💬 Battery Powered Sensors

mfalkvidd

@Nicklas-Starkel great that you figured out what was wrong

bjacobt

Hi, I built this circuit and arduino reads 1.11 V or 33%. I've new batteries and multimeter reads 3.10 volts. Do you know what could be wrong? I'm using 1M and 470k resistors on pin A0.

tonnerre33

Hello,

Did you put this command in the setup sketch ?

analogReference(INTERNAL);

bjacobt

@tonnerre33, yes I've analogReference(INTERNAL); in setup()

tonnerre33

It's normal to have 1.1V on A0 when you have 3.3V on your batteries.

Where did you get the 1.11V value ? In the serial print or with your multimeter ?
If you read the value with the serial print, which variable is it (sensorValue or batteryV) ?

bjacobt

@tonnerre33 in the serial print and MySensor MQTT gateway

bjacobt

@tonnerre33, I'm trying to build arduio that can run on 2 AA batteries. I'm using MySensors for library and building arduino circuit based on this https://openhomeautomation.net/arduino-battery/

tonnerre33

Can you post the logs of your node and the skech used ?

mfalkvidd

@bjacobt https://www.mysensors.org/build/battery#measuring-and-reporting-battery-level describes how the battery voltage is calculated and the example sketch has code for doing the calculation. Looks like you've missed reading this part:

   // 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
...
float batteryV  = sensorValue * 0.003363075;

bjacobt

@tonnerre33
Here are the logs from Arduino Serial console

Starting sensor (RNNNA-, 2.0.0)
TSM:INIT
TSM:RADIO:OK
TSP:ASSIGNID:OK (ID=101)
TSM:FPAR
TSP:MSG:SEND 101-101-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=bc:
TSP:MSG:READ 0-0-101 s=255,c=3,t=8,pt=1,l=1,sg=0:0
TSP:MSG:FPAR RES (ID=0, dist=0)
TSP:MSG:PAR OK (ID=0, dist=1)
TSM:FPAR:OK
TSM:ID
TSM:CHKID:OK (ID=101)
TSM:UPL
TSP:PING:SEND (dest=0)
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=ok:1
TSP:MSG:READ 0-0-101 s=255,c=3,t=25,pt=1,l=1,sg=0:1
TSP:MSG:PONG RECV (hops=1)
TSP:CHKUPL:OK
TSM:UPL:OK
TSM:READY
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=ok:0100
!TSP:MSG:SEND 101-101-0-0 s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=fail:2.0.0
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=6,pt=1,l=1,sg=0,ft=1,st=ok:0
TSP:MSG:READ 0-0-101 s=255,c=3,t=15,pt=6,l=2,sg=0:0100
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=11,pt=0,l=13,sg=0,ft=0,st=ok:Battery Meter
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=ok:1.0
Request registration...
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=ok:2
TSP:MSG:READ 0-0-101 s=255,c=3,t=27,pt=1,l=1,sg=0:1
Node registration=1
Init complete, id=101, parent=0, distance=1, registration=1
330
Battery Voltage: 1.11 V
Battery percent: 33 %
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=0,pt=1,l=1,sg=0,ft=0,st=ok:33

The sketch used is this:

/**
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * DESCRIPTION
 *
 * This is an example that demonstrates how to report the battery level for a sensor
 * Instructions for measuring battery capacity on A0 are available here:
 * http://www.mysensors.org/build/battery
 * 
 */


#define MY_NODE_ID  101

// Enable debug prints to serial monitor
#define MY_DEBUG 

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

#include <MySensors.h>



int BATTERY_SENSE_PIN = A0;  // select the input pin for the battery sense point

unsigned long SLEEP_TIME = 100000;  // sleep time between reads (seconds * 1000 milliseconds)
int oldBatteryPcnt = 0;

void setup()  
{
   // use the 1.1 V internal reference
#if defined(__AVR_ATmega2560__)
   analogReference(INTERNAL1V1);
#else
   analogReference(INTERNAL);
#endif
}

void presentation() {
   // Send the sketch version information to the gateway and Controller
   sendSketchInfo("Battery Meter", "1.0");
}

void loop()
{
   // get the battery Voltage
   int sensorValue = analogRead(BATTERY_SENSE_PIN);
   #ifdef MY_DEBUG
   Serial.println(sensorValue);
   #endif

   // 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

   int batteryPcnt = sensorValue / 10;

   #ifdef MY_DEBUG
   float batteryV  = sensorValue * 0.003363075;
   Serial.print("Battery Voltage: ");
   Serial.print(batteryV);
   Serial.println(" V");

   Serial.print("Battery percent: ");
   Serial.print(batteryPcnt);
   Serial.println(" %");
   #endif

   if (oldBatteryPcnt != batteryPcnt) {
     // Power up radio after sleep
     sendBatteryLevel(batteryPcnt);
     oldBatteryPcnt = batteryPcnt;
   }
   sleep(SLEEP_TIME);
}```

What I see on the gateway is:

mysGateway: TSF:MSG:READ,101-101-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysGateway: TSF:MSG:BC
mysGateway: TSF:MSG:FPAR REQ,ID=101
mysGateway: TSF:PNG:SEND,TO=0
mysGateway: TSF:CKU:OK
mysGateway: TSF:MSG:GWL OK
mysGateway: TSF:MSG:SEND,0-0-101-101,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=24,pt=1,l=1,sg=0:1
mysGateway: TSF:MSG:PINGED,ID=101,HP=1
mysGateway: TSF:MSG:SEND,0-0-101-101,s=255,c=3,t=25,pt=1,l=1,sg=0,ft=0,st=OK:1
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=15,pt=6,l=2,sg=0:0100
mysGateway: !TSF:MSG:SEND,0-0-101-101,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=NACK:0100
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=6,pt=1,l=1,sg=0:0
mysGateway: Sending message on topic: mysensors-out/101/255/3/0/6
mysGateway: TSF:MSG:READ,101-101-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
mysGateway: TSF:MSG:BC
mysGateway: TSF:MSG:FPAR REQ,ID=101
mysGateway: TSF:CKU:OK,FCTRL
mysGateway: TSF:MSG:GWL OK
mysGateway: TSF:MSG:SEND,0-0-101-101,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=24,pt=1,l=1,sg=0:1
mysGateway: TSF:MSG:PINGED,ID=101,HP=1
mysGateway: TSF:MSG:SEND,0-0-101-101,s=255,c=3,t=25,pt=1,l=1,sg=0,ft=0,st=OK:1
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=15,pt=6,l=2,sg=0:0100
mysGateway: !TSF:MSG:SEND,0-0-101-101,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=NACK:0100
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=6,pt=1,l=1,sg=0:0
mysGateway: Sending message on topic: mysensors-out/101/255/3/0/6
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=11,pt=0,l=13,sg=0:Battery Meter
mysGateway: Sending message on topic: mysensors-out/101/255/3/0/11
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=12,pt=0,l=3,sg=0:1.0
mysGateway: Sending message on topic: mysensors-out/101/255/3/0/12
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=26,pt=1,l=1,sg=0:2
mysGateway: TSF:MSG:SEND,0-0-101-101,s=255,c=3,t=27,pt=1,l=1,sg=0,ft=0,st=OK:1
mysGateway: TSF:MSG:READ,101-101-0,s=255,c=3,t=0,pt=1,l=1,sg=0:33
mysGateway: Sending message on topic: mysensors-out/101/255/3/0/0```

Thank for your help!
Jacob

bjacobt

hi @mfalkvidd,

Do you mind clarifying a bit, I've done sensorValue * 0.003363075

analogRead(BATTERY_SENSE_PIN);

Gives me 330, so
330 * 0.003363075 = 1.10981475 volts

Thank You!
Jacob

mfalkvidd

@bjacobt hmm. Yes, you are correct. The calculation seem a bit strange.
Using this calculator I entered
output 1.10981475 V
R1 1000000
R2 470000
Which gives a battery voltage of 3.471V

Looks like the calculations in the sketch are wrong? Or at least confusing :) I'm pretty lost.

tonnerre33

analogRead(BATTERY_SENSE_PIN);

must give you 1023 and not 330.
For me it's a problem of value resistance or analogReference.

Try to add this

analogReference(INTERNAL);
sensorValue = analogRead(BATTERY_SENSE_PIN);
  #ifdef MY_DEBUG
 Serial.print("Value A0 before force reference: ");
 Serial.print(sensorValue);
#endif
delay(10000);
sensorValue = analogRead(BATTERY_SENSE_PIN);
  #ifdef MY_DEBUG
 Serial.print("Value A0 after force reference: ");
 Serial.print(sensorValue);
#endif

Just after this existing code :

   #ifdef MY_DEBUG
   Serial.println(sensorValue);
   #endif

And plz send me the logs of the node ;)

bjacobt

@tonnerre33 Its still the same

Starting sensor (RNNNA-, 2.0.0)
TSM:INIT
TSM:RADIO:OK
TSP:ASSIGNID:OK (ID=101)
TSM:FPAR
TSP:MSG:SEND 101-101-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=bc:
TSP:MSG:READ 0-0-101 s=255,c=3,t=8,pt=1,l=1,sg=0:0
TSP:MSG:FPAR RES (ID=0, dist=0)
TSP:MSG:PAR OK (ID=0, dist=1)
TSM:FPAR:OK
TSM:ID
TSM:CHKID:OK (ID=101)
TSM:UPL
TSP:PING:SEND (dest=0)
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=ok:1
TSP:MSG:READ 0-0-101 s=255,c=3,t=25,pt=1,l=1,sg=0:1
TSP:MSG:PONG RECV (hops=1)
TSP:CHKUPL:OK
TSM:UPL:OK
TSM:READY
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=ok:0100
TSP:MSG:SEND 101-101-0-0 s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=ok:2.0.0
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=6,pt=1,l=1,sg=0,ft=0,st=ok:0
TSP:MSG:READ 0-0-101 s=255,c=3,t=15,pt=6,l=2,sg=0:0100
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=11,pt=0,l=13,sg=0,ft=0,st=ok:Battery Meter
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=ok:1.0
Request registration...
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=ok:2
TSP:MSG:READ 0-0-101 s=255,c=3,t=27,pt=1,l=1,sg=0:1
Node registration=1
Init complete, id=101, parent=0, distance=1, registration=1
330
Value A0 before force reference: 327
Value A0 after force reference: 329
Battery Voltage: 1.11 V
Battery percent: 32 %
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=0,pt=1,l=1,sg=0,ft=0,st=ok:32

/**
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * DESCRIPTION
 *
 * This is an example that demonstrates how to report the battery level for a sensor
 * Instructions for measuring battery capacity on A0 are available here:
 * http://www.mysensors.org/build/battery
 * 
 */


#define MY_NODE_ID  101

// Enable debug prints to serial monitor
#define MY_DEBUG 

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

#include <MySensors.h>



int BATTERY_SENSE_PIN = A0;  // select the input pin for the battery sense point

unsigned long SLEEP_TIME = 100000;  // sleep time between reads (seconds * 1000 milliseconds)
int oldBatteryPcnt = 0;

void setup()  
{
   // use the 1.1 V internal reference
#if defined(__AVR_ATmega2560__)
   analogReference(INTERNAL1V1);
#else
   analogReference(INTERNAL);
#endif
}

void presentation() {
   // Send the sketch version information to the gateway and Controller
   sendSketchInfo("Battery Meter", "1.0");
}

void loop()
{
   // get the battery Voltage
   int sensorValue = analogRead(BATTERY_SENSE_PIN);
   #ifdef MY_DEBUG
   Serial.println(sensorValue);
   #endif

analogReference(INTERNAL);
sensorValue = analogRead(BATTERY_SENSE_PIN);
  #ifdef MY_DEBUG
 Serial.print("Value A0 before force reference: ");
 Serial.println(sensorValue);
#endif
delay(10000);
sensorValue = analogRead(BATTERY_SENSE_PIN);
  #ifdef MY_DEBUG
 Serial.print("Value A0 after force reference: ");
 Serial.println(sensorValue);
#endif
   

   // 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

   int batteryPcnt = sensorValue / 10;

   #ifdef MY_DEBUG
   float batteryV  = sensorValue * 0.003363075;
   Serial.print("Battery Voltage: ");
   Serial.print(batteryV);
   Serial.println(" V");

   Serial.print("Battery percent: ");
   Serial.print(batteryPcnt);
   Serial.println(" %");
   #endif

   if (oldBatteryPcnt != batteryPcnt) {
     // Power up radio after sleep
     sendBatteryLevel(batteryPcnt);
     oldBatteryPcnt = batteryPcnt;
   }
   sleep(SLEEP_TIME);
}```

tonnerre33

Ok it's not a problem with the analogReference, you can delete this part of code.
Did you control your resistance value and did you do this schema ?
alt text

bjacobt

Hi,
I'm sorry what do you mean by "control your resistance value"

this is my circuit,

1M resistor to +V rail, 470K resistor to GND and middle point to A0.

,

tonnerre33

Ok try to remove the jumper between V+ and AREF

bjacobt

@tonnerre33 That was it!

I'm getting Battery Voltage: 3.10 V
Battery percent: 92 %

Thank you so much :)

Starting sensor (RNNNA-, 2.0.0)
TSM:INIT
TSM:RADIO:OK
TSP:ASSIGNID:OK (ID=101)
TSM:FPAR
TSP:MSG:SEND 101-101-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=bc:
TSP:MSG:READ 0-0-101 s=255,c=3,t=8,pt=1,l=1,sg=0:0
TSP:MSG:FPAR RES (ID=0, dist=0)
TSP:MSG:PAR OK (ID=0, dist=1)
TSM:FPAR:OK
TSM:ID
TSM:CHKID:OK (ID=101)
TSM:UPL
TSP:PING:SEND (dest=0)
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=ok:1
TSP:MSG:READ 0-0-101 s=255,c=3,t=25,pt=1,l=1,sg=0:1
TSP:MSG:PONG RECV (hops=1)
TSP:CHKUPL:OK
TSM:UPL:OK
TSM:READY
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=ok:0100
!TSP:MSG:SEND 101-101-0-0 s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=fail:2.0.0
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=6,pt=1,l=1,sg=0,ft=1,st=ok:0
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=11,pt=0,l=13,sg=0,ft=0,st=ok:Battery Meter
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=ok:1.0
Request registration...
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=ok:2
TSP:MSG:READ 0-0-101 s=255,c=3,t=27,pt=1,l=1,sg=0:1
Node registration=1
Init complete, id=101, parent=0, distance=1, registration=1
922
Value A0 before force reference: 924
Value A0 after force reference: 923
Battery Voltage: 3.10 V
Battery percent: 92 %
TSP:MSG:SEND 101-101-0-0 s=255,c=3,t=0,pt=1,l=1,sg=0,ft=0,st=ok:92

Meshx86

can Li 18650 3.7 batteries be used as they are rechargeable ? knowing the max voltage at full might reach 4.1-4.2v ? maybe keeping the voltage regulator ?

mfalkvidd

@Meshx86 yes they can be used but as you've already identified the nrf (and maybe other components) will need to be protected from the high voltage when the battery is full.

The self-discharge rate of li-ion is higher than alkaline batteries which might affect how long the node can run before it needs charging.

💬 Battery Powered Sensors

21

11.7k

11.2k

113.1k