Schematics Page 3: High-Voltage Connections

Battery Pack Arrangement

This build uses 6 5.3kWh Tesla battery modules (a very popular choice for a lot of these DIY EV builds). I've distributed them around the car in 4 boxes:

Box A: holds 1 module
Box B: holds 2 modules
Box C: holds 1 module
Box D: holds 2 modules

They are distributed around the car in this fashion:

subaru baja side view

And are wired A->B->C->D (obviously).

To manage all of the high-voltage connections in the engine bay, I also ended up purchasing a JIB-HV box from FlashDrive motors as well. It packages a battery isolation switch, the main contactor, and wiring for the on-board charger and interfaces to the Hyper X1 inverter, which is super-handy for my build.

the JIB HV box

Also, I really do need to tip my hat to FlashDrive. James Fleischman, the owner, has been super helpful to me during this whole build and I wouldn't have gotten anywhere near this far without his help and expertise.

BMS Connector Wiring

Each battery module also has a connector for the BMS which looks like this when looking at the connector on the battery module itself:

Battery module connector pins

The Vero BMS connects to the Tesla battery modules in a ring topology (and I suppose this is how a lot of BMSes work?), as this diagram from their setup manual shows:

Vero BMS wiring diagram

Because of this, I figured that each battery box should have a "BMS In" port and a "BMS out" port, and to allow the BMS wires to pass through from outside to inside of the boxes, I decided to install a pair of 4-pin Deutsch connectors on each box. What was stupid of me was to not use different receptacles for the "In" port vs the "Out" port. Both "In" and "Out" used female receptacles, so I needed to be careful to label each port so I didn't accidentally wire two inputs together or two outputs together. (which is something that I naturally did when wiring up these boxes for the first time).

Many times, I had to try to remind myself how the hell I had mapped the pins. If I didn't know how I'd done this, I am going to need to tear into the boxes themselves and trace out the pins myself, and now that these boxes are mounted, that is going to be such a huge pain in the ass, especially with box D, so here is how every box is wired: