Zach’s Electric Diablo

I know it sounds like an excuse, but the house remodel is taking all my time.  Check out these videos:

I promise… one of these days I’ll make time to work on the car.

Today I transported my car (via trailer) to my house.  Now it should be much easier for me to find time to work on it.

It’s been a busy month and I haven’t had a single moment to work on the car.  I’ve got a couple more weeks of craziness and things should slow down enough to give me my weekly work session again.  After being a consultant for past few years, I finally decided to get a “real” job.  I’m now building underwater robots and submarines.  It’s really exciting to start working in a field that is so different from anything I’ve done before.   I’m learning how to make technology work in very harsh environments.  Some of these skills will definitely help in making the car more robust.

Lately, every time I work on my car, I forget to bring my camera.  So, there are no recent pictures. Sorry…

Even though I can’t prove it with pictures, I’ve been making some major steps the past few weeks.  The big one is that the body is now mounted.   YEAH!!!  It took eight tubes of 3m 5200 adhesive and a week to cure, but it is permanently on there.  I’ll try to remember the camera this weekend.

I’m now onto the daunting task of the doors.  They truly define that “Lamborghini style” and they need to work smoothly.  So, I am taking some extra time to plan my attack.  The doors end up weighing around 250Lbs and are supported by a single hinge just a few inches wide.   So, everything has to be very rigid.

My friend Vincent is a true professional when it comes to composites. He has been very helpful with all my bodywork and fiberglass questions (e.g. What’s the best way to bond X to Y?). When I told him my plan about bonding my shell to the chassis with urethane caulking, he had lots of suggestions. The first one was to use 3M 5200. It’s typically used for marine applications, but it is incredibly strong and stays flexible.

His next suggestion was to “bog” the mating surface between the shell and the chassis (I learned that in the fiberglass realm, the term “bog” refers to a resin filler that fills gaps between materials). We started out by using double sided tape as a spacer. Then we layered pieces of packing tape over the double sided tape. The double sided tape creates a space for the caulking, the packing tape helps release the bog.

We also used some “magic” mold release liquid on the packing tape as an extra layer of insurance.

After that, we glued some regular fiberglass mesh to the chassis using 3m 77 spray adhesive. Then we mixed up the bog. The bog was a mixture of two part fairing compound (similar to Bondo, but much better) and short fiberglass strands. This made the bog quite stiff and less likely to drip all over the place. We spread the bog onto the fiberglass mesh, then placed the shell onto the chassis. We clamped it in place to get everything level.

After 24 hours, we popped off the body. The bog stuck to the shell very nicely and released from the chassis with almost no effort. This is the result:

Now I just need to clean up the edges of the bog and then prep both surfaces for the 5200. Next week we should have the shell mounted.

Last night, I soldered up the first section of the BMS board.  On the top side of the PCB there’s a processor, an FTDI USB bridge chip, a bunch of fuses and a handful of passive components:

On the bottom of the board, I soldered on four (out of the 50) shunt resistors:

I am mounting the shunt resistors away from the board to allow for better air flow.  They get pretty warm with 2.5amps flowing through them.

So far, the initial tests look good.  I am able to program the processor, flash LEDs and send data over USB.  Next, I need to test communications to the LTC6802.  In order to do this, I need to wire it up to some batteries.  I’ve got some nice connectors on order to make this job easier and more fool-proof.  They should be here in a few days.

I also spent a little time welding up some brackets to hold the roll cage in place.  I’ll snap some pics of these next time I am down in the shop.

Today, I put a little more work into the heater setup. I found (what other EV’ers have used) a couple inexpensive ceramic heaters.

I’ve mounted two of the elements, in parallel, across the face of the modified heater core.

I’ve glued them in place using high temperature RTV gasket compound. I’ll test it out once the RTV fully cures.

This week I also got a new keyboard for the car (typing on the touch screen is a pain), a fire extinguisher (safety FIRST!), a new slave clutch cylinder (my old one was leaking) and an ultrasonic parking sensor kit which I will mount in the rear bumper.

Last, but not least, I put the finishing touches on BMS V2.0. I’ll send it off for fab this week.

My seat is now bolted to the floor and the racing harness is installed.

I also installed the Mac mini, 12v power supply and an LCD screen (the LCD mount is temporary until I mount the dash). This setup will be helpful during testing to display battery status and speed information.

Now that I am starting to accumulate the 12v devices, I thought it was about time to officially wire up the DC to DC converter. It takes the pack voltage and charges the 12v lead acid accessory battery.

While waiting for my axle to come back, I decided to spend some time cleaning up the wiring. I replaced the short pieces of 2-0 wire with some custom copper jumpers (like the ones that came with the batteries.) for the short connection from the fuse to the shunt and from the shunt to the relay.

I also machined some aluminum offset connectors so that the cables can easily exit the battery box.

I wired up my Iota 55 DC-DC for the first time. It spit out 13.6v just like it’s supposed to.

I also spent some time making a short term to-do list:

1. Re-install the axle and do a proper test-drive (with video documenation)
2. Build harness for auxiliary 12v battery.
3. Buy and install seatbelts/harnesses
   (a coworker showed me his 6-point racing harness. Very cool. Very expensive.)
4. Bolt down the driver’s seat
5. Build the 12v relay panel
6. Install Mac Mini and power supply
   (mainly this is designing a mount for the Mini)
7. Start dashboard layout
8. Revise the BMS design
9. Design safety cover for the high voltage electronics
10. Install the heater/AC unit
11. Figure out motor-to-AC compressor system.
12. Weld the firewall closed
    (there is a big hole where the fuel cell was supposed to be mounter)
13. Weld / reinforce the the center console area.
    (I cut out a big portion of the center console to make it thinner. It was wide where the fuel cell sat)
14. Mount the body on the chassis (this is mainly building the mounting points for the roll cage)

I’m sending the axle back to the guy that made them.  His name is Frank and he runs http://driveshaftshop.com/

He is going to inspect the axle for damage and reassemble it.  He has given me great customer service and I would definately buy axles from him again.