Allow time for radio if power used as reset <<<<<<<<<<<<<< Experimented with good result 
  gw.begin(NULL,NODE_ID); // Startup and initialize MySensors library. Set callback for incoming messages. 
  dht.setup(HUMIDITY_SENSOR_DIGITAL_PIN); 

  gw.sendSketchInfo("EgHumBarTemBatv2", "2.0 20141110");   // Send the Sketch Version Information to the Gateway
  
  if (!bmp.begin()) {
	Serial.println("Could not find a valid BMP085 sensor, check wiring!");
	while (1) {  }
  }

  gw.present(CHILD_ID_HUM, S_HUM);   // Register all sensors to gw (they will be created as child devices)
  gw.present(CHILD_ID_TEMP, S_TEMP);
  gw.present(BARO_CHILD, S_BARO);
//  gw.present(TEMP_CHILD, S_TEMP); // Commented since don't need the Bmp tempsensor
  
}

void loop()      
{  
  delay(dht.getMinimumSamplingPeriod());
  
  float humidity_1 = dht.getHumidity();
  if (isnan(humidity_1)) {
	  Serial.println("Failed reading humidity_1 from DHT");
  } 
//  else {
//      Serial.print("Hum1: ");
//      Serial.println(humidity_1);
//  }  
  
  gw.sleep(preSleepTime); //sleep shortly until the "real" processing happens
  
  delay(dht.getMinimumSamplingPeriod());

  float humidity_2 = dht.getHumidity();
  if (isnan(humidity_2)) {
	  Serial.println("Failed reading humidity_2 from DHT");
  } 
//  else {
//      Serial.print("Hum2: ");
//      Serial.println(humidity_2);
//  }
  if ( isnan(humidity_1) && isnan(humidity_2) ) {
	Serial.println("Failed reading humidity_1 and humidity_2 from DHT");
  }
  else if ( isnan(humidity_2) && !isnan(humidity_1) ) { // && abs(humidity_1-lastHum)>2. ) {  // Ev hysteres
	gw.send(msgHum.set(humidity_1, 1));
	lastHum = humidity_1;
//    Serial.println("Humidity_1 sent to gw.");
  } 
  else if ( isnan(humidity_1) && !isnan(humidity_2) ) { // && abs(humidity_2-lastHum)>2. ) {
	gw.send(msgHum.set(humidity_2, 1));
	lastHum = humidity_2;
//    Serial.println("Humidity_2 sent to gw.");
  }  
  else {
//    Serial.println("Else mean calc");
	float humidity_m = (humidity_1+humidity_2)/2. ;  // Averageing the two.
//    if ( abs(humidity_m-lastHum) > 2. ) {  
	  gw.send(msgHum.set(humidity_m, 1));
	  lastHum = humidity_m;
//      Serial.println("The mean humidity_m sent to gw.");
//    }
  }

  float temperature = dht.getTemperature();
  if (isnan(temperature)) {
	  Serial.println("Failed reading temperature from DHT");
  } else if (temperature != lastTemp) {
	lastTemp = temperature;
	gw.send(msgTemp.set(temperature, 1));  // Always send temperature
//      Serial.print("Sent temp: ");
//      Serial.println(temperature);
  }

  float pressure = bmp.readPressure()/100;
//  float pressureS = bmp.readSealevelPressure(75.)/100;
//  Serial.print("Pressure = "); Serial.print(pressure); Serial.println(" Pa");
//  Serial.print("SeaLevelPressure = "); Serial.print(pressureS); Serial.println(" Pa");
  if (pressure != lastPressure) {
	gw.send(pressureMsg.set(pressure, 0));
	lastPressure = pressure;
//    Serial.print("Sent pressure: ");
//    Serial.println(pressure);
  }
//  float bmpTemperature = bmp.readTemperature(); // Commented since don't need the Bmp tempsensor
////  Serial.print("Temperature = "); Serial.print(bmpTemperature); Serial.println(" *C");
//  if (bmpTemperature != lastBmpTemp) {
//    gw.send(tempMsg.set(bmpTemperature,1));
//    lastBmpTemp = bmpTemperature;
//  }

  int sensorValue = analogRead(BATTERY_SENSE_PIN);    // Battery monitoring reading
//  Serial.println(sensorValue);
  float Vbat  = sensorValue * VBAT_PER_BITS;
//  Serial.print("Battery Voltage: "); Serial.print(Vbat); Serial.println(" V");
 //int batteryPcnt = sensorValue / 10;
  int batteryPcnt = static_cast<int>(((Vbat-VMIN)/(VMAX-VMIN))*100.);   
//  Serial.print("Battery percent: "); Serial.print(batteryPcnt); Serial.println(" %");
  if (oldBatteryPcnt != batteryPcnt) {
	gw.sendBatteryLevel(batteryPcnt);
	oldBatteryPcnt = batteryPcnt;
  }

  gw.sleep(SLEEP_TIME); //sleep a bit
}

funky81

@m26872 in my previous sketch, yes, i'm trying to use EasyIOT's (Thanks @EasyIoT :+1: )
anyway, i'll flash with yours. I'll let know the result

m26872

I declare the 6 months criteria easily passed. And the chinese step up regulator to be good value for money. Next target; 12 months.

sundberg84

Hi!
This is also what im trying to do... have the same components/material as you and added the resistors for battery measurement. I dont get this long life (sleeps 15min, activated and sends).

Can you post some sort of schematics or more detailed pictures so i can see your connections?
Would be great!
Here is my own try for a schematics:
http://forum.mysensors.org/uploads/upload-5ed3f6ed-2d8c-4e6e-83bf-407973550c49.jpg

Sweebee

A tip for much better batterylife: burn a new bootloader for 1mhz. Now you can attach the arduino and nrf directly to the batteries and you can measure the battery with the Internal voltage meter of the 328p. If you use a dht you attach the step-up conv. And only attach the dht to it.

m26872

@sundberg84
I've looked at your lovely drawing before and I don't see anything wrong with it except from that 0.1uF capacitor should be in parallell just with the 470k resistor, but it shouldn't matter regarding battery life time. What would be more interesting is to see your sketch. Or do you use the same as I do?

A schematic and a few better pictures is on my to do list, but will probably come sooner now since you asked for it.

sundberg84

@m26872
Pretty much the same, i have stolen majority of your code:
Ive a array to get an average battery value each hour:

#include <SPI.h>
#include <MySensor.h>  
#include <DHT.h>  

//ställ in varje gång!=========================
#define SketchName "Sovrum Uppe"
#define SketchVer "1.0"
#define NodeID 2
#define VBAT_PER_BITS 0.003363075  // Calculated volts per bit from the used battery montoring voltage divider.   Internal_ref=1.1V, res=10bit=2^10-1=1023, Eg for 3V (2AA): Vin/Vb=R1/(R1+R2)=470e3/(1e6+470e3),  Vlim=Vb/Vin*1.1=3.44V, Volts per bit = Vlim/1023= 0.003363075
#define VMIN 1.9  // Battery monitor lower level. Vmin_radio=1.9V
#define VMAX 3.3  //  " " " high level. Vmin<Vmax<=3.44
#define CHILD_ID_HUM 0
#define CHILD_ID_TEMP 1
#define HUMIDITY_SENSOR_DIGITAL_PIN 3
int BATTERY_SENSE_PIN = A0;  // select the input pin for the battery sense point
unsigned long SLEEP_TIME = 15*60000;
//unsigned long SLEEP_TIME = 5000; //debug
//Ställ även in gw.begin(,,,)
//ställ in varje gång!=========================

float lastTemp;
float lastHum;
boolean metric = true; 
int batteryPcnt = 0;
int batLoop = 0;
int batArray[3];

MySensor gw;
DHT dht;

MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);

void setup()  
{ 
// use the 1.1 V internal reference
  analogReference(INTERNAL);
  delay(500); // Allow time for radio if power used as reset <<<<<<<<<<<<<< Experimented with good result 
   
  gw.begin(NULL, NodeID, false);
//incomingMessageCallback - Callback function for incoming messages from other nodes or controller and request responses. Default is NULL.
//nodeId - The unique id (1-254) for this sensor. Default is AUTO(255) which means sensor tries to fetch an id from controller.
//repeaterMode - Activate repeater mode. This node will forward messages to other nodes in the radio network. Make sure to call process() regularly. Default in false
  
  dht.setup(HUMIDITY_SENSOR_DIGITAL_PIN); 

  // Send the Sketch Version Information to the Gateway
  gw.sendSketchInfo(SketchName, SketchVer);

  // Register all sensors to gw (they will be created as child devices)
  gw.present(CHILD_ID_HUM, S_HUM);
  gw.present(CHILD_ID_TEMP, S_TEMP);
  
  metric = gw.getConfig().isMetric;
}

void loop()      
{  
  int sensorValue = analogRead(BATTERY_SENSE_PIN);    // Battery monitoring reading
delay(1000);
  delay(dht.getMinimumSamplingPeriod());

 
  float temperature = dht.getTemperature();
  Serial.print("Temp: "); Serial.print(temperature); Serial.println(" C");
  
 if (temperature > 0) {
   gw.send(msgTemp.set(temperature, 1));
  }
 
delay(1000);
 
  float humidity = dht.getHumidity();
  Serial.print("Hum: "); Serial.print(humidity); Serial.println(" %");
   
   if (humidity > 0) {
    gw.send(msgHum.set(humidity, 1));
}

delay(1000);
   
   float Vbat  = sensorValue * VBAT_PER_BITS;
   int batteryPcnt = static_cast<int>(((Vbat-VMIN)/(VMAX-VMIN))*100.);   
 Serial.print("Battery percent: "); Serial.print(batteryPcnt); Serial.println(" %");  
   batArray[batLoop] = batteryPcnt;
  
   if (batLoop > 2) {
     
     batteryPcnt = (batArray[0] + batArray[1] + batArray[2] + batArray[3]);
     batteryPcnt = batteryPcnt / 4;
    Serial.print("Battery percent (Avg (4):) "); Serial.print(batteryPcnt); Serial.println(" %");

       gw.sendBatteryLevel(batteryPcnt);
       batLoop = 0;   
     }
     else 
     {
     batLoop = batLoop + 1;
     }
   
  gw.sleep(SLEEP_TIME); //sleep a bit
}

m26872

@Sweebee
It's already been discussed earlier in this thread (see EasyIoTs posts above), it's nevertheless a very good tip. I also have some test nodes running, but I consider it to be the next step from the "basic" design which was this threads concept. If I'll post something with this low-power-tweaked design it'll therefore be in a new thread. I should probably write something about this as an update in the first post...

m26872

@sundberg84
I'm no code expert, and the only thing I can think of is that your "delay(1000)" will keep the power hungry radio awake. If you need delays (apart from debug) I'd prefer sleep instead. What's your battery life time look like?

m26872

UPDATE
I've updated the first post with

A wiring layout.
Added a text about the low-power option
A few minor details.

sundberg84

Great layout/way to show your project - really nice!

Its exactly as I do it so im getting a bit jealus here... . One node is down after a week.
It might be the hardware or me not so good soldering so i short something out.

I will try some more nodes now you have comfirmed I do it the right way and that should work.

@m26872
Thank you!

m26872

@sundberg84
Thx, good you liked it.
With such fast battery drain it should be easier to trace the current draw. First you'll need to measure the current. Second option is of course the good old switch-and-replace troubleshooting method.
I've read about hardware and quality issues, but let's hope it isn't...

My 2AA battery sensor

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