Now that the motor is mounted (see below), it was time to get serious about the batteries. 

I have known which battery modules I was going to run for awhile, but not exactly how I was going to mount them or position them in the car.  The battery modules themselves are 59Vdc lithium-ion "blocks" built by LG for the Chyrsler Pacifica Hybrid.  I chose these for a number of reasons, but mainly because being from a hybrid means they offer good power and the voltage/capacity of each block works out nicely to build to the voltage (360Vdc) and total energy on-board I'm targeting.  They are also readily available for a good price and since the vehicle itself has only been available since 2017, I can be sure that the modules I receive are relatively new and in good overall health.  

After considering a few different options, I elected to build an aluminum t-slot frame around the cell modules to keep them protected, under constant pressure, and make it easier to mount into the car with simple brackets.  The top and bottom face sheets are .125" 6061 series aluminum.  This will provide a nice, conductive interface for the integrated cooling sink plates on the bottom side of the module.  Since one set of boxes will be stacked, the fasteners are countersunk and I'll use the t-slot to tie the two boxes together structurally.  

I won't go into gruesome details over the BMS (Battery Management System), but I've selected a really nice system that will connect to measure each cell voltage and a series of 5 thermistors per module to monitor temperature.  The cell group monitoring units communicate up to a configurable master BMS unit over CANbus.  Here's a finished battery box, complete with a dual set of power terminals, 4-pin sealed CAN/12Vdc power connector, and removable handles to assist with loading into the car... 

I will need 4 of these battery boxes in the vehicle in a 2P2S (2 in parallel, then 2 in series) configuration.  Here's the position of battery #1 in the space between the rear wheel wells... (the towel was just to make it easier to slide around)

As of now, I think I need 1 in the trunk, 2 in the backseat area, and 1 under the hood to get a nice weight distribution.  Early indications are that I'm also going to need some stiffer spring rates in the rear!  Let me know if anyone out there has a good source!