Battery Powered ESP8266 Temperature/Humidity Monitor with DHT11

Hello adam,
awesome Project! Unfortunately I am a rookie here an not keen
in programming at all, so I just copied your Project with a DHT22.
Connection to mydevices works fine, but any Idea why I stuck in a Humidity loop?
Setup[20383] Connecting to xxxxx
[21886] Connected to WiFi
[21886] My IP:
[21886] Connecting to
[22319] Ready (ping: 152ms).
Entered Humidity
Humidity: 43.90
Entered Humidity
Humidity: 44.70
Entered Humidity
Regards Erik

I’m not exactly sure to be honest, but I would suspect that the differences between the DTH11 and DTH22 are enough that my code doesn’t work copied and pasted. I have a DHT22 that I can try later (haven’t even taken it out of the package yet). I’ll get it working and upload the code for you.

I also forgot to update how long it lasted. With 2 AA batteries this project updated the dashboard from 9/22/16 to 10/11/16 - 25 days! I have 2 AAA batteries hooked up now to see how long they will last.

I got it fixed!
(You must define all three Graphs in the
dashboard, for data handshake, otherwise
the routine does`t run trough…)
[7597] Ready (ping: 2172ms).
Entered Temperature
Temperature: 73.94
Entered Humidity
Humidity: 53.90
Entered Heat Index
Heat Index: 73.34

Got all values - sleeping



Made a mistake on Ebay and had 3 boards arrive on which to mount an esp-12 not the esp-12s.

Re-ordered hopefully the right items.

The battery holders and DHT11s arrived ok and I bought some boxes from a charity shop.

Should be good to go soon.

The AAA batteries didn’t fare very well. They only lasted 3 days, but there could have been a Cayenne outage in there that drained the batteries. I have some LiPO laptop batteries that I’m going to try as soon as my HT7333 voltage regulators are delivered from China (hopefully soon - ordered them 2 weeks ago). These voltage regulators have a very low voltage drop (90mV as opposed to the 1.1v on the AMS1117) and will allow the ESP to run for longer when the battery voltage hits less than 4.4v.

ESP12s now arrived. Aim to make up 2 or 3 modules.

IDE setup and sketch verified - just need to get the soldering iron out.

I think I will wire in a programming socket to make it easy to connect the FTDI module as I may use these to record temperatures in other places, so it this would make it easier to change the WiFi settings.

Really interesting project.

I already have a dht11 on a nodemcu running, but looking into making it battery driven.

Have you thought of monitoring the battery volts if possible? and ofcourse transmit the value to cayenne, and then be able to trigger a mail when getting low.
Or would it be more logic to just send a mail when it has been silent for too long?


I think there is a lot we can do here.

  1. Power your DHT module using I/O so it isn’t a parasite.
  2. Use an efficient switching regulator vs. a linear regulator.
  3. Evaluate whether MQTT gets messages through faster.
  4. Using a Lipo along with a switcher, we can discharge to 3.3V and still maintain regulation, getting 90+ discharge out of the battery.
  5. Investigate incorporating a solar cell to harvest a bit of energy.

Looking forward to trying dis.



Never thought about the DHT being on all the time, I’ll definitely do that.

The HT7333 regulator I have on now only drops 90mV and the Quiescent Current is only 8 mA max. What did you have in mind? The major downside to the HT7333 is that its legs don’t line up with a standard perf board so it’s a pain to solder it in. To get one up and running quick I ended up soldering some solid wire the board and then soldering the HT7333 to the wires. Definitely need to look in to a better way to integrate them.

I’m not checking if the message got through or not, just sending and praying it makes it. Easy enough to run a check on the last date stamp received on the MQTT server and send an alert that data is not being received.

I have a lipo and a charger that I am going to hook up after these 4AA batteries finally die (been running for 2 days shy of a month and still have mover 3.3v left). My concern with the lipo is draining it completely dead, which I’m assuming you were referring to with the switcher. What do you have planned there?

I’ve also been contemplating this, just haven’t pulled the trigger on a solar panel yet. The lipo charger I have supports charging and a load up to 1A so it should work absolutely fine with the ESP. Might order one tonight!

You can monitor the VCC volts using ADC_MODE(ADC_VCC); below your defines (basically before the setup function) and then call vcc = ESP.getVcc(); to get the voltage. I haven’t had much luck with it being accurate, but it has been consistent. If you monitor the value of VCC you could come up with a conversion formula.

After doing some googling it looks like it is possible to solder it right to a perf board, just have to be very careful. This guy pulled it off.

Get something like this, and you get a sleep current of less than 500 uA with a LiPo supply.


Oops, meant to say the HT7333 uses 8 uA max (according to the datasheet anyway) in my last post. My only problem with that module is that is only accepts up to 6v, but I like that it comes with headers on it. Might order a few of those if I can find it on amazon.

I mean…really. I can BARELY SMT solder an ESP12-e.
The smaller SMT stuff- cripes, I can’t even see it clearly enough to solder.

If things continue to shrink,
I’ll be required to pay an independent assembler
to build it for me!

Can you specify the AA batteries you use? Normal oder rechargeable ones? Which capacity?

Any AA batteries will work. Specifically the ones I used were from Amazon (Amazon brand) but I also have some 2700mAh POWEREX AA rechargeable batteries that are that are really good and I use a POWEREX charger as well I think when I ordered the charger they threw in the batteries for free but it was about 4 years ago so it may be a separate purchase now.

I’ve actually moved on to recycling old laptop batteries to power this project now I use this for the charger for the batteries with no fires (yet). I’ll update the post after MQTT is released.

1 Like

Tried to modify this for HTU21d with is much more accurate then the DHT sensors.

But like the other project i tried with cayenne and nodeMCU this seems not to work.
Is here anybody who got cayenne and nodemcu working???

My monitor output:
bBÊdžBrûΦêöÿSetup[269] Connecting to networxSAVE2
[2272] Connected to WiFi
[2272] My IP:
[5001] Connecting to
[10247] Connecting to
[10495] Connecting to
[10740] Connecting to
[11157] Ready (ping: 170ms).
Entered Humidity

Exception (28):
epc1=0x40203e9d epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

ctx: cont 
sp: 3ffef6e0 end: 3ffefac0 offset: 01a0

3ffef880:  3ffe8500 00000000 3ffee9dc 40203e99  
3ffef890:  3ffee794 3ffee79c 3ffee9dc 40203f4b  
3ffef8a0:  40102a7d 3ffefa04 3ffee9dc 40202987  
3ffef8b0:  00007fff 00f85e25 3ffed490 40102c0c  
3ffef8c0:  3ffe9858 00000000 00000000 00000000  
3ffef8d0:  00000000 00f85e25 4010304a 00000100  
3ffef8e0:  7fffffff 3ffe9858 3ffe9858 00000001  
3ffef8f0:  00000001 00007fff 00000000 4000050c  
3ffef900:  401030e7 00f85e25 00000000 4000050c  
3ffef910:  3fffc278 40102de4 3fffc200 00000022  
3ffef920:  3ffefa03 00000000 0ccccccc 00000009  
3ffef930:  00000019 00000001 00000000 3ffefa05  
3ffef940:  00000000 3ffe8cec 00000001 3ffefa00  
3ffef950:  00007276 3ffefa04 3ffee7a0 4020101c  
3ffef960:  3ffefa04 3fffc6fc 00000001 4022333d  
3ffef970:  3fff0b74 00000000 3ffeea98 3ffefa00  
3ffef980:  00007276 3ffefa04 00000000 40202c4c  
3ffef990:  3ffefa00 3fff0b74 3fff0a44 40203c85  
3ffef9a0:  40204a00 3ffee7d4 00000030 40203ce6  
3ffef9b0:  40204b0a 3ffee7d4 3ffeeaa0 3ffefa03  
3ffef9c0:  3ffee7a0 00000004 40204ab8 3ffeeaa0  
3ffef9d0:  00000005 3ffefa00 3ffee7a0 3ffefa00  
3ffef9e0:  00000004 00000001 3ffee7a0 40202ec2  
3ffef9f0:  00000000 3ffee7c0 3ffee7a0 40202d24  
3ffefa00:  30007276 3fffda00 3ffeea98 00000030  
3ffefa10:  04000314 00002000 3ffeeaa0 3ffee7c0  
3ffefa20:  00000004 3ffefa00 40204ab8 3ffeeaa0  
3ffefa30:  3ffe84a0 000020fa 3ffee7a0 00000001  
3ffefa40:  00000000 3ffee7c0 3ffee7a0 402030b5  
3ffefa50:  00000000 ff000000 01c8a8c0 40201513  
3ffefa60:  3fffdad0 3ffe8358 3ffee7ec 40202709  
3ffefa70:  3ffee7c0 25c8a8c0 feefeffe feefeffe  
3ffefa80:  3ffe834c feefeffe 3ffee9dc 3ffeea98  
3ffefa90:  3fffdad0 00000000 3ffeea90 402030f1  
3ffefaa0:  3fffdad0 00000000 3ffeea90 40204b04  
3ffefab0:  feefeffe feefeffe 3ffeeaa0 40100718  

My modified sketch:

#define CAYENNE_PRINT Serial
// #define DHTTYPE DHT11
// #define DHTPIN  14

#include "CayenneDefines.h"
#include "BlynkSimpleEsp8266.h"
#include "CayenneWiFiClient.h"
// #include <DHT.h>
#include <SparkFunHTU21D.h>

// Cayenne authentication token. This should be obtained from the Cayenne Dashboard.
char token[] = "";
// Your network name and password.
char ssid[] = "";
char password[] = "";
//Variables for DHT11 values
//float h, t, hif;
float h, t;
bool Humidity = false;
bool Temperature = false;
//bool HeatIndex = false;

HTU21D myHumidity;

void setup()
  Cayenne.begin(token, ssid, password);

  Humidity = false;
  Temperature = false;
  //HeatIndex = false;

void loop()
  //Run Cayenne Functions;
  //Check if we got all values we wanted and sleep for 10 minutes if we did
  // if (Humidity && Temperature && HeatIndex){
    if (Humidity && Temperature){
    Serial.println("Got all values - sleeping");
    ESP.deepSleep(60000000, WAKE_RF_DEFAULT);

  Serial.println("Entered Humidity");

  //Check if read failed and try until success
  do {
    //Read humidity (percent)
    // h = dht.readHumidity();
    h = myHumidity.readHumidity();

  } while  (isnan(h));

  Serial.print("Humidity: ");

  //Set Humidity to true so we know when to sleep
  Humidity = true;

  //Write to Cayenne Dashboard
  Cayenne.virtualWrite(V0, h);

  Serial.println("Entered Temperature");
  //Check if read failed and try until success
  do {
    //Read temperature as Fahrenheit
    // t = dht.readTemperature(true);
    t = myHumidity.readTemperature();

  } while  (isnan(t));

  Serial.print("Temperature: ");

  //Set Temperature to true so we know when to sleep
  Temperature = true;

  //Write to Cayenne Dashboard
  Cayenne.virtualWrite(V1, t);

  Serial.println("Entered Heat Index");

  //Check if read failed and try until success
  do {
    //Read humidity (percent)
    h = dht.readHumidity();
    //Read temperature as Fahrenheit
    t = dht.readTemperature(true);
    //Calculate Heat Index as Fahrenheit
    hif = dht.computeHeatIndex(t, h);
  } while  (isnan(t) || isnan(h));

  Serial.print("Heat Index: ");

  //Set HeatIndex to true so we know when to sleep
  HeatIndex = true;

  //Write to Cayenne Dashboard
  Cayenne.virtualWrite(V2, hif);
} */

Ok, i just want to get a feeling for the capacity in mAh which is consumed per day/week.

@kuncono has made several projects using NodeMCU. hey @kuncono, Do you think you can see if you can help out @pearl3? :slight_smile: