For a while I have been looking for a way of getting a reading of main and leisure battery voltage, and inside and outside temperature in the van. I spent ages on researching and found some bits here and there that might help, but nothing to do the whoe job, and nothing really satisfactory, until finally I found a link to the Arduino website. Never having heard of it before, I did a bit of reading and it seemed perfect. So I set about designing and building the necessary circuitry … below is a brief summary of what I came up with. Before I go on I should tip my hat in this direction – seems like tobes49 thought of it first: http://www.vwt4forum.co.uk/showthread.php?t=198976
First, the Arduino is a small board that allows monitoring of sensor inputs on one of many analogue or digital channels. Its really simple, you just write a short bit of code to tell it what to monitor, upload it to the chip, and away you go. Find more details at www.arduino.cc. There are several versions; I based my project on the Uno R3. As for sensors, you can sense just about anything for pennies. Have a look at www.proto-pic.com or www.oomlout.com for example. I did think about using the Raspberry Pi for this project, but once I found the Arduino I realised the RPi is massively OTT.
I’m going to jump straight to the end result – I’m sure you aren’t interested in the two months of development, debugging, pulling my hair out trying to get it to work. The final circuit has the following functionality:
• 2 temperature sensors, one mounted inside the van, the other behind the front bumper
• Measures the voltages of the two batteries
• Monitors a three-axis accelerometer mounted in the van, from which it calculates pitch and roll angle;
• Monitors the state of a button, used to display either main/aux battery volts, inside/outside temp, or pitch/roll angle
• Displays warning if either battery or temperature is out of set range
To implement the circuit, I bought some copper board from Maplin, and worked out how to wire the above circuit up so that I could attach it directly to the Arduino. Here is a photo of the completed circuit mounted on the Arduino (which is underneath so you cant see it).
Read more: Arduino powered voltmeter and temp gauge