Odds & Ends Part V

Well, it's been a very busy week and today was the first chance I've had to work on the Z3. Let's tally up what I did, shall we?

1. Finished the mount for the box that's going in the trunk. It will fit through the hole I've cut and into the cavity that was occupied by the fuel tank. Luckily, there was a mounting bracket welded to the chassis in very nearly the perfect spot for use to support the box. I cut a piece of light steel to bolt to it, and the box will simply rest on it, kind of wedged into place. I'll clamp it down on the front edge, and that will prevent it from moving at all.

2. I also cut a 2 inch hole in the back of the box. I will connect some ducting to it and it will do one, possibly two things. It will provide fresh air to the fans of the charger while it is running, and it may also be the conduit for the AC power line to the charger. I might just drill a separate hole for that so there is nothing in the tube obstructing air flow.

3. I figured out how I'm going to mount the power steering pump. I had decided that I would simply suspend it from the front battery box making use of the room there. Today I cut and fitted all the steel needed to support it. Next up for that is simply weld the steel up and then drill out a few holes so that I can mount it in place, easily removing it if necessary.

4. One of the biggest pieces of news this week is I've opted to scrap the idea of lead acid batteries in favor of Sky Energy LiFePo4 batteries. I'd come across a fabulous series of videos put together by a gentleman by the name of Jack Rickard, in which he talks about how best to treat LiFePo4 batteries. All fascinating stuff, but what really caught my attention was the price he mentioned that he paid for the batteries. When I started looking into the project a year and a half ago, a similar pack of Thunder Sky's would have run me over $20,000. Well they've come down substantially, making them much more economically viable. Jack was kind enough to answer some of my questions, and encourage me along. If you care to check out his project, you can see it here. First rate stuff!

The Sky Energy's will weigh in at 475 lbs, versus the 737 lbs that the lead acid I had intended to use would have weighed. In addition, if handled properly, they are rated to handle 3000 charge/discharge cycles. That amounts to approximately 150,000 miles, or for all practical purposes, the life of the car.

5. To that end, I need to redesign one of the battery boxes and the tray that holds it to accommodate the different shape of the batteries. Fortunately, there is no need to adjust any of the bracing that we'd welded up over the past few weeks. However, I will be able to reduce the weight of two of the trays used to hold the battery boxes. The two trays weigh in at about 32 lbs, and I should be able to drop that to about 10. Today I took all the necessary measurements and began cutting up the new lighter steel to hold it all.

That's all for now. Hopefully next week, I'll have more time for the project.