Tuesday, July 8, 2008

Bolting Together the Front Battery Rack

I'm taking a different strategy from many EV installations in the hopes that people can more easily put together a kit for the Civic at home. Most folks weld together battery racks and then bolt them into the car (or sometimes weld them in). This strategy uses beefy angle iron pieces and 3/8" grade-8 bolts with nylock nuts to hold things together. I'll revisit whether this strategy is a good one or not after trying it out. Worst case, I take the bolted together frames and weld them.

Here are the main supports for the front battery rack and the rear trunk battery rack. We have two 10" long pieces of 2" angle iron for the front rack and two 18" long pieces of 1.5" square tubing (1/8" walls) to go in the trunk.

In order to bolt the main supports to the frame, we need to drill holes in them. Here I'm drilling 3/8" holes in 5/8" from the end of each square tube. I found that clamping the metal stock to the furniture dolly worked quite well for drilling since I could put my knees on the padded areas and there were several places to clamp onto.

Keep in mind when drilling holes that it's best to drill a "pilot" hole about 1/8" in diameter and then use the larger drill (3/8" in this example) to follow the pilot hole. Hole placement will be much more accurate and the large drill won't skip all over the place. Don't forget to wear your eye protection as well. Little bits of metal fly everywhere when drilling.

Hmm... It looks like the rattling from the drill shook the nuts off the furniture dolly casters! I found several nuts and washers lying on the floor that had nothing to do with the Civic and this is where they were coming from. I re-assembled the dolly and cranked down the caster mounting nuts tightly.

Remember the two 10" pieces of 2" angle iron? Here is the first one installed using the bolts from the towing bracket. The center of the holes are 15 mm from the top edge of the angle iron. The first hole is 20 mm in from the front end and the second hole is an additional 30 mm back. I only had english drills, so drilling 13/32" holes seemed to work fine.

Here's the main support bar installed on the driver's side tow-hook bolts. The hole placement is the same for the passenger side, but just mirrored.

With the two main supports in, I measured between the edges and took off a little for the curve at the corner of the angle iron. For this vehicle, cutting two 1.5" angle iron pieces 34 3/4" long worked quite well. In order to rotate the front angle iron piece into place, I had to remove the rear tow hook bolt.

Here I'm using the foam-core batteries to make sure I have enough clearance for the clutch slave cylinder. Things look pretty good.

The next step was to remove the 1.5" angle iron and drill 3/8" holes in each end. The holes were 1" from the end of each bar and 3/4" in from the edge (pretty much centered).

After putting the 1.5" horizontal angle iron bars back in, I pushed the front one as far forward into the front grille as possible and clamped down the ends to the main support (shown in picture) with small clamps. With the piece clamped in place, I could use a 3/8" drill to make a hole through the top piece into the main support. After this a 3/8" grade-8 bolt (3/4" long) with nylock nut was added to hold things together. I did this to both ends of the front bar.

After the front bar was bolted in, I measured 6 15/16" inside distance from the front bar to place the rear horizontal bar in and clamp that down with the small clamps. After drilling 3/8" holes and adding bolts with nylock nuts, the front rack base was complete.

Here's the completed front rack base. Keep in mind that this is only held in by two bolts on each end from the towing brackets. I plan to add vertical steel bars on each side to the extra 3" of angle iron protruding upwards in the picture. This is a good start, though. The foam-core batteries fit well and give good clearance to the clutch slave cylinder.

Again, after bolting this whole thing together, I'll revisit whether using heavy duty bolts and supports will be sufficient compared with welding. The intent is to make this kit easy to create and install.


Rick said...

I am so looking forward to the progress of this blog. Your Porsche 914 blog inspired me to want to do my own Porsche 914 EV... until I got to the end! Oh well... I'd much rather have an EV that I wouldn't feel bad about driving in the dead of winter through the salt-laden streets. I'm thinking I might even get myself a Civic and follow along!

Best of luck, and I can't wait until this one is finished!

Unknown said...

When's your Estimated time of completion? Keep up the good work!

TimK said...

Let's see... I get the motor, lugs and covers at the beginning of August. The controller and integrator will probably show up mid-August. The charger will probably be mid-September. I'm guessing end of September for my own conversion. Then there's the writing of the open-source manual with revisions, so that will probably happen through the winter. All current info is posted on the GoogleGroup, so you can watch the progress. Tim