Specs:

• Total Budget ~$25000

• Tesla Model S P100D Large Drive Unit 2014

• 54kwh 3x Chevy Spark EV 2016 LG Chem gen 2 battery packs 

• CHAdeMO DC quick charging support

• Factory Five 818C kit car

• Subaru WRX 2002 donor car

• Active Battery Thermal Management System

  • AC system for sub-ambient cooling

Revisions:

• Since this project is ongoing, all specs are subject to change. I hope to document the different paths I've taken so far here.

  • BMS revision 1: since I'm monitoring a total of 288 cells, I needed to revise the BMS system. I decided to build my own based on ZEVA open source BMS project. After modifying layout for easily soarable parts, I built and wrote code in microchip studios (BMS uses a Atmega64m1) to remap the CAN protocol to allow for more versatility in monitoring larger packs. Ultimately I had problems reading reliable voltages from the LTC6802-2 BMS IC as I was getting them from somewhat dodgy suppliers on eBay. I plan to revisit them with LTC6803-2 from digikey as they are pin compatible but I need to write CRC code since they rely on a checksum to read from regs.

  • BMS revision 2: I'm now designing a CAN controller based on the TMS570 Hercules safety microcontrollers. HALcogen and CCS have been challenging for me to learn since I have never programmed before this but I am making exciting progress (reading cell voltages after unpacking decoded chevy volt bms modules). I am using a total of 3 Chevy Volt Gen 1 BMS modules and will use 3 separate CAN networks of the 4 on the TMS570LC43 MCU to avoid repeat IDs. The last bus will be 500k and interface with everything else on the car. This is taking significant development time and has slowed me down quite a bit.

  • BMS revision 3: I completely changed the battery pack configuration in the car. I now am using a full repacked battery from a Chevy BOLT EV. This means that the parallel groups total to only one string and I can use a single high BMS to control it all. I was also able to negotiate for an Orion BMS Gen 1 108s used and thus I went this route. Both BMSs revisions above where successful but in the interest of saving money (I saved a lot of money moving to the bolt pack) I was able to get a more tested and robust system.  

Info:

• It's currently in the works and will not be finished for a few years at a minimum.  Since I go to school on the east coast, I can't work on it nearly as much as I would like. I'm anticipating a top speed of 140 mph and a range of 150-180 miles. Quick charging will allow from 0-Full in 45 minutes.

• I'll make sure to update pictures on here once and awhile.