This has been a project to replace the existing electronics in the purely motorhome end of the van for many years and while bit shave been constructed, never been installed, until recently, when the fridge thermostat and motor controller started to act up, prompting an Arduino solution.
Arduino is an open source hardware platform based around the Atmel series of microcontrollers specifically adapted to be easy to use and a quick search of the internet will bring up millions of hits for a wide range of projects people around the world have made based around it. There's lots of help for anyone who wants to learn and lots of cheap teaching kits. These aren't small computers like the Raspberry Pi, but much simpler and cheaper, think under £3 for standard Nano model, and if you are prepared to do your own soldering, under £1.
So, having decided to now get on with it, here is my current order of projects to replace functions in my van with Arduino.
Replacing the basic thermostat of course, but also proving additional enhancements, such as multiple temperature sensors (top and bottom and freezing compartment), multiple compressor speeds, internal fan to circulate cold air rather than turn on the compressor and also control the external fans to ensure that trapped warm air is ejected. As well as these, add controls to allow an inverter powered mains fridge to operate efficiently, controlling power to both the inverter and fridge to reduce power consumption as well as the big cost saving of running a domestic fridge in place of a 12-24V specialist compressor fridge. Finally, run a small temperature meter display so the actual fridge temperatures can be seen.
Central Display and Control
I've run a CBE system since the days we converted the van so I'm used to a microcontroller based system and the central control unit that is provides. This is a central console function that will sit in an easily accessed position that will display the information from other functions like the fridge controller, and let the user control them remotely. I've only aimed at one controller but there's no reason why a van can't have two, one at each end say. The big advantage of taking this approach is avoiding running lots of wires round the van to switches, the aim being just a few control wires from the controller. I'll add a clock and outside/inside temperature and humidity monitor.
Having looked at the options for joining it all together, settled for ethernet, mainly on cost and ease of interfacing it. The components are common, the basics I can get from a hardware store, joining it to computers and wifi is easy and it can be either very simple or very sophisticated, my choice. Adding ethernet to the fridge controller was just a case of plugging in the module and adding the software.
There are lots of ways of using motorhomes, but modern life in one depends so much on power sources, and if the van is one which is truly mobile, it will have to rely on batteries. Not ignoring mains hook up, lots of vans spend a lot of their time that way, but finding out that the batteries are dead can be a real pain to be avoided and looking after them worthwhile. This branches out into several other projects following but the core one is to provide a current in/out monitor as well as a state of charge estimate. Displays on its own unit or the central display.
This most fundamental of tools puts charge into the batteries for future use. The idea is to produce an addition to the battery monitor which takes current from another source, such as the mains, solar or alternator, and safely puts it into the batteries. Displays and controls on its own unit or the central display.
Putting solar panels on your van is one of the big technical things van converters do, and there's lots of systems and lots of advice about. Well this is a project to make a solar controller where the user can see exactly what is going on and decide how they want their solar panels to run, preferably automatically and without intervention! Displays and controls on its own unit or the central display.
Vans have this big power source in them, the engine, which for the time being is fossil fuel driven, but which can generate a lot of power to charge batteries. It's not designed to charge your leisure batteries by itself, but with a bit of help can be used to supply power to a battery charger to do so. This is a build a better B2B charger project.
This is 'the thing' these days, and might get introduced earlier on, the idea being to use 'off the peg' Android and IOS Bluetooth systems to display Arduino based data. This is always developing so may change as time goes on.
This can be for lots of things, but generally for adding switching to any electrical system that would benefit from it. Lights are a good example, especially dimmers, but also cooling fans and dehumidifiers as well as timer based switches.
Other things that might get done, but no plans for.
Wind power input, an inverter, an antitheft alarm, gas meter, CANBUS interface, and a mains controller.