Cotton Commie Conversion - Trabant

If anyone is wondering what the heck is a Trabant... Built from 1957 through 1990 in East Germany, it received virtually no modification starting with 1963 "model year".

A good (and funny) read is in the link below. Here's an excerpt:

https://upost.info/en/31373838383434383833

And an interesting fact: The new VW ID.3 electric car will be made in the same factory as the Trabants

Indeed, the frame is steel and only the body panels are made out of Duroplast. The only panels that were later made from steel were the grille and hood.
The general urban myth is that it's made out of corrugated cardboard

brian_ said:

Where are you putting the battery? My guess is half of less of it under the hood, on top of the motor, and the rest in the back seat area or the trunk.

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As I'm going to use the Volt BMS slaves, the plan is to keep the blocks together as they were in the Volt:

The rear box will go in the trunk as I am hoping to keep the back seats.

In the front, the Trabi has something which resembles a shelf next to the firewall (not my car):



I'm planning to use that conveniently designed shelf and have the battery located between the motor axis and the firewall. Depending on the space available in the front, I will decide which battery string goes where.

BogdanT said:

The only panels that were later made from steel were the grille and hood.
The general urban myth is that it's made out of corrugated cardboard

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The hood's cardboard must have sagged, so it was changed to steel, while the vertical panels didn't have this problem.

BogdanT said:

As I'm going to use the Volt BMS slaves, the plan is to keep the blocks together as they were in the Volt:

String1: 4KWh + 4KWh (BICM 2&3)
String2: 5Kwh + 3KWh (BICM 1&4)​

The rear box will go in the trunk as I am hoping to keep the back seats.

In the front, the Trabi has something which resembles a shelf next to the firewall (not my car):

I'm planning to use that conveniently designed shelf and have the battery located between the motor axis and the firewall. Depending on the space available in the front, I will decide which battery string goes where.

Click to expand...

Something like that shelf is a typical feature of car bodies from the era of the Trabant; later, the base of the windshield was further forward so that space ends up in the interior behind the firewall. I'm surprised that this area is large enough for roughly half a set of Volt modules, but if it works that's great. It's undesirably high, of course, but that's inevitable in most conversions.

Despite the nominal capacities being listed as the same, I don't think that the two strings have the same number of cells, or are the same length (which depends on both cell count and how they are broken into modules), but they are similar and it looks like you realize this anyway.

There may not be a long enough stretch in the trunk, either - most people using Volt modules end up having to split them to the next level down (at the electrical interconnections, keeping the mechanical connections between modules). I can't find it at the moment, but someone in this forum did a Sprite or Midget and put what looks like half a set of Volt modules in the trunk... broken into two rows.

brian_ said:

I'm surprised that this area is large enough for roughly half a set of Volt modules, but if it works that's great. It's undesirably high, of course, but that's inevitable in most conversions.

Click to expand...

As the ICE is still in, I've roughly measured, but it will easily fit a 4KWh block (24S) with some room to spare behind the strut mounts. After the ICE is out I can actually check if the large 5KWh block fits.

brian_ said:

Despite the nominal capacities being listed as the same, I don't think that the two strings have the same number of cells, or are the same length (which depends on both cell count and how they are broken into modules), but they are similar and it looks like you realize this anyway.

Click to expand...

Maybe I'm missing something but the strings should be identical in terms of cell count; but differ only in size. This is my diagram for the Volt battery split into 2 parallel strings. It should show the exact config by block/module.
The transformation would be from 96S-3P (in the Volt) to 2P-48S-3P in my setup.

brian_ said:

There may not be a long enough stretch in the trunk, either

Click to expand...

Boot is surprisingly large; the only challenge there is mostly finding mounting points for the battery box (that are not paper-thin, poor quality steel).

BogdanT said:

As the ICE is still in, I've roughly measured, but it will easily fit a 4KWh block (24S) with some room to spare behind the strut mounts. After the ICE is out I can actually check if the large 5KWh block fits.

Click to expand...

Sorry, I thought that you meant that you were planning to put an entire string of two blocks, or half the pack, on that shelf. For one block it certainly looks long enough.

BogdanT said:

Maybe I'm missing something but the strings should be identical in terms of cell count; but differ only in size. This is my diagram for the Volt battery split into 2 parallel strings. It should show the exact config by block/module.
The transformation would be from 96S-3P (in the Volt) to 2P-48S-3P in my setup.

Click to expand...

First, that's an excellent illustration. It's the first-generation Volt battery, which appears to be the one commonly used, presumably due to availability.

I missed that you were reconfiguring the blocks into two equal-length (in cell count) strings, although of course you said that, and it's the sensible way to use a Volt battery with a lower-voltage motor. When you mentioned "the plan is to keep the blocks together as they were in the Volt", I was thinking of the physical arrangement of the Volt pack (one set of modules down the tunnel for 54s3p and 9 kWh, a different length set of modules across under the rear seat for 42s3p and 7 kWh). What you're keeping is the combinations of modules within each block, not the way the blocks are connected to each other.

Presumably in the Volt BCIM 1 is at the front, with BCIM 2 behind it, then BCIM 3 and BCIM 4 across the back.

So it's all good, and apparently I need that second cup of coffee.

BogdanT said:

Boot is surprisingly large; the only challenge there is mostly finding mounting points for the battery box (that are not paper-thin, poor quality steel).

Click to expand...

Paper-thin, poor quality steel - that's the whole car, isn't it?
The solution is presumably some sort of subframe which can attach at many points, spreading out the load.
Of course now that I understand that you're not trying to put two blocks end-to-end across the car, there should be enough room.

brian_ said:

Of course now that I understand that you're not trying to put two blocks end-to-end across the car, there should be enough room.

Click to expand...

Goes to show that I need to be more specific with the descriptions. I'll target to update the first post with more details as they come along.

Tremelune said:

Neat!

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Can't believe I missed your conversion topic

On my side there are a couple of requirements to actually pass the inspection and have it registered as electric.
DC/DC is a must, and I will have to keep all the lights original (halogen), at least for the inspection.
I will need to have some sort of heating installed; but I'm planning to tick this box with some crappy 12V china thing for the inspection.

I'll swap the existing battery for a smaller 10Ah one, and shop for a DC-DC while I'm getting my plan sorted out. Need to figure out if I'll go for Type2 connector from the start, and if my diagram has any major flaws in it


Random pic... me, Traby and a Mini

Finally work has started.

Started by weighing the car empty of ICE stuff -> 250kg front, 250kg back. Original weight with ICE was 400(F) and 300(B), so the target is to stay below 450kg (front) and 350kg (back).

4+4 KWh are going in the back of the car, with a very tight fit between the wheel wells

In the front, the 5kw and 3kw have been reconfigured to 4+4 and fitted on a V-shape frame, with the junction box in between the V and the SolitonJR on top.

Kostov K9 is bolted on the gearbox and mounted (ditched the clutch, went for a lovejoy-type coupling).

Next up is to get the BMS loom sorted (original loom + Volt slaves) and hook up SimpBMS.

Front box somewhat in position.



Wiring up the SolitonJR




And playing around with some micro-oled displays. They are built on some blank button frames I had in the dash.

Good luck with your build, my wife is from East Germany, and I surprised her with one in the USA about a decade ago. We enjoyed the annual parade in DC with it at the Spy Museum. Unfortunately when I had a choice between taking out the Mini or the Trabant, Mini usually won. Very fun car in a weird way, but pretty hard to use on American Highways, lol!

Happy new year!
Slowly piecing stuff together, a couple of test drives already and a lot of mechanical work pending.

And ... a ton of time spent on reworking some of the code on the SimpBMS-Ampera version

http://instagr.am/p/CJvC0opJYpI/