Friday, November 20, 2015

A Pinch of This, A Dash of That

The Porsche's been home for going on three weeks now, and I'm getting accustomed to driving it. It's been a bit disconcerting to be out on the road with no instrumentation, though; no clue about the voltage, current consumption, temperatures, or state of charge. Only the speedometer from the classic gauge panel functioned, and rather poorly at that.

Pretty as the they are, the old gauges need to be replaced with something a bit more in keeping with electrifying nature of the car. I chose an Andromeda EVIC (Electric Vehicle Interface Controller) display that is custom designed for the GEVCU controller at the heart of my electric drive. This single display panel covers all of the useful driver information, save for speed.
The speedometer should be at least generally compatible with the digital nature of the EVIC, so an Intellitronix Digital GPS unit in a complementary blue hue was chosen. This speedo also has performance tracking and will measure 0-60, quarter mile, and top speed, along with a trip and cumulative odometer. Add turn signal, high beam, and precharge indicator lights and we have a full complement of function for the replacement dashboard.

To build the new dashboard, we start with ... a board! A scrap of 1/4" plywood will do nicely. I dug out my trusty 40 year old jig saw, got a new blade for it, and proceeded to ruin two blanks before I got to this point. I did cheat and got a 3 1/4" hole saw for the speedometer. Since the speedo needs a 3 3/8" opening, I also picked up a rotary rasp for my drill. New power tools will always warm my heart.

So here's a trial fit with most of the bits in place:

And here's the final fitting after many coats of flat black from a rattle can:

Yet another terminal board was needed to manage all of the connections. The large black box is the GPS controller for the speedometer. The relay turns on the brake lights under regenerative braking. That was actually the first thing I did on this dashboard project because with the aggressive regen produced by the Siemens motor, you can literally drive with only the power pedal. I don't want drivers behind me crawling up my tailpipe (sorry, no tailpipe) when I stop without signaling. The terminal board was installed under the dash in the space vacated by the gas engine Electronic Control Module.

The unit looks pretty nice when in place, but getting it there was a multi-day effort and wiring everything took hours of laying on my back with my feet in the air and squeezing my hands into very tight places with sharp edges.
All of it was worth the effort, because the effect is really quite stunning.

Now I need to figure out what's up with the Ah reading, but the rest of the info looks like it's accurate. I was a bit concerned about daytime visibility, but it appears to be a non-issue today in bright sunlight, and even is readable with sunglasses on - all good. Took the opportunity to remount the steering wheel in a more straight ahead position so I don't feel like I'm driving crabwise down the road. This has been a satisfying refinement of the car, next item will be to dampen the sound on the power brake vacuum pump.


  1. What firmware are you using to get the data out of the GEVCU and into the EVIC?

  2. Thanks! All I need to do is hook the GEVCU output to an OBD2->Bluetooth dongle,read and parse the data and drive the gauges in my Android app. I'll get right on that when I get home in February.

  3. I missed the Ah problem... 65535 is a magic computer number - the highest number which can be represented by an unsigned 16-bit binary number. Jack and/or Collin have a little bug left to squash.

    1. Thanks for the insight! I've recorded a video to send to Jack and Colin that shows that after a full charge reset, everything looks right, then it starts randomly showing off-the-wall numbers. Need to edit it down from real time to make it palatable.

    2. Here's a link to the video: