Battery Mount Construction

Tools and Materials

If you don't have access to a sheet metal shear or ban saw, you can use a cut-off wheel on a dremel or grinder to cut the sheet metal. If you don't have a sheet metal break, secure the sheet metal between two pieces of wood, and bend the metal by pressing it against a flat surface. Screw the two pieces of wood together to make sure the sheet metal does not shift during bending. Here is a site with a video that demonstrates this bending technique.

I purchased the aluminum sheet (alloy 1100) online from mcmaster.com. It cost $32.32 for a 24" x 24" sheet, which is more than twice what is needed for the mount. I bought extra just in case.

Construction

  1. I had to modify the original mount design slightly. I made it about a centimeter taller to account for the fact that the battery will be mounted on top of the humps in the trunk (see picture). The new CAD drawing is shown below. (All dimensions are in millimeters.)
    Humps on trunk floor which require a taller battery mount
    Redesigned taller battery mount CAD drawing
  2. I made the mount out of cardboard (again) to make sure I hadn't made any measuring mistakes. After test-fitting the cardboard piece on the battery, I drew the cutting/bending lines on the aluminum sheet.
    Cardboard mockup of new battery mount design
    Cutting and bending lines drawn out on aluminum sheet
  3. I used a sheet metal shear to cut out the aluminum rectangle that will become the battery mount.
    Rectangular piece of aluminum sheet that will become the battery mount
  4. Next, I used a ban saw to cut off the corners of the rectangular piece to match the shape of the mount.
    Corners of rectangular sheet cut out to form the basic shape of the mount
  5. I drilled four holes for the bolts that will hold the battery mount to the trunk floor using an 11/32 inch drill bit. I also drilled two holes on what will end up being the front of the mount. Since the polarity of the terminals is marked behind where I wanted to have this front plate, I decided to drill holes so you can still see the polarity.
    Mounting and polarity holes drilled in aluminum sheet
  6. Then, I bent the aluminum with a sheet metal break. I bent the front and back tabs first and then the sides of the mount.
    Mount after initial bending
  7. I couldn't get sharp bends on the edges of the two sides. The back tab on the mount got in the way and did not allow me to bend the full 90 degrees using the sheat metal break. I was able to bend the sides about 45 degrees and then had to bend the rest of the way by hand. As a result, the sides did not have sharp bends at first. To reduce the curvature, I secured the mount in a vice, placed a small block of wood against the side of the mount (sticking out of the vice), and hit it with a hammer to get a sharper bend. You can see the difference in the last few pictures.
  8. After finishing with the bending, I sanded the mount to remove the scratches in the aluminum. I started with 120-grit paper, then went to 320-grit, and finished it off with 2500-grit sandpaper (Meguiar's Unigrit brand). It would have been a lot easier if I used an intermediate paper between 320 and 2500 (possibly 1000), but I did not have any so I had to spend a longer time sanding with the 2500-grit.
    120-grit, 320-grit, and 2500-grit sandpaper used for sanding battery mount
    Mount after sanding with 120-grit paper
    Mount after sanding with 320-grit paper
    Mount after sanding with 2500-grit paper
  9. I still have some sanding to do and then maybe polishing, but here's what it looks like for now. I should be able to install it next weekend.
    Battery mount completed
    Test-fitting the battery mount on the Braille battery

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