Westfalia Battery Monitor V1.0

It began with a sketch on a whiteboard just under a year ago, and today the device is functioning beautifully in my van. Granted, I only worked on this project for about 2 weeks last year before kayaking dragged me away from it and during the past 2 weeks, but it is still gratifying to finally have this project up and running after a year of contemplating it and finally resolving to get it done!

The Westfalia camper package in Volkswagen Vanagons is one of the coolest little toys you can imagine. It’s like having a house on wheels with a footprint no larger than an ordinary car. Or as I like to think of it, it’s like having all the subsystems from a satellite in the back of my vehicle, except for the fact that I can modify them electrically and mechanically without going through a multi-year design and approval process. When it comes right down to, I love to camp in the van, but the ability to modify it to suit my needs is the kind of play that really makes the van a hobby unto itself.

After I completed the engine conversion 2 years ago, I decided it was time for some proper refrigeration of beverages. You see, the original Dometic 3-way fridge was a neat little piece of equipment, but I spent substantial time tweaking and monitoring its performance only to realize that it just couldn’t cope with the heat of the summer. The mountains on my frosty Coors Lights just weren’t staying blue, and if there is one thing I can’t have, it’s a warm Coors light. After much research, I invested in an ARB Fridge/Freezer that is rated to maintain subfreezing temperatures in 90deg heat while consuming very little power. First off, let me say that the fridge is incredible, and it really does do everything they claim. But the fact of the matter is that power has to come from somewhere, and in my case, it came from an increasingly large and complex auxiliary battery system in the van. Then you combine this complex system with the notoriously unreliable Vanagon starter that masquerades its degrading performance as a battery problem, and you wind up with good ole’ Pat scratching out his remaining hair over the course of the past year trying to figure out what was happening in the van’s electrical system.

I believe that there are two ways to solve problems. The first and most conventional way is to simply attack the problem and try to get things done. It might be not be fun, but you end up arriving at the answer. I think of this as “work”. And work just isn’t that fun. The second, less traveled path, is to put a smile on your face and explore the problem for what it is. This approach not only gets you to the answer, but it takes you to many other cool, rewarding places along the way. I think of this as “play”, and this is the way I prefer to solve problems. So when I was faced with a difficult problem to solve in my van’s electrical system last year, I didn’t just take out a voltmeter and track down the offender. Nope, I decided that I would use it as an opportunity to explore the cool, new world of Arduino microcontrollers with the hope that I could design a system that would provide far more insight to my van’s power system than any normal person would ever think is possible.

It was April 23rd last year when I sketched out a block diagram of the van’s power system and started trying to implement the system in the Arduino with the help of my good friend’s Lars and Sam (who also helped me make my tethered balloon system a reality). In essence, the Arduino is a small microcontroller (super simple computer) that I am using to read the analog voltages from the 3 batteries. Since I wanted to be able to monitor the voltages in real-time, I added a Parallax 4x20 character LCD and a momentary contact switch to change the display views. Finally, in order to debug any problems with the electrical system, I wanted to understand what was happening to these various batteries over longer time periods. The simple option would have been to write down the 3 voltages on a regular basis and try to figure out what was happening, but in today’s age of technology, manual data logging just seems so outdated. So to accomplish the data logging, I added a microSD memory card to the Arduino with Sparkfun’s microSD shield. The coding of the Arduino was extremely simple apart from a bug in the LCD code I downloaded and an initially poor choice in the SD code that I used which was remedied with the newer code on the Sparkfun site.

Yup, it’s almost a year later but I have the battery monitor installed in my van now and it’s working! Rather than try to describe the system in detail here, I put together an in-depth video that walks through the whole system and shows off all the cool features. It’s not a short video, but if this is your kind of thing, you might actually enjoy it :-)

 

Finally, if you’re a geek who wants to take a look at what the battery voltages look like when the van is started and stopped, then this plot is for you.

Sure, I could have solved the problem the straightforward way, but then I never would have explored all these cool new worlds. By the way, I still have a smile on my face :-)