Temperature reading hangs

#1

I have RuuviTag outside my house and use it to measure temperature. This morning it showed +22 C reading while the real outside temperature was -18 C. I went outside and picked up the Tag and heated it with my hands. No change in reading. Then I went inside and heated it more. No change in the reading.
All this time my RuuviScanner application showed that readings were being updated constantly so this was not due to communication problems.

Removing battery and putting it back of battery solved problem.

Maybe the battery is going to be dead soon. A battery from my another RuuviTag died about month ago. And I had kept it inside my house.

Anybody had same issues?

#2

I had a tag (temporarily) fail due to too much condensation forming inside the enclosure when the tag was buried underground and one of the symptoms was the temperature reading 21.65 C. Removed the battery and let it dry indoors fixed the issues. Perhaps failing temperature readings get interpreted as that temperature? The coldness shouldn’t be an issue for the tag itself, I have had one in the freezer for almost a year non-stop, varying between -22 C and -32 C. Humidity shouldn’t be an issue either as long as the tag is in “open air” and not buried underground for example, I’ve had one tag outdoors for almost a year non-stop as well, during the winter months the relative humidity is around 95% average.

The battery on the other hand might degrade much sooner at such temperatures, I’m using a CR2450HT extended temperature range battery in the tag. It could very well be that your battery is just dying and reading the temperature sensor fails for that reason. :thinking:

#3

My RuuviTag is located on top of a roof beam. It is not directly exposed to wind, rain or sunshine. Considering the weather now, humidity cannot be an issue in my case.

I am using CR2450HT batteries too. They are the one that were shipped with RuuviTags. Perhaps I got a bad batch since if this problem is due to battery already 2 out of 3 has failed in less than a year.

#4

With the “original” default firmware, the typical lifetime is less than a year with CR2450. :slight_smile: CR2477 has about a third more lifetime, but the biggest difference comes from the firmware and transmission interval, as transmitting data over BLE is by far the most power-hungry operation.

For logging purposes, it’s recommended to run a firmware that transmits a lot more rarely; the default firmware, by default, transmits multiple times per second which will drain the battery relatively fast. Transmitting once per 5-10 seconds should give around 7-ish years of battery life depending on other conditions

#5

Actually, the default FW in RAW mode transmits only one time a second and with a CR2477 battery you should be able to get 2-3 years. URL mode transmits at 2Hz.

#6

Correct, I meant the ‘kickstarter-era’ firmware which always sent at a higher rate. As @Jii mentioned CR2450HT which only shipped with kickstarter tags and the time matches with the expected lifetime of 2-3hz interval since the kickstarter tags were shipped almost a year ago.

Newer firmware support the raw mode, as you mentioned, but does not boot to it by default, at least the latest stable release didn’t seem to :slight_smile:

#7

Dear allm I have recently bought Ruuvitag and the readings of temparature are constant . Is it frozen 22 degrees all the time, even though the room is not that warm. anyways to reset or manufacturing defects ? Thanks Reddy

#8

Are you using RuuviTag in URL or RAW mode? URL mode does not update value automatically.

#9

Dear otso, Thanks for the reply. I am using the url in the android phone. Is there anyother way i can use the phone to get the updates ? I have tried also ibeacon / eddystone still the same. Thanks ahead

#10

Use RAW mode (press button B) and use our alpha version mobile app: