# Sensor reading consistency

**URL:** <https://discourse.nodered.org/t/sensor-reading-consistency/77915>\
**Category:** General\
**Tags:** node-red-dashboard\
**Created:** [25 April 2023 12:28 UTC](https://discourse.nodered.org/t/sensor-reading-consistency/77915 "2023-04-25T12:28:06Z")\
**Posts on this page:** 5\
**Page:** 2

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**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [26 April 2023 14:03 UTC](https://discourse.nodered.org/t/sensor-reading-consistency/77915/21 "2023-04-26T14:03:20Z")

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The air conditions around the sensor are clearly significant. I'm not sure that "a bit of air flow" is the best recipe for getting the most accurate output.

Alas I do not have a Stephenson Screen to put them in.  
Instead I gathered the four sensors indoors, close together but not touching, so the airflow over each should be similar.  
The 4 ESP8266s are all powered by a single 4 port USB power supply, though the USB cables are not matched.

I paid no attention to the orientation. It's not improbable that a board with the sensor facing down might register slightly warmer than one facing up.

The gross error in one of them is clearly related to a high resistance solder joint.

> changing your ESP8266 code so that the BME280 will be in deep sleep and only will be waked up for a measurement

The ESPs run Tasmota. My Node-red control flow can turn on deep sleep and I do intend to compare the results with that. But I suspect that the BME, wired to VCC and GND will still be powered up when the ESP is asleep. I'll have to use a GPIO pin to power the sensor.

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**Author:** ![mudwalker](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@mudwalker](https://discourse.nodered.org/u/mudwalker)\
**Post date:** [26 April 2023 14:19 UTC](https://discourse.nodered.org/t/sensor-reading-consistency/77915/22 "2023-04-26T14:19:10Z")

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> [@jbudd](#):
>
> The gross error in one of them is clearly related to a high resistance solder joint.

Excellent find! I have been soldering microelectronics for years, even changing simple SMD devices with a soldering iron, and still get the odd bad joint. I now check with an eyepiece to see the joints are bright. It was far easier, if a little more toxic, with the free flowing lead based solders. 🤣

My ESP8266 all run on Tasmota as well. Found it easy to install and configure. Also good if you might have comms problems for MQTT/NR flow errors as you can just log straight in to the sensor unit and see what it reports.

Good luck with new devices should you decide to replace.

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**Author:** ![cameo69](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cameo69/32/66593_2.png) [@cameo69](https://discourse.nodered.org/u/cameo69)\
**Post date:** [26 April 2023 15:43 UTC](https://discourse.nodered.org/t/sensor-reading-consistency/77915/23 "2023-04-26T15:43:39Z")

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> [@jbudd](#):
>
> My Node-red control flow can turn on deep sleep and I do intend to compare the results with that.

Would you be so kind and share the results. I would appreciate this.  
I am using BME280s as well and while they mostly work well, I did not find a good solution to put them in some sort of housing without them measuring 1-3 °C more but inconsistent (meaning I cannot simply subtract a fixed value).

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**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [1 May 2023 16:03 UTC](https://discourse.nodered.org/t/sensor-reading-consistency/77915/24 "2023-05-01T16:03:37Z")

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I'm not ignoring your request for more info around deep sleep, but it is proving difficult.

I can tell if a device is sleeping by the Last Will & Testament MQTT, though there is a lag reporting offline (equal to the Keep-alive time - 30 seconds?)  
By this measure, ESP #3 seems to wake, report and sleep again over just a few seconds  
 ![Untitled 1](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/f/c/fc6e24377e3b889c19c013eb10e7b0ed53d6c045.jpeg)

But #1,2 & 4 wake up, report more than once (I have experimentally set teleperiod to 60s) and stay awake for well over a minute.

 ![Untitled 2](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/b/c/bcef657aea8ea526b9290da9a2214c4549a05d54.jpeg)

So far I'm struggling to understand this behaviour.

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [30 June 2023 16:04 UTC](https://discourse.nodered.org/t/sensor-reading-consistency/77915/25 "2023-06-30T16:04:30Z")

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Closed on 30 June 2023 16:04 UTC

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