Porsche 914 EV

Rack cutting and welding complete

Michael — Sat, 28 Apr 2012 23:14:10 +0000

I finally finished all the cutting and welding on the battery rack. Now you can see the double deck layout around the motor. I just need to clean up some of the sharp edges and a couple bolt holes need to be hogged out a bit. After that I’ll give it a test fit in the car before breaking it down for paint.

More rack work

Michael — Tue, 24 Apr 2012 15:44:00 +0000

Continued work on the battery racks. Here is the main rack. I modified the outside frame to match the requirements for the thundersky batteries and I raised it 3″ from the main support. I cut out two cross members to allow batteries to be loaded into the lower rack. Now I just need to weld up the bottom rack

Battery Racks

Michael — Mon, 23 Apr 2012 03:53:33 +0000

Spent today working on designing and fabricating the battery racks. The new design will put 8 batteries on each side of the motor and 22 batteries above the motor. The racks are also now designed to allow for an 11″ motor to be installed. I could use a standard 11 or the interpolled 11. We’ll decide on that when the time comes but for now I wanted to fabricate the racks such that there is room to install the bigger motor. I’m using as much of the old rack as I can. The main frame is going to sit 3″ above the original to allow for the lower cells and the main frame is getting adjusted for the new cell size but the general layout will be similar. The lower racks will hang from the main rack. Below is a picture of the original rack from the engine compartment. I’ll take a picture of the new rack after it gets welded.

Condenser plan

Michael — Wed, 23 Nov 2011 00:18:28 +0000

Ok. Spent some time getting dimensions and started cutting steel for the ac installation. Here is a quick overview of what I plan to do. I’ll get a better video once I start putting the parts into the car.

Already on Plan B

Michael — Sun, 20 Nov 2011 20:20:12 +0000

Settling back in after the honeymoon took longer than anticipated. Who knew it would take so long to open gifts and write thank-you notes. The generosity from everyone was overwhelming. Thank you all for everything.

Now on to the EV update. I had done a quick layout of the batteries once they arrived and I confirmed the dimensions, but I kept ignoring the height. I knew these were taller, but I also knew that I was using some thin interconnects and did not think the extra height would be a problem. I thought wrong. Once I started detailing the layout and included height, I found that I needed about an inch (perhaps 3/4″) more height. The rack is constrained between the motor and the engine lid, so there was not even an inch to spare.

Plan B is perhaps a better way to go. I’m building three separate enclosures in the engine compartment. One on each side of the motor and one smaller one on top of the motor and the other two enclosures. By moving the cells alongside the motor I’ll be lowering the center of gravity which should help handling. The top cells will now be laying on their side which also lowers the cg for them as well. The same problem existed in the front batter box, so I’m moving it from the old gas tank compartment to the front trunk. this will lower the rack a few inches and move the weight forward, both of which should help to balance the car and lower the cg.

Moving the battery box to the front compartment also means that I’ll have to redesign the layout of the air conditioning system. I was going to build a system similar to what renegade hybrids does for 914 v8 radiator systems. It is a good setup, but does take up the entire front trunk. My new system will be similar to the way the factory did the A/C by cutting a hole in the floor of the trunk. I’ll be building a floor to capture the air between and force it through the condenser.

Now that the design has been redone, its time to get fabricating. I think I’ll start with the A/C system since it is going to go below the battery racks, and that will also force me to finish installing the system in the cabin. Right now it is just hanging by a few screws.

Charger

Michael — Thu, 06 Oct 2011 05:18:21 +0000

Something I forgot to mention in the list of things I’m changing about the car is that I am also updating the charger in the car. The original setup had a Russco charger, and I upgraded that to a Zivan charger, but both were only about 1500 watt chargers. I’d like to be able to charge faster, so I’m going to be installing a 10kW charger based on the open source charger offered by Electric Motor Works. Electric Motor Werks

Still No Progress

Michael — Mon, 26 Sep 2011 17:17:05 +0000

It has been an extremely busy year for me at work, and with my upcoming wedding, I’ve had little time to even think about the car let alone work on it. I knew when the batteries did not arrive as they were supposed to in September last year, I was going to have trouble working on the car. My slow period at work is from late september to about March, and when the batteries arrived after the new year, I knew I’d have trouble getting it done before I got busy. I also had a pool-house to build, and that project took priority over the Porsche last spring, so no progress on the Porsche. The pool-house is complete, I’m starting to slow down at work now, but nothing is going to happen until after the wedding and honeymoon, which we return from on Halloween. Hopefully I’ll have a productive November and December and have the car back on the road somewhere near New Years Eve. Look for postings to resume in November and I return to this project. It’s hard to believe the car has been down for so long. The other two times the batteries needed replacement, I think I let it sit for about 4-6 months and then the battery installation took only one day and it was back running. This years project is for more substantial as I’m upgrading nearly everything on the car, but still….Its been down since January 2010 and I pulled the batteries out in July 2010 when I ordered the Thundersky batteries. That means it will have been down 2 years once I get it going again.

No Progress

Michael — Fri, 15 Apr 2011 15:14:50 +0000

Its been a while since I posted, and there is a reason. I’ve not made any progress on the project. Between Taxes, Work and wedding planning I’ve not had time to do anything. I hope to make some progress on this in the next couple of weekends, and I’ll post any new progress.

Battery racks

Michael — Mon, 07 Mar 2011 14:18:01 +0000

Today I removed the hood and the trunk lid in an effort to start modifying and removing the battery racks. The rear battery rack is going to be very easy to modify. It seems I’ll need to remove about a quarter inch all the way around and move one piece of angle iron about half an inch. Ill end up with only two rows batteries in the back battery rack. This makes for a very simple layout to interconnect the batteries and easy to strap them together. The front battery rack is a little more difficult. The front battery track is a single string of batteries; however, the body is a little bit in the way cause these batteries are a little bit wider than the original batteries that were in the gas tank compartment. The original battery box configuration required me to actually hammer back some of the body work in order to clear the battery box and space available. With this new wider battery I have to hammer back some more but I think that the sheet metal was creased a little bit, and will not actually be able to bend it any further. I think I will probably have to cut sheet metal in order to get them to fit and still have room for the steering brackets that are in that same area where the sheet metal work needs to be done. Besides this one sheet metal requirement the front battery rack modification is quite easy and I won’t have to remove anything and reinstalling just have to do somebody work around the area where the battery racks too narrow. I’ll make this clearer in future posts when I show what I’m planning to do.

Battery Layout

Michael — Sun, 27 Feb 2011 17:48:58 +0000

Because I did not have the batteries in my possession, I never spent too much time trying to figure out the battery layout for the upgrade. I knew that most of the cells would fit into the large enclosure behind the seats where the original engine compartment was. The rest should fit in the front trunk or the gas tank area, or a combination of both. I really hoped that they would all fit into the gas tank area and that would leave the front trunk for the charger and the air conditioning equipment. I was not confident that this would happen and thought I’d have to put the charger and the ac equipment in the gas tank area where it is harder to access and then put the batteries in the front trunk. Worst case, I’d have batteries in both locations. As it turns out I got lucky. The batteries should fit nicely in just the motor compartment and the gas tank compartment. The layout is very easy with two rows in the motor compartment and one row in the gas tank. This should make the cabling very easy. Time to get some exacting measurements and start cutting the angle iron from the old lead acid rack and modify it to fit my new Thundersky’s.