Though the main (rear) battery boxes haven't been mounted yet, we decided to work on the front battery box first. This box is a bit trickier than the rear boxes. The idea is to put 2 batteries where the radiator used to reside. Two batteries will fit in there but the problem is how to design it so that the batteries can be accessed (for watering) and so that you install and remove the batteries without disassembling half the car. Oh, and hopefully the batteries won't be so low that I would forever be worried about hitting the curb when I pull into a parking spot.
Option 1: Remove the sub-frame member that was originally between the engine and the radiator and put the box there. With this piece removed the battery box will easily fit in front of the electric motor and clear the upper support in the front of the engine compartment (where the hood latch resides). Upside: batteries can be dropped in from the top and access for watering will be easy. Downside: requires serious changes to the car's frame.
The pic below shows where the battery box would reside with this option (each cardboard box represents a battery). The cardboard boxes are higher than the hood-line because they are sitting on the sub-frame that would be removed.
Option 2: Put the box further forward (under the front upper support). Since we're further forward the batteries will have to be loaded into the box from the bottom. Upside: no changes to frame required. Downside: battery box will have to be very low because of the geometry of the hood latch.
Option 3: With a few minor modifications to the headlight and hood latch brackets and by trimming (but not removing) the sub-frame member in a few places, the box could be brought back slightly toward the motor and raised several inches. This seemed a good compromise.
The modifications required are:
1. Remove the raised portion of the stamping for the hood latch.
2. Trim the sub-frame in two spots to accommodate the rectangular battery box.
3. Remove a portion of the headlamp mounting bracket. Sounds scary, but the parts of the bracket where the headlamp is bolted will remain. It's pretty sturdy, and all the aiming functionality for the headlamp will still work. (picture shown further down in this entry)
So, how to attach the box to the car? There are very few flat surfaces in the engine compartment but after scratching our heads for a while we came up with a plan. We decided to weld 3 brackets in place to which the battery box will be hung from. A cross-brace running all the way across the engine compartment that will match up with the upper rear edge of the box, and two smaller brackets that will match up with the upper front edge of the box.
Here's the cross-brace, welded to vertical surfaces on either side of the engine compartment.