reporting battery to domoticZ

Rene046

Hi Awi

Thanks that you want to help,
Im powering it by a lipo battery 1 cell using an dc-dc boost converter to get 5 volts
i would like to see what this lipo is doing during a day. this lipo will be charged by an solar panel 6 volt 300ma still waiting for that panel.

You are absolutely right with my voltage divider it's at 1.9 volt while lipo is at 4.2 volt
I'm not a hero in elektronics , just starting to play with it. so to start i should make an voltage divider that gives me aprox 1,1 volt max at 4,2 volt.
I changed the voltages divider now from 270k-100k
giving me 1.07 volt at 4.2 volt lipo

i'm totally open for any other design you could give, i just used some code from others that was excepted by demoticz.

If you like you could send me an sample how you would do it or change my sketch ..
today i also received my BMP180 and BH1750 i want to include in the future..

Rene046

my serial monitor is now making a bit more cense voltage is about 0,10 volt off
but maybe i do something wrong with calculation.
percentage is still something wrong with

by the way i'm not shure with the low voltage of an 16850 lipo at 3.6 volt ...

20412 MCO:SLP:WUP=-1
22921 TSF:MSG:SEND,2-2-0-0,s=1,c=1,t=0,pt=7,l=5,sg=0,ft=0,st=OK:17.8
T: 17.80
22929 TSF:MSG:SEND,2-2-0-0,s=0,c=1,t=1,pt=7,l=5,sg=0,ft=0,st=OK:35.4
H: 35.40
23939 TSF:MSG:SEND,2-2-0-0,s=4,c=1,t=38,pt=7,l=5,sg=0,ft=0,st=OK:3.53
Battery voltage: 3.53 V
Battery percent: -10 %
23946 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
23954 MCO:SLP:TPD
23955 MCO:SLP:WUP=-1
26465 TSF:MSG:SEND,2-2-0-0,s=0,c=1,t=1,pt=7,l=5,sg=0,ft=0,st=OK:36.1
H: 36.10
27473 TSF:MSG:SEND,2-2-0-0,s=4,c=1,t=38,pt=7,l=5,sg=0,ft=0,st=OK:3.52
Battery voltage: 3.52 V
Battery percent: -12 %
27481 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
27489 MCO:SLP:TPD

and here the latest sketch

// Enable debug prints to serial monitor
#define MY_DEBUG 

// Enable and select radio type attached
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69

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

// Enable debug prints
#define MY_DEBUG

#define CHILD_ID_HUM 0
#define CHILD_ID_TEMP 1
#define HUMIDITY_SENSOR_DIGITAL_PIN 3
#define CHILD_ID_BATTERY 4
unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in milliseconds)

#define SKETCH_NAME "Temp_Hum_Batt"        // Change to a fancy name you like
#define SKETCH_VERSION "2.1"                    // Your version

DHT dht;
float lastTemp;
float lastHum;
boolean metric = true; 
MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
MyMessage msgbatt(CHILD_ID_BATTERY, V_VOLTAGE);

//=========================
// BATTERY VOLTAGE DIVIDER SETUP
// 1M, 470K divider across battery and using internal ADC ref of 1.1V
// Sense point is bypassed with 0.1 uF cap to reduce noise at that point
// ((1e6+470e3)/470e3)*1.1 = Vmax = 3.44 Volts
// 3.44/1023 = Volts per bit = 0.003363075
#define VBAT_PER_BITS 0.0041055718475073313782991202346  // 4.20/1023 volt
#define VMIN 3.6                                  //  Vmin = 3.6 lipo empty
#define VMAX 4.2                                  //  Vmax = 4.2 volt lipo full
int batteryPcnt = 0;                              // Calc value for battery %
int batLoop = 0;                                  // Loop to help calc average
int batArray[3];                                  // Array to store value for average calc.
int BATTERY_SENSE_PIN = A0;                       // select the input pin for the battery sense point
//=========================

void setup()  
{ 
 analogReference(INTERNAL);             // For battery sensing

  delay(500); // Allow time for radio if power used as reset
  
  dht.setup(HUMIDITY_SENSOR_DIGITAL_PIN); 

  metric = getControllerConfig().isMetric;
}

void presentation()  
{ 
  // Send the Sketch Version Information to the Gateway
 // Send the Sketch Version Information to the Gateway
  sendSketchInfo(SKETCH_NAME, SKETCH_VERSION);

  // Register all sensors to gw (they will be created as child devices)
  
  
  present(CHILD_ID_BATTERY, S_MULTIMETER);
  present(CHILD_ID_HUM, S_HUM);
  present(CHILD_ID_TEMP, S_TEMP);
}

void loop()      
{  
  delay(500); // Allow time for radio if power used as reset
  delay(dht.getMinimumSamplingPeriod());
 
  // Fetch temperatures from DHT sensor
  float temperature = dht.getTemperature();
  if (isnan(temperature)) {
      Serial.println("Failed reading temperature from DHT");
  } else if (temperature != lastTemp) {
    lastTemp = temperature;
    if (!metric) {
      temperature = dht.toFahrenheit(temperature);
    }
    send(msgTemp.set(temperature, 1));
    Serial.print("T: ");
    Serial.println(temperature);
  }
  
  // Fetch humidity from DHT sensor
  float humidity = dht.getHumidity();
  if (isnan(humidity)) {
      Serial.println("Failed reading humidity from DHT");
  } else if (humidity != lastHum) {
      lastHum = humidity;
      send(msgHum.set(humidity, 1));
      Serial.print("H: ");
      Serial.println(humidity);
  }
  batM();
  sleep(SLEEP_TIME); //sleep a bit
}

void batM() //The battery calculations
{
   delay(500);
   // Battery monitoring reading
   int sensorValue = analogRead(BATTERY_SENSE_PIN);    
   delay(500);
   
   // Calculate the battery in %
   float Vbat  = sensorValue * VBAT_PER_BITS;
   send(msgbatt.set(Vbat ,2));
   Serial.print("Battery voltage: "); Serial.print(Vbat); Serial.println(" V");  
   int batteryPcnt = static_cast<int>(((Vbat-VMIN)/(VMAX-VMIN))*100.);
   Serial.print("Battery percent: "); Serial.print(batteryPcnt); Serial.println(" %");  
   
   // Add it to array so we get an average of 3 (3x20min)
   batArray[batLoop] = batteryPcnt;
  
   if (batLoop > 2) {  
     batteryPcnt = (batArray[0] + batArray[1] + batArray[2] + batArray[3]);
     batteryPcnt = batteryPcnt / 3;
 
   if (batteryPcnt > 100) {
     batteryPcnt=100;
 }
 
     Serial.print("Battery Average (Send): "); Serial.print(batteryPcnt); Serial.println(" %");
       sendBatteryLevel(batteryPcnt);
       
       batLoop = 0;
      }
     else 
     {
     batLoop++;
     }
}

Rene046

@Rene046 said in reporting battery to domoticZ:

my serial monitor is now making a bit more cense voltage is about 0,10 volt off
but maybe i do something wrong with calculation.
percentage is still something wrong with

im feeding with 3.60 volts at that moment.

AWI

@Rene046 The 1.1V internal reference is not calibrated and can be 10% off, So you need to do some calibration yourself.
(b.t.w. I cleaned your postings a little. Please make sure you use the code markings in the right way, i.e. put them on a new line). To get you going I rewrote the battery routine. Changes:

no real need to average the readings if you give it time to stabilize.
got rid of the "volt per bit" constant
added a "reference value:" for calibration, you can calculate it from the measured voltage and reported voltage.

// battery calculations
void batM(){
	const float vRef = 4.2/ 1.1 ;							// actual value for max reading, adjust with help of measured voltage
	delay(500);
	// Battery monitoring reading
	int sensorValue = analogRead(BATTERY_SENSE_PIN);   		// sensorValue is 0..1023 where 1023 == vRef
	float vBat = sensorValue * vRef / 1024 ;
	send(msgbatt.set(vBat ,2));
	Serial.print("Battery voltage: "); Serial.print(vBat); Serial.println(" V");  
	// Calculate the battery in %
	int batteryPcnt = static_cast<int>(((vBat-VMIN)/(VMAX-VMIN))*100.);
	sendBatteryLevel( batteryPcnt) ;
	Serial.print("Battery percent: "); Serial.print(batteryPcnt); Serial.println(" %");
}

Rene046

Thanks that looks way better.
I just changed
const float vRef = 4.2/ 1.1 ;
into
const float vRef = 4.2/ 1.07 ;
because this is what i measure with my multimeter with 4.2 volt battery and measuring my voltage divider i have 1.07 volt
.
Giving me strange results something must be bad ..... my multimeter ?? it should be closer to 4.2 ? i guess

Battery voltage: 3.92 V
14842 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=0,pt=1,l=1,sg=0,ft=0,st=OK:53
Battery percent: 53 %
14850 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
14856 MCO:SLP:TPD
14858 MCO:SLP:WUP=-1
17367 TSF:MSG:SEND,2-2-0-0,s=1,c=1,t=0,pt=7,l=5,sg=0,ft=0,st=OK:19.4
T: 19.40
17376 TSF:MSG:SEND,2-2-0-0,s=0,c=1,t=1,pt=7,l=5,sg=0,ft=0,st=OK:48.5
H: 48.50
17885 TSF:MSG:SEND,2-2-0-0,s=4,c=1,t=38,pt=7,l=5,sg=0,ft=0,st=OK:3.92
Battery voltage: 3.92 V
17893 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=0,pt=1,l=1,sg=0,ft=0,st=OK:53
Battery percent: 53 %
17900 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
17906 MCO:SLP:TPD```

AWI

@Rene046 You should still compensate for the 1.1 offset. What you should do is calculate the vRef from the measured battery voltage and the real voltage.

Arnold Šlepetis

@Rene046 what resistors do you use to measure battery. VBAT_PER_BITS is not just 4.2/1023. Personally I am using 1m and 300k it gives me up to 4.77V

Rene046

@Arnold-Šlepetis

Hi im using at this moment what i had.
270k-100k giving me 1.07 volt at 4.2 battery

So i stay save , but ok reading is not giving my wanted 4.2 volt but around 3.92 volt

My nano is feeded by an dc -dc boost converter giving me 5 volt from this 4.2 battery.

@AWI
Sorry im still a noob in this, just understood how to make a voltage diver using 3:1 divider
.
Could you please give me a simple example how do this calculation.

Arnold Šlepetis

@Rene046
As I understand correct VBAT_PER_BITS is not just 4.2/1032. This depends what resistors do you use. If you use 1m and 470k VBAT_PER_BITS=0.003363075 made from formula and it will never reads more 3.44v.
#define VMIN and #define VMAX 4.2 used only for formula int batteryPcnt = static_cast<int>(((Vbat-VMIN)/(VMAX-VMIN))*100.);
If you use 270k and 100k maximum is 4.07V so will be VBAT_PER_BITS=0.0039784946236559 and not like in your sketch 0.0041055718475073313782991202346

AWI

@Rene046 You making it complex. The steps)

Make sure that the input voltage is within the range of the reference. You did that with the voltage divider (max 1.07 V) :+1:
set vRefin the sketch to an expected value (4.2 / 1 , where 1 is the calibration value). You did (4.2/1.07) :+1:
Now you need to calibrate in the software:

Measure the battery voltage (batteryVoltage) (not the voltage divider) with the multimeter. You did (4.2 Volt) :+1:
Look at the voltage level reported by the sketch (reportedVoltage). You did (3.92 Volt) :+1:
Calculate the calibration value and adjust vRef. It needs to report 4.2V now it reports 3.92V so you are off by 1.07. => (4.2/1.07) * 1.07 = 4.2 => set vRef to (4.2/ 1.0) and you will be fine.

There are a few reasons why you need to calibrate:

The internal reference of the Arduino (1.1V) is not calibrated (can roughly vary from 1V to 1.2V)
Your voltage divider is not always precise.
Most multimeters are far more accurate...

AWI

@Arnold-Šlepetis Purist physics ;-) : Although you calculation is probably correct for your use case. I associate a VBAT_PER_BITS=0.0039784946236559 with almost atomic precision. As where the internal (band-gap) reference has +- 10% offset and drift with temperature and Vcc (although it is pretty stable for MySensors purposes).
0_1488182473299_upload-573a5ed3-04bf-44df-a0d5-a4b78bb505c5

Rene046

What can i do to get a more stable reading now the voltage goes from 3.80 to 4.20 while feeding with an 4.20 volt

Rene046

@Rene046 said in reporting battery to domoticZ:

What can i do to get a more stable reading now the voltage goes from 3.80 to 4.20 while feeding with an 4.20 volt

It seems like when the nano starts reading the voltage drops a bid.

AWI

@Rene046 Can you be a little more specific? i.e. post a log of voltage readings over time.

Rene046

vref: 4.20 V
sensorValue: 949 bit
219143 TSF:MSG:SEND,2-2-0-0,s=4,c=1,t=38,pt=7,l=5,sg=0,ft=0,st=OK:3.89
Battery voltage: 3.89 V
219151 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=0,pt=1,l=1,sg=0,ft=0,st=OK:48
Battery percent: 48 %
219158 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
219164 MCO:SLP:TPD
219166 MCO:SLP:WUP=-1
221699 TSF:MSG:SEND,2-2-0-0,s=0,c=1,t=1,pt=7,l=5,sg=0,ft=0,st=OK:35.2
H: 35.20
vref: 4.20 V
sensorValue: 951 bit
222708 TSF:MSG:SEND,2-2-0-0,s=4,c=1,t=38,pt=7,l=5,sg=0,ft=0,st=OK:3.90
Battery voltage: 3.90 V
222717 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=0,pt=1,l=1,sg=0,ft=0,st=OK:50
Battery percent: 50 %
222724 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
222731 MCO:SLP:TPD
222733 MCO:SLP:WUP=-1
225242 TSF:MSG:SEND,2-2-0-0,s=1,c=1,t=0,pt=7,l=5,sg=0,ft=0,st=OK:20.6
T: 20.60
225251 TSF:MSG:SEND,2-2-0-0,s=0,c=1,t=1,pt=7,l=5,sg=0,ft=0,st=OK:34.5
H: 34.50
vref: 4.20 V
sensorValue: 955 bit
226260 TSF:MSG:SEND,2-2-0-0,s=4,c=1,t=38,pt=7,l=5,sg=0,ft=0,st=OK:3.92
Battery voltage: 3.92 V
226269 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=0,pt=1,l=1,sg=0,ft=0,st=OK:52
Battery percent: 52 %
226276 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
226282 MCO:SLP:TPD

AWI

@Rene046 From your earlier postings I can see that you are using a boost converter. Speaking in general these things make a lot of noise on the power line and are certainly not a stable supply.
Just a few considerations:

A nano is not well suited for battery operation. These tend to dissipate at minimum 5mA and will drown a one cell battery fast. Go for a 3.3V pro-mini and remove the led.
Get rid of the Boost converter and power directly from the battery. The radio and pro-mini will work fine on 3.6V using a regulator (LDO). In this case you can measure battery directly from the Vcc pin without divider.

Rene046

Last reading from multimeter battery voltage 4.204 volt now i measure A0 1,104 > gnd

AWI

@Rene046 What is the output of the DC=DC converter measuring? Are you powering the nano on the Vcc or Vin pin?

Rene046

Hi Awi i will build someday if i got it working this project on a pro-mini,.
im not measuring the voltage on the dc-dc booster but on the battery side feeding the converter.
I need this booster because i also feeding my DHT with 5 volt and in future other sensors.BH1750, BMP180, Soil moisture sensor
and im charging my battery in the future with an 6 volt solar panel.
So to see this is working during day time i should be able to read the charging voltage of 4.2 volt and during the night the voltage of battery dropping

Rene046

@AWI

Im feeding the 5v pin with 5.14 volt coming from the dc-dc output not the vin

reporting battery to domoticZ

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