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Discussion Starter #1 (Edited)
Hi All,

I've decided to start a build thread and will definitely need some help. I've made a few kit cars over the years but now I've decided to make my own design so will see how it goes.

Here's the plan.
1. Create a custom frame using corvette C7 suspension
2. Power will be provided by Tesla (ECU company choice as they want to make a controller)
3. Other EV parts will come from a 2012 Volt. Why because I got it for a great price (Free). I know the charger and batteries will need to be upgraded but it's a start
4. Body will be my own design.

Here is a picture of the frame along with the sister car (that's gas) and the Volt parts

 

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3. Other EV parts will come from a 2012 Volt. Why because I got it for a great price (Free). I know the charger and batteries will need to be upgraded but it's a start.
Is this car going to be very small, or short range... or will it have two Volt packs or an entirely different battery after upgrading? The Volt battery is great for high power output for its size, but it doesn't have much capacity for an EV.

Where is the battery going? One option which no one seems to choose is to keep the Volt pack intact, in the original tee form, running across behind the seats and forward between the seats. It would be forward of where it is in a Volt, relative to the driver, but in the Volt is doesn't extend all the way forward to under the dash so there should be room.
 

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Discussion Starter #3
The car will be short range. It will be long (wheelbase is 107) low (4 Inch clearance) and wide.

The batteries will use the same configuration as the VOLT but I can add to the "T" section in both width and depth (I could also double them up but I don't want the weight up that high).

I plan on mounting the Tesla motor tomorrow after I get the rear suspension back on (just had the sub frame powder coated) so I can make sure the axle geometry is correct).


 

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Discussion Starter #5
Well I made some good progress. Tesla motor is mounted. I've also got 16 kWh mounted. Found a home for 14 more. The last 2 are given me a bit of a challenge but I will get it worked out.

 

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I've also got 16 kWh mounted. Found a home for 14 more. The last 2 are given me a bit of a challenge but I will get it worked out.
I like this battery configuration - it's nice and low. Lots of people talk about putting modules in the centre tunnel, but it's not often actually done, because most stock tunnels are not large enough for production modules; the Volt modules are designed to go in a tunnel, and the custom vehicle structure can accommodate them.

Is there room for one more block between the two in the rear, or is that already the plan in that 14 kWh? It can be mounted inverted if necessary.
 

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Discussion Starter #7
In the picture the 2 packs behind the motor are 5 kWh each. The pack left over is 6 kWh and is made of three 2 kWh cells. So I might take the 1 kWh cell from the front and replace one of the 2 kWh cells. So each pack would be 15 kWh instead of the standard Vol pack of 16 kWh. That would fix the lay out but remove 2 kWh from the system.
 

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In the picture the 2 packs behind the motor are 5 kWh each. The pack left over is 6 kWh and is made of three 2 kWh cells. So I might take the 1 kWh cell from the front and replace one of the 2 kWh cells. So each pack would be 15 kWh instead of the standard Vol pack of 16 kWh. That would fix the lay out but remove 2 kWh from the system.
Just replace "cell" with "module" in that, and it makes more sense.

I don't quite get it, though...
I've also got 16 kWh mounted. Found a home for 14 more. The last 2 are given me a bit of a challenge...
but there are three modules totalling 6 kWh with no home (not just 2 modules or 2kWh) in the photo.

Of the modules in place (mounted or not) on the frame, there is a total of 26 kWh, and swapping a 1 kWh with a 2 kWh would still be only 28 kWh, and each string would need to be 14 kWh. Is there a place for one 2 kWh module which is not shown on the frame?

Perhaps I'm misunderstanding what is mounted and what is allocated a space.
 

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Discussion Starter #9
Sorry about the confusion. My first electric build and still trying to get the terms correct.

There is 6 kWh module that is in the upper left part of the picture that's not inside the frame rails (from the picture it actually looks like a 4 kWh)

Here are some better pictures.

Front 5 kWh (this is where I would take the 1 kWh from to balance the packs)


This is the center 11 kWh (The front and middle where taken out of the same Volt pack). For my build front and middle will make up one pack and right now that would be 16 kWh but after I take out the 1 kWh this pack will be 15 kWh


Both of those are mounted. I harvested the mounting plates from the Volt.

Now onto the rear section. These are not mounted yet but that's easy enough.
Each of these are 5 kWh and I can place another 5 kWh in the middle so the pack would also be at 15 kWh


So I just need to break up the front 5 kWh and make it a 4 kWh and than break up this 6 kWh and make this a 5 kWh.


That would give me 30 kWh. Not great but the weight would be very low and between the tires.

Hopefully this all makes sense.
 

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Discussion Starter #10
Sorry about the confusion. This is my first electric build and I'm still trying to keep the terms straight.

In the picture in the upper left corner there is 6 kWh not inside the frame. Anyway I took some more pictures to explain my thoughts.

Right now I've got 5 kWh mounted up front ( this is where I would take the 1 kWh from)



Down the center I've got 11 kWh


Those two would make up one pack. Right now that's 16 but after I take the 1 kWh from up front it's going to be 15 kWh

In the back I've got 10 kWh with room for 15 kWh.


So my plan is to break up this 6 kWh and make it into a 5 kWh.


Each pack would be 15 kWh for a total of 30 kWh. Range will be a bit limited but the weight is very low and right between the tires.
 

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Thanks for the explanation, and the photos. :)
In the back I've got 10 kWh with room for 15 kWh.
...
So my plan is to break up this 6 kWh and make it into a 5 kWh.
There's the key - one more block of three modules will fit between the two already shown in the rear.

It looks like the whole 6 kWh block would fit in the front (where the 5 kWh block is currently sitting; it looks made for a 6 kWh block), leaving the 5 kWh block to go to the rear, and fitting in all 32 kWh. Of course, it might not quite fit, and if it does the modules do need to be wired into two 48S sets (not one 42S set and one 54S set), so that would complicate the wiring. You could turn the tunnel set around to put the small module at the back, connect all but that small module and the front block together as one 96S 16 kWh string, and connect the three blocks in the back plus that one small module from the tunnel as the other 96S 16 kWh string... but I don't know if you can make that work in BMS connections.

If my character drawings make any sense (using "12" for a 12S 2 kWh module and "6" for a 6S 1 kWh module, and "-","|","/", and "\" for connections in a string)...
This is what you are planning:
Code:
12-12-6                  
|
12-12-6 6-12-12-12-12-12-12
      |                  |
12-12-6                  12
This is an alternative to fit in all of the modules:
Code:
12-12-6                  12
|                        |
12-12-6-6 12-12-12-12-12 12
        |              | |
12-12-6-/              \-12
It's interesting that the entire tunnel and front hold the same as the mid-rear location (where the engine is in this car's evil twin ;)).

This is the tidiest and best-distributed configuration of a battery I've seen, other than of course the underfloor approach... and this allows the seats to be significantly lower, which is valuable for this style of car.
 

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Discussion Starter #12
I can see from the pictures why you (or anyone) would think that I could have a 6 kWh up front. But there is one item which is not in the picture and its the steering column. If you look in the picture you will notice that the 5 kWh is pushed off to one side. That was to make room for the steering column, so putting the 6 kWh up front is not going to work (but it would have been a nice option)

So I think the layout will be like this

Code:
F                              12-12-6    B
R       12                     |          A
O        |  12-12-12-12-12-6   12-12-6    C
N       12-/                         |    K
T                              12-12-6
 

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If you look in the picture you will notice that the 5 kWh is pushed off to one side. That was to make room for the steering column, so putting the 6 kWh up front is not going to work (but it would have been a nice option)...
Yep, I missed the front-steer rack location, visible in an early photo. Without the steering column in place, it wasn't obvious.

The omitted 6S (1 kWh) modules are only 6% of the pack energy and voltage, so it shouldn't be a big deal. Those Tesla large drive units ran on only 84S (versus your planned 90S) batteries with the 14-module variants of the Model S.
 

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Discussion Starter #15
I've finally gotten the basic rolling chassis done. I was able to place a total of 30 kWh in the chassis in two 15 kWh packs. 15 kWh in the rear (pack 1) 11 kWh down the center and 4 kWh up front (pack 2). I going to sand the chassis and put a cheap coat of paint on it to stop the rust. When completed I going to get it powder coated. Now I've got to start working on the rest of the chassis which will be 1 5/8 tubing.

 

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Wow, I'm about 5hrs away from you but I'd love to come up and help out with this build. Happy to lend a hand in exchange for gleaning knowledge!
 

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Discussion Starter #18
Slowly but surely. It's getting done.


mocking up the charger and dc-dc


Batteries are mounted



What do you think?
 

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It's good to see everything coming together. :)

These photos show the car from new angles, and now with the wheels. The drive unit is turned to be ahead of the axle line, apparently by turning it over (keeping the rotation direction but making the bottom into the top)... right? It also looks like the motor is very high - is the drive unit tilted up at the front?
 

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Discussion Starter #20
Correct the motor has been flipped from the OEM position. I've got to redo the lubrication pump because of this but that is not a big deal.

It's real not to high. I think its just the angle. Top of the motor is 25 inches off the group.


 
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