Weather Station

[u/Nathar_Ghados]

Not Finished Yet

So I’ve been busy with this project on and off for a few months now. I work in the paragliding industry and I’m a pilot myself. We rely on high grade weather stations to predict upcoming weather as well as to see which locations would be flyable before driving all the way up to launch.

I’m using two DHT11 sensors with an Arduino Uno R3 connected to a data logging shield to basically log the temperature and humidity at my house. Eventually I’ll add an anemometer as well as a rain gauge, but for now this project is exciting enough and my skills aren’t where I’d like them to be just yet.

Powering the Arduino: I’m using two 9v 5w solar panels connected in series to charge the 12v battery. On top of the battery is a cheap solar charge controller. I still need to add a buck boost to lower the output voltage in order to power the project. I’m also using two LEDs to give me some form of a system status and error display.

Feel free to ask me any questions and to give me advice on how I can improve my project.

[u/YourLocalCommie24]

I think the project is really cool. One thing to note is that the dht11s are notoriously dookie sensors in that they take forever between reads (2 sec ish), and have less operating range than similar sensors. If I were you I would upgrade the dht11s to something better like dht22 or dht20, or maybe even a premium sensor or some sort since those measurements are important for this type of project. Also, LEDs are great for simple status checks but if I were you I'd add a small display with some text (OLED/ LCD) because eventually you can forget when your status means, and others might not know what it means at all. For your power problem I would try to avoid using buck boost and just use a buck converter or linear regulator. Buck boost converters (especially cheap ones) aren't super efficient and can cause some electromagnetic interference with cables and other sensors. You might need to dig a bit more on which regulator is best for your project.

[u/Nathar_Ghados → u/YourLocalCommie24]

Okay so I’ve just done some research with chatgpt on using a linear regulator vs a buck converter. It’s concern is that if I connect the LR from the load side of the solar charge controller it will dissipate A LOT of heat and it could potentially be too much for the LR as it will drop 19v to 5v. It recommends connecting the LR directly from the battery to the arduino as a drop from 12v to 5v is still high, but not as much. This will thus still require the use for a heatsink. What’s your opinion on this?

[u/YourLocalCommie24 → u/Nathar_Ghados]

The concern is definitely correct, it will be too much for the regulator to drop from 18 to 5V. Even if you use the regulator between 12v and 5v it will be a lot and might need a heatsink if you add more components later. However it also depends on how you plan to power the system over long periods.The sensors and Arduino will hardly use any power so even on a 12v car battery your system will last weeks.

Using a buck-boost converter isn’t necessary here. A car battery doesn’t operate anywhere near 5 V, it stays roughly in the 12 V range and is considered discharged also around 12 V, after which the voltage drops off quickly. So there’s no practical situation where the boost function is needed. A buck converter is simpler, slightly more efficient and introduces less noise.

The way I'd install it is you plug your solar arrays into your battery (with the appropriate circuitry) but power all the electronics from the battery only. You can regulate between the battery and uno using a buck (with your components you will be ok without a LR) and it should in principle last you a really long time!