TentBox

Powering our adventures

This idea struck me one night before a trip—a way to simplify power distribution and avoid a mess of battery packs in my rooftop tent. The LED strip in my Smittybilt Overlander XL consumes about 10W. Lugging additional battery packs for the LED strip seemed clunky, especially when there’s a capable battery in the truck bed that could power the lights and charge phones. Why not run a single power cord from the 12V plug in the bed up to the rooftop tent?

That would be easy, but a simple 12V extension cord and USB charger felt too basic. I wondered, “How can I make this more interesting?”. For a while I have been itching to tinker with ESP32 boards since exploring Meshtastic and LoRa. So I thought, why not add temperature and humidity sensors for some environmental monitoring?

The idea was born! I had to get up and sketch it into my phone, promising myself to work out the details in the morning.

The “TentBox” is an admittedly over-engineered box that brings power to the rooftop tent while providing temperature data. I must say, this box has proven incredibly useful both in the tent and on our various adventures and road trips.

The Build

I started with the ESP32 board, getting the sensors to work and display data on the OLED screen. Fortunately, this task wasn’t too challenging – thanks to the wealth of tutorials online, you can get an ESP32 up and running with the Arduino IDE in no time. Next came the wiring. I spent more time than necessary on this, but eventually got the sensors working off the breadboard and reading data within 2°F of another thermometer. Good enough, considering these sensors aren’t known for pinpoint accuracy.

With the wiring complete and code flashed to the ESP32 board, I was ready to roll!

Next up was case design. This was exciting, as I had a shiny new 3D printer I was eager to use for prototyping.

Sizing the OLED screen was straightforward. Designing the mounts and deciding where to place the sensors and 12V ports only took one or two prints to figure out.

v0.1

With the box built, it was time to test. The box performed great on our first trip, doing exactly what it was designed to do. However, I noticed that the ESP32 board occasionally freezes up and stops displaying data. This is an issue I’m still trying to resolve. Fortunately, the way the box is wired, the ESP32 board is powered separately from the main 12V plugs, so I still have power even if the screen and board aren’t functioning.

What’s Next?

I need to iron out the quirks with the ESP32 board. I suspect voltage drops might be causing the board to lock up.

Also, since there’s onboard Wi-Fi, it opens up the possibility of creating a simple web server to display temperature data when you’re out of sight from the screen. This means you could connect to the board’s Wi-Fi and read the data from anywhere within range. Cool, right?