Battery powered sensor last 1 week

[scalz]

Hello.

I think, depending on how your sensor is connected, it is always powered on. Your node is sleeping but you would need to use a mosfet to power off the sensor when you don't use it. Or use an IO pin to deliver the power instead of a "mosfet switch".

[Martin Tellblom]

@scalz said:

always powere

Alright, as you proberbly understand I'm not a electronics engineer :) so please explain that to me.
This is how its setup:

Everything is build on @sundberg84 Easy/Newbie PCB (This is my LAB PCB that I try out on before soldering, easier to chane components to see if someone of the cheap once are broken)

Sensor Vcc connected to 3,3V, GND to GND and sensor to D3.
So what do I have to do to turn of the sensor when I put the arduino to sleep?

[sundberg84]

@Martin-Tellblom - instead of wire power from VCC to the sensor you could try power it through D3 or another IO pin.
Then you set this pin to HIGH to power the sensor and then LOW before you sleep the node.

If you have a multimeter you could measure the ampere when you sleep the node.

[Martin Tellblom]

@sundberg84 said:

to HIGH to power the sensor and then LOW before you sleep the node.

If you have a multimeter

Alright so if I connect the Vcc sron the sensor to D2 (since I use D3 for measurement) and set that HIGH before I measure, should I have a sleep for it to power up aswell?

Something Like this?

  digitalWrite(SOIL_POWER_PIN , HIGH);  
  delayMicroseconds(25);

  moisture = analogRead(SOIL_SENSE_PIN);
  
  delayMicroseconds(25);
  digitalWrite(SOIL_POWER_PIN , LOW);  

[sundberg84]

@Martin-Tellblom - Yes, something like that.
Dont use delay, use wait(); if tou want to create a pause for reading.

[Martin Tellblom]

@sundberg84
OK,

I have now changed to the below code and changed to a SOIL sensor with the LED still on

The LED is lit up even after digitalWrite(SOIL_POWER_PIN , LOW); so I don't think its working

void loop()
{

  digitalWrite(SOIL_POWER_PIN , HIGH);
  wait(25);

  moisture = analogRead(SOIL_SENSE_PIN);

  wait(25);
  digitalWrite(SOIL_POWER_PIN , LOW);

  if (oldMoisture != moisture) {
    send(msgSoil.set(moisture, 0));
    sendBatteryLevel(moisture);
    oldMoisture = moisture;
  }

  //Check Battery Level
  int sensorValue = analogRead(BATTERY_SENSE_PIN);

  int batteryPcnt = sensorValue / 10;
  if (oldBatteryPcnt != batteryPcnt) {
    // Power up radio after sleep
    sendBatteryLevel(batteryPcnt);
    oldBatteryPcnt = batteryPcnt;
  }
  digitalWrite(SOIL_POWER_PIN , LOW);
  digitalWrite(SOIL_POWER_PIN , LOW);
  sleep(SLEEP_TIME);
}

[Martin Tellblom]

@sundberg84

Stupid me, forgot defining it as output pinMode(SOIL_POWER_PIN, OUTPUT); in the setup

It's working now

[sundberg84]

Good! @Martin-Tellblom If you can measure how much uA it consumes in sleep() mode you can then calculate the life expectancy. Around 100uA is fine in my world with a booster and pro mini.

[Martin Tellblom]

@sundberg84 said:

can measure how much uA it consumes in s

I thought I could do that with my multimeter but I get no value

[sundberg84]

@Martin-Tellblom - Put the multimeter in series with VCC. Dont forget to change the input on your multimeter.

[cimba007]

@sundberg84

Be aware that depending on the mesurement range a multimeter could introduce a big burdan voltage.

Just simple and short: To measure in the mA range you the multmeter measures the voltage drop accross a series resistor with an value .. call it A.

Switching to the µA range the mutltimeter switches to a much larger resistor (e.g. 1000times A) to measure a significat enough voltage drop. With the wrong voltage range .. measuring µA while the board is consuming in the mA range might lead to a huge voltage drop and your circuit not working at all.

So do this:

• Switch to mA mode .. take your measurement .. wait until you KNOW for sure your circuit is in sleep mode (add some messages on the serial console) and THEN switch to µA range.

[Martin Tellblom]

I don't think my multimeter is good enough for this, It seems like it put in some power due if I

I will try this when I get home today and see if I need a new multimeter or not :)

[scalz]

and with a multimeter only, due to burden voltage and depending of the multimeter precision, you won't get the true power consumption, an approx which is still nice, you can know what "looks" power consumption and tendancy. Even if you're using a nice expensive Fluke. Best precision for this is uCurrent Gold+multimeter ;)

[Martin Tellblom]

@scalz

Or just simply take percentage and date/time and then a few days later see what has changed percentage wise ...
Its to simple I know but if 1% battery power equals 4 days the sensor probably last for about 9-10 month (the last percentage I suppose you don't get any communication with :) )

[sundberg84]

@Martin-Tellblom - Im not sure it works that way. It depends on which battery you use.
Voltage tends to drop faster in the end for normal AA batteries.

My sensors doesnt drop that much (maybe 5%) the first 6 months.

[Martin Tellblom]

@sundberg84 Hmm What you are saying is that I need to buy a new and better Multimeter :) This is the reason I was waiting for ..... :9

[sundberg84]

@Martin-Tellblom - I hope you dont give up! Battery operations was the hardest part for me to figure out...

[Martin Tellblom]

I only have two kind of sensors that I need to be battery operated and that's the plants warning that they are out of water and soon gonna die and the dogs water bowl warning that they soon gonna die (KIDDING). The dogs bowl I like to measure the levels and have that to compare with the temperature, just for fun.
I hope I get this working aswell, It wont be pretty with a cable around the few plants we got

[Nicklas Starkel]

@Martin-Tellblom , I'm in this mess as well. Just ordered a new Multimeter off aliexpress :)

@sundberg84 , have you tried other batteries? I bough some ultrafire 3.7V 8800mAh and will try these.
They were cheap so no loss if they do not work out..

[Nca78]

@Martin-Tellblom said:

Alright so if I connect the Vcc sron the sensor to D2

Hello, you should use another digital pin than D2 as it is used by MySensors library and on the EastPCB it is connected to the INT pin of the NRF24. I had problems using D2 pin before because of this reason. Use D4,5,6,7 or 8 and you will be sure to have no problem.