Humidity Sensor

Hi

I got a SHT15 BOB from Sparkfun. In my room it worked very good but as I putted one outside the problem began. For 2 hours the data were corect Humidity: 80% Temp: -5C But then the sensor jumped to Humidity: 114% Temp: 15C which are complety wrong values for outdoors.

Now the sensor is broken it always shows Humidity: 114% Temp: 25C even if I take it indoors...

Does someone have similar problems wiht the SHT15?

Thx Andy

I haven’t stuck mine outdoors yet. It’s been working fine indoors for a few weeks now.

Did it get rained on? I would think that you don’t want to get liquid directly into the sensor port. Or dew. How long have you had it back indoors with it still giving bad readings?

Is the increase in temperature correct or incorrect? Was sunlight hitting it or the wall below it? My experience with temperature sensors is that sunlight can easily cause at 10C or more rise above true ambient temp. Are you making sure to keep it in idle mode for at least 90% of time to prevent self-heating? Is it mounted in a way to keep heat from the rest of the circuit out of the sensor?

no rain felt on it because it's in a Solar Radiation Cover.

I think it's a voltage problem. As long as I power the sensor with 5v from an Arduino it works fine but as I switch to 3.3v the values show 5C off...

after half a day the sensor does work again..., strange...

So I tried again putting the sensor outdoors but after 30min again the sensor has locked it self and shows weird data:

68.75,-4.31,095264,551,8.55,378,48,0$

6.14,-25.0,095257,551,7.25,378,48,0$

114.89,14.78,095253,552,6.16,379,48,0$

The Numbers are: humidity in %, then temperatur, preasure, light, temp inside the box where the arduino is, the voltage, and if the solar panel is charging the battery or not.

They are sent over an Xbee every 2minutes. First data set is ok but then it gets weird.

Why does this sensor behave like this?

Thx Andy

I've got mine stuck out the window. I'll see what happens, but at 10C it's a bit warmer here than what you've got. I'm also running at 5v.

Have you tried running at 5v outdoors? Are the data & clock lines also at 3.3V in the outdoor setup? Are there any other differences between the outdoor system and the indoor testing?

OK i will try running the sensor at 5v outdoors. The data and clock runs at 3.3v like the hole arduino and there are no difference from the outdoor system to the one indoors.