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Discussion Starter · #42 ·
That's great ,
Maybe I missed out , but , how much modules will you put in ? , all 16? to get proper voltage..
We are starting with 14 modules, which is the old Model S 60 configuration. It will be very tight getting them in. We were able to get 14 foam models under the hood while accounting for just enough between them for connections and mounting. But it was still best-case, and our brake booster - while smaller than the original- will still eat up a bit of that space that we tested with.

So we may wind up with 2 modules in the rear (above the drive unit where I wanted that cool plexiglass section to be). We could put one under the rear seats if we had to, but I don't want to have them spread out under every knock and cranny :)

Bottom line is, 14 modules to get our minimum voltage, then if we do wind up better off than we think we will certainly add 2 more to bump up kWh.
 

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Discussion Starter · #44 · (Edited)
There has been a lot of progress on the car. Most of it restoration related, and I will spare you those details. Here is the progress on the EV conversion:

First, we wrapped up our work on the suspension subframe. As was discussed earlier in this thread the BMW uses the differential rear mount as a third point of attaching the subframe. My idea was to replicate this "T" by extending forward into the tranny tunnel. We fabricated an arm and used a Chevy motor mount up front. Here are a couple of photos (turned sideways since apparently that's how attachments show up in this forum if I don't bother to upload them elsewhere first).

We are using the 057 Tesla controller for the Tesla drive unit, which I have discussed some here. Jason has done a remarkable job with this unit. I know some here are dubious of 057, but I have had an incredible experience with his support. He has gone the extra mile for me in a number of ways.

He even shipped me a prototype of his forthcoming precharge unit along with a couple of Tesla contactors. This unit does an great job of automating the capacitor precharge sequence.

We've been spinning the Tesla unit for a couple of weeks now, but we finally received our axles. We shipped a pair of Tesla inners to Lee at The Driveshaft shop who does amazing work machining and welding a flange to the inners. I also had them make a new pair of axles to handle the additional torque and horsepower.

So things are moving along pretty nicely.

I can't seem to be able to embed a YouTube video here any longer either- I just checked and the videos that worked great earlier in this thread no longer work. But here's a link if you care to watch! https://youtu.be/lShbH-DR42s

I don't mean to be a complainer, but this forum really does seem like it's running on 1996 tech :)
 

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Discussion Starter · #46 · (Edited)
Re: 1974 BMW CSE

I haven't posted here for quite a while. It's been a very busy year with work. We have taken the car a long long way since I last posted. While I have been pasting my blog posts here, I will save you all the storytelling of the blog, and just post the parts that might be of interest. I have loved the comments back from this group so I certainly welcome any additional thoughts as we get close to driving our car. I think it was last Spring when I last posted, so here is what we have done since then!

Steering

The original steering setup of the coupe, like the inline six motor is an important part of the E9 racing heritage. It was a conflict to rip it out, but for our particular goals, it needed to happen. We need to fit a lot of Tesla battery modules under the hood, and the large steering box takes up a lot of space. The steering column, box and all that iron linkage is also incredibly heavy. We opted to convert to a modern hydraulic power steering rack which is lightweight, efficient, and tucks in tight and low under the battery modules.

Why Not Electric Power Steering?

A lot of folks have asked me why we are not going with an electric power steering system. We deliberated a lot about this, as it is the future of power steering, and completely in line with our EV ethos. There are two reasons we opted against:

1- Electric racks have traditionally been terrible for driving experience in terms of their feel and input from the road. Only in very recent years have manufacturers made vast improvements in that area. The best systems also require constant communication with the computer which is receiving a lot of data about car speed, accelerometer, turn degree, steering wheel rotation and more in order to give proper assistance while retaining a desirable amount of road feedback. I went pretty far down this road before deciding that it was not going to be worth the effort - not when a good hydraulic steering rack feels great right out of the box.

2- We plan to use a hydro-boost brake system. Remember, we have no engine to produce vacuum. More importantly, vacuum systems are very large under the hood). Since hydro-boost systems run on a power steering pump, it made perfect sense to install a 12 volt power steering pump (from a Mini or Volvo) which will nicely power our brake and steering systems in a clean loop.

I can see a time in the near future when there will be good options for electric steering and brake boost systems for conversions like this. Maybe my next car…

We started with a goal to use nothing but BMW or Tesla parts for this project. However, when it came to the steering rack we had to deviate. BMW’s modern racks are front-steer (the rack sits in front of the wheels) and our coupe is rear-steer. We prefer the car to follow the most widely-recognized standard of turn the steering wheel to the left and the car goes left. Since we did not want to completely modify our car to front-steer, we opted for another German-engineered rack from a car of similar weight and size. The Volkswagen MK3 GTI VR6 rack fit the bill. Even then we had to shorten the tie-rods quite a bit. It’s crazy how small BMW’s original “big coupe" is compared to modern "compact” cars.


We started by cutting away a handful of motor and steering mounts from our subframe. Cutting away stuff is usually my favorite part of the project. Brett here is having a dandy time with the plasma torch.


We test fitted our new rack in position using a series of construction clamps. They did the job just fine.


We cut some funny shaped sections of steel to make some mounts…


Then we got the rack tack welded in. Things look good in there. Nice and compact and low in the compartment. We will finish the welding and clean everything up after a bit more testing.

The “Everything You Touch” Motto


A few months ago I was chatting with a friend about what should be original what should be modern on the car. Clearly our Tesla unit is modern, but that doesn’t affect how the car looks inside or out. He made a comment that stuck with me: “Everything you touch should be modern”. While I would love to take credit for the motto, we have really continued down that path. The steering column falls into that category.

We decided to fit a BMW E46 (1997-2006 3 Series) steering column for a few reasons. It weighs half of our original column, but it also gives us a host of features without going over the top with complexities (no electric memory tilt, etc) We get a modern turn signal lever with lane-change soft touch, a wiper lever with modern variable intermittent control. The computer button on the end of the turn signal lever can be useful to us as well. Most of all, we get telescoping and tilt steering. These items directly fall into our “Everything You Touch” motto.


Our E46 steering column is fitted into the dash with a bit of customization to the mounting areas.


Here’s our Frankenstein steering linkage. Starts as a BMW on top, then mates to VW linkage on bottom to connect to the steering rack.


A lot of cleanup yet to be done on the firewall, but the linkage is tidy and works wonderfully.

Finally, we have a working steering system that should feel great on the road, weighs about half of the original setup, and leaves more room for batteries. That there is a win-win-win.

I can't get the embedded YouTube function to work- if anyone has some advice I'd love to hear it! But here's a link to a video of the steering functioning:

https://youtu.be/ZnieRFItVc4

Cheers!

Paul
 

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Discussion Starter · #47 ·
Re: 1974 BMW CSE

I've mentioned more than once that our car had not gotten along very well with snow and rain in the past. The more we dig into the structure, the more we think that she may have spent considerable time on the bottom of a lake.

Our coupe is no special case, mind you. Rust prevention was just not given much thought until later in the 1970s. I have talked to long-time owners who had to rebuild inner fenders, floors and rocker panels in the late 1980s - when their car was only 15 years old. Our car spent its first twenty years in Berlin where it saw plenty of weather, major rust is to be expected.

There are multiple layers of steel forming the coupe’s rockers. Since this was my first E9, we honestly didn’t know how many layers there should be, and the shape they should all take. Tyler performed a lot of archeological digging on each of the four corners to discover what the rockers should actually look like. We also received a lot of help and photos from the great community at e9coupe.com. We could have cut them entirely out and purchased/installed completely new rockers, but there was plenty of good and original metal behind all that rust worth preserving. We thought it more gratifying to leave the good and fabricate only the rotted sections of each layer.

Here’s a shot of our driver side rockers looking from the rear tire forward. It’s not a pretty sight.



We Can Rebuild It


We began by carefully cutting the rot out layer by layer back to good steel. This photo shows what was left once the rot was removed.


Tyler then fabricated a section to rebuild the first layer.


We then started fabricating the next layers. We also rebuilt the lift point pockets.


More fabricating and more welding…

Surely the front wasn’t as bad…


The front was no better than the rear. Rust is one thing, but some driveway rust repair had been done at some point confusing how things should actually assemble. This required Tyler to do some real digging on both driver and passenger sides to recreate how the layers were supposed to look.


Figuring out what was supposed to be going on was the biggest challenge.


We are not against buying sections of metal when it makes sense. More than happy to not fabricate this complicated little guy.

Capping it all off

With the structural layers all complete we can finally cap it all off. We went our own direction here, opting for a custom cap with tight gaps to the fender and quarter panel which we welded in place. This provides a very clean and tidy look.



Meanwhile, we were floored.

While all this was going on we were also fixing up the floors. The coupe had Fred Flintstone floors on all four positions. We purchased new floors for this. The rears were perfectly stamped and shaped for the car, but the fronts seemed to be a generic “Automobile/Front” floor pans. The stamp was directly over the frame rail. So we cut off the side, pushing the stamp to it’s proper place between the rail and the rocker. We then extended the inside to the transmission tunnel and curved all the edges to mate to the car. A bit of work, but in the end it looks as good as the floors I saw BMW Classics doing in Munich last winter.



Cheers!

Paul
 

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Discussion Starter · #48 ·
Re: 1974 BMW CSE

Just Spinning Our Wheels

We explored various methods to mate the output of the Tesla to our BMW hubs. We couldn’t modify and reuse the original BMW axles as they would twist like paper straws under the high torque of the Tesla unit.

We turned to The Driveshaft Shop in North Carolina whose slogan is “We specialize in the impossible”, and for good reason. We sent them the inner portions of a pair of Tesla axles and a host of measurements. A few weeks later a beautiful new pair of Frankenstein axles showed up and bolted right in. The craftsmanship is stunning.


Beautifully crafted axles. They are completely new but the far right section which was out of a Tesla. The left end bolts to the BMW wheel hub and the right spindled end inserts into the Tesla drive unit.

Control System

On the rear deck of the car we temporarily set up all the gear needed to run the Tesla drive unit.

To communicate with the Tesla unit are using the 057 Technologies control system. We believe that Jason and his team have put together the most elegant and capable unit. I evaluated the handful of other control systems before landing on the 057. I like that each 057 is directly paired to a particular Tesla drive unit with matching firmware. I believe that it is offering tighter, closer to native control of the Tesla unit than the others. This is, however, only my opinion based on my particular research and understanding. There are plenty of 057 critics who don’t like their direct pairing as it prevents you from purchasing the control unit separately (to control a Tesla drive unit you purchased elsewhere). As an Apple guy, I have usually preferred the power of closed systems, but that is a whole other argument. This is simply a matter of preference.

To further beat a dead horse, there is another strong reason I selected the 057 unit. Their device is a small box you hide inside the car and communicate with it any way you like. You can use simple buttons on your dashboard, or talk to it through a touchscreen that you can design as you like. All other controllers are touchscreen systems that you must install into your dash. They do not allow you to edit the look and feel of that touchscreen. As you can see from my early mockups of the interior, I have strong ideas about how I want the inside of the car to look and feel. I didn’t want to simply bolt on a generic looking touchscreen into the dash.


Our Jetson’s-inspired control panel, used for our early testing.


Here is our collection of control equipment L-R. (offscreen) our vintage control panel, 12v battery to power the three computers, 057 Tesla controller, precharge system including control board, resistor, and high voltage contractors, and accelerator pedal.

We (Almost) Have Lift-Off!

I must mention the days of troubleshooting once everything was all connected. Not to get overly technical, but there are a lot of variables in place and all of them have to go perfectly right for success. High-voltage from the Tesla battery modules, 12 volts from our car battery, the precharge system to properly ramp up high voltage into the Tesla inverter (part of the drive unit), the control module, accelerator pedal, axles, lubrication and more.

We had issues not with some but with most of these things. Things as tiny as a bent pin inside the accelerator pedal, resulting in no communication to the unit. Both Tesla and 057 have safety mechanisms in place. If something reports an error, things generally don’t spin. We got pretty comfortable reading error codes from the Tesla unit on our laptop.

This process itself was incredibly gratifying. Yes, we were frustrated and just wanted to see the wheels spin. But it delivered an unexpected gift of added respect for all the years Tesla (and all of the other) engineers spent developing and refining these automotive EV systems. To think that this should be easy is crazy. But equally crazy is that because of their work a guy like me can buy a bunch of parts from various sources and build such a classic electric sports car.

After all of the dreaming, engineering, fabricating and troubleshooting, we were finally able to experience the best day ever on this project and there were cheers all around.

Here’s a short little video:



The day finally came when we were able to spin the wheels on the coupe for the first time.

Cheers,

Paul
 

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Re: 1974 BMW CSE

I can't get the embedded YouTube function to work- if anyone has some advice I'd love to hear it!
The forums embedded YouTube player - what you get with the YouTube icon in the graphic editor or the YOUTUBE commands - use Adobe Flash. That works for some users, but is blocked by some browser and operating system combinations, leaving only a big non-functional blank.

The straightforward links to YouTube videos work fine, so don't worry about (or try to use) the embedded player.
 

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Re: 1974 BMW CSE

We explored various methods to mate the output of the Tesla to our BMW hubs. We couldn’t modify and reuse the original BMW axles as they would twist like paper straws under the high torque of the Tesla unit.

We turned to The Driveshaft Shop in North Carolina whose slogan is “We specialize in the impossible”, and for good reason. We sent them the inner portions of a pair of Tesla axles and a host of measurements. A few weeks later a beautiful new pair of Frankenstein axles showed up and bolted right in. The craftsmanship is stunning.


Beautifully crafted axles. They are completely new but the far right section which was out of a Tesla. The left end bolts to the BMW wheel hub and the right spindled end inserts into the Tesla drive unit.
Okay, the inboard stub is Tesla, but not the inboard CV? Do you know what CV joints were used? I wonder if they might be the very popular Porsche 930 type, a bolt-to-flange style for which a variety of flanges are available. What "level" in their axle system did you choose?
 

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Discussion Starter · #52 ·
Re: 1974 BMW CSE

Okay, the inboard stub is Tesla, but not the inboard CV? Do you know what CV joints were used? I wonder if they might be the very popular Porsche 930 type, a bolt-to-flange style for which a variety of flanges are available. What "level" in their axle system did you choose?
Sorry Brian I actually don't know where we landed there. After a couple conversations with Lee on the phone he recommended a setup based on my car/drive unit configuration. I know we discussed the 485HP that my unit would be equivalent to, along with the high torque. Axles and CVs aren't my universe, so I felt that I didn't have anything to contribute to the conversation.

From my invoice:

"108mm Axle with 28 spline bar and 108mm CV's on both ends with Chromoly internals (Made with 14-1/4" 28/28 Spline Axle Bar)
108mm Head for welding to CV's and Driveshaft Trans yokes 1018 or 1020 steel
Machine / Weld Tesla Inner to 108 Flanges"
 

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Re: 1974 BMW CSE

From my invoice:

"108mm Axle with 28 spline bar and 108mm CV's on both ends with Chromoly internals (Made with 14-1/4" 28/28 Spline Axle Bar)
108mm Head for welding to CV's and Driveshaft Trans yokes 1018 or 1020 steel
Machine / Weld Tesla Inner to 108 Flanges"
Thanks :)

Yes, it looks like the joints are the 108 mm diameter 6-bolt type as used widely in racing and modified applications. I think the 108 mm size is larger than what Porsche used for the 930 (1975-1989 911 Turbo, and the source of upgraded parts for many hot VWs), which is good because as impressive as that car was at the time, the Tesla drive unit can put out more torque. The 108 mm bits are Formula 1 worthy stuff (in the right grade, and with the high-speed boots).

The "bar" is the shaft between inner and outer joints, using the 28-count spline most common for these joints, regardless of what either the Tesla or the BMW would have had. The length of the bar is to suit the dimensions from the car and the width of the drive unit.

The Tesla stubs were machined off and welded to flanges, which in turn are bolted to the inner CVs.

The description doesn't explain what was done on the outboard end to mate the bolt pattern of the outer 108 mm CV body (six M10 bolts on a 94 mm diameter circle) to the BMW's stub axle. The CSE appears to use this style of CV joint; it seems unlikely to me that it would be the same size, but presumably this axle specialist has the sizing right.
 

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Discussion Starter · #54 ·
Re: 1974 BMW CSE

Thanks :)

The description doesn't explain what was done on the outboard end to mate the bolt pattern of the outer 108 mm CV body (six M10 bolts on a 94 mm diameter circle) to the BMW's stub axle. The CSE appears to use this style of CV joint; it seems unlikely to me that it would be the same size, but presumably this axle specialist has the sizing right.
Yes, that I all understood, it was your question of the CV that I really didn't know. The 94/108mm is the stock BMW hub. They used the 108 at the inner as well to match them up.

Clearly the CSL racing variant of the coupe that dominated in the early 70's was a beast. I assume they shared the same hubs as the street cars like mine, fortunately for me. I actually asked Lee about that while I was sending him all my measurements: "Will the hubs be a weak link" and the answer was no.

Thanks again Brian, you sure know your driveline:) That's what I learned about this group early... I assumed it would be full of "EV" folks more than car historians and enthusiasts, but I have been proven wrong many times. There's a great diversity of skills here across all aspects of autos, old and new.
 

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Re: 1974 BMW CSE

Yes, that I all understood, it was your question of the CV that I really didn't know. The 94/108mm is the stock BMW hub. They used the 108 at the inner as well to match them up.
The breakdown was as much an exercise in understanding the setup for me and getting confirmation, as information for anyone else :)

After posting my comment I found the GKN Löbro website with their catalog, which has an excellent description of the various axle configurations which their parts support and which they can supply. In their illustrated list of axle assembly types, this is a Type 102, the first one shown... plus that custom Tesla adapter as a (in GKN's terms) "connecting device".

It's fortunate that the BMW uses such a common CV joint type and size, making this straightforward solution possible.

I'm more accustomed to front wheel drive vehicles, which have a non-plunging high-angle CV joint on the outer end and a tripod joint for high plunge on the inboard end, and rarely have a bolted flange anywhere in the shaft assembly; rear wheel drive like this tends to use a plunging low-angle joint at each end, and - I now realize - often have four bolted flange connections in each shaft.

Clearly the CSL racing variant of the coupe that dominated in the early 70's was a beast. I assume they shared the same hubs as the street cars like mine, fortunately for me. I actually asked Lee about that while I was sending him all my measurements: "Will the hubs be a weak link" and the answer was no.
That is a nice feature. It turns out that according to the GKN Löbro catalog the 108 mm joint is "size 15", only midway up GKN's range of sizes and capacities.

Thanks again Brian, you sure know your driveline:) That's what I learned about this group early... I assumed it would be full of "EV" folks more than car historians and enthusiasts, but I have been proven wrong many times. There's a great diversity of skills here across all aspects of autos, old and new.
There certainly is diversity, and I agree that's a good thing! :D
 

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Discussion Starter · #56 ·
Re: 1974 BMW CSE

Turn the Brakes Around

Before we dive into our solution for the brake setup, Brett had a terrific idea to widen the area around the accelerator. The old transmission was so large that the tunnel took up a lot of space. When seated at the steering wheel, your right foot was essentially under the wheel rather than to the right. Since we have no transmission we thought we would widen the floor into the tunnel some.


My daughter Maggie had been asking to help with the project so this was her perfect opportunity. There were no gloves small enough in the shop but I did have a face mask. She did a terrific job cutting away the steel!


After the floor was cut out Tyler welded in some sections and smoothed it out. Now we have a very comfortable space for both feet. I’ll go ahead and say it: No more two left feet. (You’re welcome).



Since we have no transmission, we have no need for a transmission tunnel. My idea is to install the brake booster here - backwards. We sourced a new Bosch Hydro-boost unit which will feed a new Wilwood master cylinder.


Notice in the photo you can see where we took out some of the tunnel.

Another issue we have with the BMW brake booster is that it requires vacuum. We have no engine to provide us vacuum. We could install a vacuum pump, but it makes more sense to move to a hydro-boost style booster. With hydro-boost, the power comes from the power steering pump. Since we have a 12 volt power steering pump to power our steering rack anyway, this becomes a very elegant and unified solution.

In the photo you can see the brake setup installed securely, backwards, into the tunnel.

Enter Greg

At this point we have one huge gap in the essentials of braking. Connecting the brake pedal to the brake booster. What I call a lever, Brett named Greg.


Brett started with a piece of 3/4” inch steel plate and a plasma torch. He had made a guide and could just ride the torch along for a perfect cut.


The plasma torch provides some terrific looking metal artifacts.


We heated Greg up a few hundred degrees where he gave up his strength and we could twist him into the compound shape we needed. Once the shape was achieved, we evenly heated Greg up to get his particles all in harmony for strength.


After the cutting, cleaning, twisting, heating was done Brett welded ends on it, and the pivot point. He attached a very strong receiver to the firewall and we now have a terrific braking solution which takes up less than 2 inches of the engine (battery) compartment.


After all the designing, sourcing, fabricating, and installing, the truth will be in the pudding when we connect the brake lines to the wheels and give Greg a whirl. Stay tuned for that.

Cheers,

Paul
 

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Discussion Starter · #57 ·
Re: 1974 BMW CSE

Battery Box

Unless we plan to drive our car using a very long extension cord, we have to get our battery modules off of their cart and into the car. Our plan is to get the majority of the modules in the engine bay, with a couple more in the trunk. Here’s the story…

I've discussed earlier in this thread that while we were tempted to use Chevy Volt battery modules in order to get by with far fewer, smaller modules we simply wanted to shoot for 200 miles of range. Our car is far lighter than a Tesla Model S, but far less aerodynamic. Still, in a 72kWh configuration, when Tesla gets 240 miles of range on the highway, we are expecting to see 200 miles of mixed (as I will be doing mostly mixed city driving on my day-to-day use). I may be way off, but here's hoping...

Starting with an Open Engine Bay



We now can benefit from all the work we have done to open up that engine bay: The bulky steering box and linkage that we swapped out for our compact and low steering rack; The large brake setup which was swapped out and relocated into the transmission tunnel (thanks to Greg). We have earned ourselves a very wide open area for our new battery box.

A Sheet of Aluminum and a Table Saw

To properly mount and protect the battery modules inside the engine bay we need an enclosed box. To keep the weight down as much as possible, we built our battery box out of aluminum. By using all the space possible, our box will hold 12 Tesla modules. We will need to put 2 more modules into the trunk.


Aluminum cuts smooth and easy on a tablesaw as if it were a piece of thin plywood.


Tyler is a master with the tig welder. I learned a lot about welding aluminum on this project. Very tedious.


In between the car’s frame rails we are able to squeeze in a lower section holding two battery modules.


Here is our lower section complete with the modules slid into their tracks.


The full box is starting to take shape. We are able to get 9 modules across in the main body of the box.


Here you can see the 3 tiers of the box: 2 on the bottom, 9 across the center and 1 more on top.

continued...
 

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Discussion Starter · #58 ·
...continued


Load it up with Modules

Once the box was complete we then loaded it up with our 12 modules. We used a combination of 2/0 copper wire and copper bus bars. The wiring chain begins and ends in a junction box that was built into the bottom, and accessible under the car.


Here’s an example of a custom bus bar which connects the two bottom modules in the chain. It looks rough now but will be plated and dipped in orange to look like the ones in the next photo.


This photo shows the 9 modules across looking nice with custom bus bars. Also the cable running to the top module and down to the junction box.


Each corner of the box has brackets to secure it to the car. The corners of the box are steel reinforced on the inside for this purpose and also for living the box.


A little bit of logo work and the box looks very nice in the car. She comes in around 750 lbs. That’s about what the stock drive train and accessories, so the car is comfortable with the weight.


Very tidy underneath. You can see that we used every inch of space. If you look close you can see inside the junction box. A fuse is inserted as well. Any electrical short behind the box will blow the fuse - not the modules.


Finally, we installed the 2 last modules in the upper trunk area. This leaves plenty of trunk space. There’s even room for one more module if we ever get the desire for “more”.

Close it up and Lift it in

Here’s a short video showing how the doors attach and how the box lifts to easily drop into the car- all 750 lbs of it.

https://youtu.be/5g8GYO_5qHE

This battery box was far more work than we ever anticipated. But it turned out terrific and well worth all the efforts. This brings us extremely close to driving the car around the building. Stay tuned!

Cheers,

Paul
 

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Discussion Starter · #59 ·
Re: 1974 BMW CSE

Untethered

It’s been several months since we spun the rear wheels with the Tesla motor. When we did, the batteries were stacked in our wooden crate with a very large extension cord going to the car. Since then we have installed all of the batteries and accessories into the car, so we are able to run the car self-contained.

Finish the Trunk


Last time you saw the trunk it looked something like this photo - a gaping hole in the back of the car. Before we can move forward we need to finish out the trunk so we can keep the water out and the golf clubs in.


First we install the upper trunk floor. We had grand ideas of this section being plexiglass so we could show off the Tesla motor from up above. But batteries need to be installed into this area, so we put in a steel floor.


For the lower trunk floor Tyler started with creating a cardboard template of the trunk shape.


He then traced it to a sheet of steel, then cut the shape. Just like in 2nd grade art class, but don’t tell that to Tyler.


Tyler created ribs using a hammer and chisel. Ribs add rigidity and strength to an otherwise flimsy piece of sheet metal.


Now it’s starting to look like a professional car part.


She drops beautifully into the car to create a clean floor. The sections without ribs are where our devices will be mounted.


Next up is the vertical piece that connects the upper and lower trunk floors.


The panel fits nicely and is ready to be welded in place.


But first we add square tube supports which will support the weight of the equipment, while also reinforcing the rear of the car.

continued...
 

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Discussion Starter · #60 ·
...continued


We now have a complete enclosed trunk.


Here is the trunk from under the car. The motor now feels like it has a home, rather than hanging there exposed.

Install More Equipment

Now that we have a trunk, we can install the rest of the EV devices which will sit in the lower trunk section. There will be a carpeted false floor installed on top of this equipment, similar to the panel that hides a spare tire in many cars.



Here’s what we’ve got back there:

1 - 12v “car” battery. When the ignition is turned off, our Tesla batteries are disconnected from use. We need a small 12 volt car battery to power things like dome lights and other accessories. When the Ignition is turned on, the Tesla batteries effectively charge this car battery the way a traditional alternator would.

2 - 057 Tesla Drive Unit Controller. This 3rd party unit talks to the Tesla drive unit controlling speed, power limits, cruise control, and much more. There is more information about the 057 in a previous post.

3 - DC/DC Transformer. This box receives high voltage from our Tesla batteries and converts it to 12 volts DC. It charges our car battery while powering traditional essentials such as headlights, power steering pump and more.

4 - HV Junction Box. Just like it says- it is a junction receiving the high voltage from the Tesla batteries, the AC voltage when the car is plugged in to charge, and sends that power to and from the charger, the DC/DC converter and the Tesla Motor.

5 - Tesla Charger. This unit receives power when we plug the car in to charge. The unit converts and controls the input voltage as needed to properly charge the batteries. (Another computer will be added to control this unit).

6 - 057 Precharge Unit. This unit automates the precharge of the Tesla drive unit’s DC/AC power inverter. This is a temporary unit, whose function will be rolled into our eventual Battery Management Computer (BMS).

7 - HV Contactors. These devices switch on and off the high voltage power to the Tesla drive unit as we turn the ignition on or off. These units will be covered for safety once our charge port is installed into the old fuel fill door above.

The orange high voltage lines are complete, but the low voltage wiring is temporary. Much will be done with fuse block, relays, multi-connectors and such for a clean final result.


Here's a shot of our graceful cockpit with our custom control panel. It’s a long way off from performing any date night duties, but it’s beautiful to me.

And here's a little video of us spinning the wheels untethered:

https://youtu.be/1H0OAxUakh4

Now for the last bit of work on the brakes then we can drive this thing around the building!

Cheers!

Paul
 
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