Weather station project, The weather is out there

[nuumio]

The weather is out there and so the weather station must be out there too. My weather station (or what will someday be a weather station) has now spent last two nights outside on my backyard. The idea is to test how it, and especially its lead acid battery, survives in cold weather.

My test setup is very simple: The battery and components on a breadboard (remote unit) are placed in a plastic box (with closed cover). The battery also has its own small box just in case it freezes and cracks in the cold. The remote unit sends SHT15 sensor's temperature and humidity readings to main unit about every 10 seconds. The main unit shows readings on LCD display and forwards readings to PC which logs readings to a database.

Test setup

Testbox on the ground

Testbox on a stool

The main unit couple of minutes ago. Hey, it’s getting warm

So far everything has been running just fine. I placed the testbox on the ground for the first night but it didn’t seem to catch lowest temperatures (it should have been below -20°C but I got only about -16°C). This was probably because it was the first time in this winter getting as cold as it was and the ground was still a bit warmer. After placing the test box on a stool it worked better. Last night it got to about -21°C. The battery also seems to be working well.

Currently I have 16125 rows in the database. 5 rows have corrupted data caused by a bug I found earlier and left there to test communication errors in serial link (I wasn’t expecting corrupted data to end up to database at that point). If all the other rows really are uncorrupted (as they seem to be) this test has been a success so far. I’ll leave the testbox outside for another night just go get a bit more testing time.

Below are graphs of temperature and humidity data I’ve got since about 20:00 this evening. I have cut out some of the data from the beginning so graphs start when the temperature inside the box got below 0°C after I placed it outside. Can you spot when I took the box back inside for awhile to shoot some photos of it?

Temperature graph [2010-11-29 03:54:04 - 2010-11-30 20:04:12]

Humidity graph [2010-11-29 03:54:04 - 2010-11-30 20:04:12]

And last but not least a little “Aww-effect” I shot yesterday in the backyard.

Aww-effect from backyard

 

[emuller]

There seems to be a mistake

There seems to be a mistake in your calculations.

From the graph, it seems that the outside temperature is a bottoming out at -20 degrees.

At this temperature, your eyeballs would drop out of your skull, your brain would turn into a slushy and your lungs will try to shrivel into something the size of a rasin and escape through your anus.

At least, that’s what I was told.

 

-20 degrees??? who lives in that??

 

p.s. looks great!.. but cooooold.

 

[nuumio]

The trick to survive…

The trick to survive at these temperatures is to consume enough antifreeze

At least here around Central Finland temperatures at -20°C and below aren’t that bad because usually there’s no wind. Of course it takes at little to get used to it. When the wind starts to blow the wind chill really bites you to the bone even if the temperature isn’t that low.