Hello. I’m trying to use a RuuviTag Pro as an outside temperature sensor in my camper van. I’ve mounted it in several places under the van, away from direct sunlight, exhaust, or even airflow under the van. No matter what location I try, the temperature from this sensor always starts out correct after the van is stationary for a while (it matches the accurate sensor built into the van), but then it quickly increases to become higher than the actual outside temperature by about 10 degrees Fahrenheit within a few minutes of the vehicle moving. Then it will stay about 10 degrees too high for hours while the van is moving before returning to an accurate reading a few hours after the van stops moving.
This happens in the summer and winter and also during the day and night. So I don’t think it is related to things like sunlight reflected off the pavement, or retained heat in the pavement, etc. I thought it might be related to airflow through the barometric sensor port on the 3-in-1 Pro sensor so I even ordered a 2-in-1 Pro sensor to see if that helped. Both sensors are doing the exact same thing, so I don’t think it’s a bad sensor or related to the barometric pressure port.
Does anyone have any ideas about why I can’t get an accurate temperature reading from any position underneath a moving vehicle? Thanks in advance.
Since the RuuviTag matches the sensor in van when van is not moving, my first guess is that something in van generates heat that gets coupled into the frame of van and then to RuuviTag itself. It could be anything, e.g. engine block, exhaust pipe, brakes, heating inside van…
I know that RuuviTags have been used to measure road temperature conditions, but that company ended up making their own custom 3D-printed enclosure which was designed to keep radiative heat and water out while letting airflow in and insulating the sensor from the body of the car.
You could try adding some kind of plastic as a insulation between the sensor and van body and do your best to keep the sensor as far away from hot parts of the car as possible, or if you are more interested in temperature while moving you could use the sensor offset calibration at -10F to display corrected temperature while on the go.
Ok thanks. I’ll try to insulate it from the mounting point somehow. I’d thought about that, but it seemed unlikely since I’ve mounted it to so many different types of mounting points and the behavior is always the same. Right now it’s mounted on the side of the trailer hitch as far away from any heat generating components as possible and still doing it. I thought it could be friction from airflow too, but even putting it in spots with almost no airflow didn’t seem to help.
I’ll try something more aggressive like an enclosure or insulator. Thanks again.