Does anyone else have issues with accuracy/consistency of DS18B20 sensors?

I have two D1 Mini’s, running Tamota, with DS18B20 temperature sensors. I have both of them right next to a Sonoff (far enough away to be influencesd with any radiated heat from the Sonoff), running Tasmota, with a BME280 sensor and there is a substantial difference in readings between them. Currently they are:

DS18B20 sensor 1: 24.2
DS18B20 sensor 1: 23.7
BME280: 21.2

I know that I can set a float in HA to bring them inline, but the DS18B20 do not seem to be consistent in that I have adjusted the float several times but after some time them are misaligned again.

I believe that the DS18B20 can have different resolutions, using 9 up to 12 bits, but I have no idea of what Tamota runs at as default, or whether it can be changed, but even at 9 bits I would expect them to have a more consistent temperature.

Not sure which one you have but data sheets seem to point to a ±0.5°C Accuracy. This reflects the data you have. Worse case these two sensors could be 1 degree apart and within spec.

https://components101.com/sensors/ds18b20-temperature-sensor

Even given a ±0.5°C accuracy, there is no way my living room is currently at the temperature they are reporting. The BME280 (top figure on table below) is more like the real temperature:

Screenshot%20from%202019-12-03%2022-14-53

Are these temp sensors exposed to light(not shielded?) If so that will affect the readings, and it seems you are reading high so it makes me wonder.

They are not exposed to any direct sunlight or any other heat source that the BME280 is not also exposed to. Below is a picture, the BME280 is in the sensor enclosure.


Screenshot%20from%202019-12-04%2007-00-36

Did you get it working?

I just got three DS18B20 and ESP8266 with Tasmota and have a higher temperature in my living room (around 31°C instead of 23°C) and in my fridge with <10°C I got 18.9 / 19.9 and 21.2°C from the DS18B20

Greetings, fragless

:point_down:

I got them from Tasmota ioT WiFi DS18B20 ESP8266 Temperatur Set – IoT powered by androegg.de
It is a complete set of ESP8266 with tasmota already flashed and a second circuit board with powersupply/-converter and the DS18B20

according to the images they look like original
I compared it with 433MHz-temperature-modules (also not really calibrated) - in my flat and the fridge - and the DS18B20 deliver around 7°C more than it should be

I could make offsets, but I wrote here because maybe there is a logic mistake what I made (because from bedfellow they also measured more than it should be)

But I will write a mail to the reseller, maybe he has an idea