In planning for my upcoming EV project and weighing costs and capabilities, I've decided to go the DIY route on my controller as well as many other parts. One of the most impressive things I've noticed about the ReVolt controller is the way that basic hardware can be improved by dozens of features and repurposed for different tasks. However, there is currently no display run by the controller itself, only real time tracking via the (admittedly awesome) RTDexplorer software by Adam. I've seen multiple people on the P&S controller thread say they don't have a computer to spare for "controller control", and I myself want to take into account that even the people who do might not have a spare Windows install to put on one.
While the bootloader provides a great way to reprogram and update the controller without a laptop constantly in the car, there is still no good way to display volts/amps/precharge countdown/etc without a computer present. As I do computer troubleshooting and get donated used and half-broken laptops on a monthly basis, it's not a big obstacle for me, but there's got to be a solution that doesn't make you check your laptop while driving.
While ideally I'd do something with a PakTraker and an EVision 2, the P&S charger and controller would be phenomenal with some kind of cheap but powerful display system (also most people who DIY a controller don't have a grand to put aside just for counting how much money they're saving in MPG XD). So, the question is how we make a cheap display that won't substantially increase the cost of the controller or charger. And I don't just mean two multimeters strapped to the dash (cough) This is the "poor man's EVision" if you will.
While I was initially thinking of making some kind of LED dot matrix (pinball machine style display) that would have turned out to be just as expensive as building your own ReVolt from scratch. A better option that is still digital, software upgradable, and naturally circular-gauge friendly is a persistence of vision display. You've probably seen one before with the little fans you can get at football games that display a message on the blades as they spin. They are very
versatile as well as
cheap and DIY friendly so I think we can make a small addon board that communicates via CAN bus to the controller and charger.
Possible modes might be (for a 144v pack) 130-160v with a needle in between on one half and 0-500 amps on the other, with the needle changing color to red as it gets close to the danger zones. I don't know about the legality of swapping out the speedometer for a display, so I'm assuming we leave that alone. Other possible displays that could be added would be temperature, motor RPM, SOC (nice when charging too), precharge of the capacitors (zoooo0000OOOOOP FLASH goes the gauge!) as well as text displays like errors, estimated range, software variables, individual battery status, and other fun things I haven't thought of yet.
Going even further, with a simple button setup you could change controller settings or pull up a menu of presets without the need for a computer at all. Storing this data to a usb key or accessing it through a
business card web server is possible too. Let me know what you think and if you have any other displays you would like to see in an EV.