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I’ve read many articles that say the CyberTruck will have the 4680 cells and the CyberTruck will be sold end of this year. I think Autoweek is somewhat biased.
Articles in Teslarati and wild speculation by Musk fans? The Autoweek article states the same end-of-2021 Cybertruck expectation, and reports that Musk is saying that it won't have 4680 cells. More importantly, even if Cybertrucks with 4680's are pouring off the line this Christmas, galderdi won't see their battery components as affordable salvage in Queensland for years, if ever.

Aside from the fantasy of the tabless cell, Tesla batteries are useless for this project. Like all production EVs, Tesla batteries are built in modules which are connected in series, so to get to any fraction of the battery overall voltage the salvage user must use that same fraction of the stock modules. Tesla only builds large-battery models, so for this project's target of roughly 1/3 to 2/3 of the usual 360 VNOM pack, 1/3 to 2/3 of the modules would need to be used, meaning for a very basic 60 kWh model (the base Cybertruck will probably have twice that) it would take 20 to 40 kWh of modules. 20 kWh might fit but would have barely adequate voltage; 40 kWh has no chance of going in the GTZ chassis.

Some modules can be broken down and reconfigured: the rare examples with prismatic cells and bolted connections (BMW i3?) can be unbolted and used easily; the most common design of stacked pouches can be disassembled and restacked but ultrasonically welded tabs must be cut apart and rejoined; the cylindrical cells of a Tesla module not only have ultrasonically welded electrical connections but are glued together in a block that can't be torn apart without destroying the pack and likely the cells.

So, the idea is to look for prismatic cells, or modules which are configured for a very small pack such as a high-capacity plug-in hybrid or a very basic battery-electric EV.
 

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The torsion test must exceed the following: Torsional rigidity should be at least 4,000 Nm per degree over the wheelbase.
Here are some photos showing the torsion tests: Clubman Builders Resource - Australian Chassis Modifications
According to the document showing the torsional rigidity requirement, 4,000 Nm per degree is only for vehicles over 1,000 kg tare mass; below that, the requirement is 4 Nm/deg per kilogram of tare mass. At 550 kg, you (and the normal GTZ) should only need 2,200 Nm per degree... if this is considered a "four cylinder" vehicle, as the GTZ is. Is the assumption that an EV is a more-than-four cylinder, or did I miss something? If this is an EV issue, why would the GTZ be certified to 4,000 Nm/degree when it is only required to reach 2,200 - was the builder allowing for V8 conversions?
 

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I realize that Australia is more Land Cruiser territory than Jeep territory, but Jeeps are sold there. If you get the 4xe hybrids which are just coming out this year, you might be able to get salvaged battery packs in a couple of years, and while I haven't seen any images of the pack's internal construction, they are reportedly using Samsung SDI prismatic NMC cells. If you are willing to use the NMC cells, it should be able to reconfigure them to suit the space. The Wrangler has a 96S 17 kWh pack, so that's 96 cells at 47 Ah each... maybe a good fit if you use a controller that can handle the 360 V voltage, or parallel pairs for 180 V and 94 Ah, or even something higher than 180 V and more than 17 kWh by using more than 96 cells in pairs. The Renegade and Compass 4xe are only 11.4 kWh, so if they are 96S as well then the cells are 32 Ah and other combinations are possible; for example, 96S2P for 22.8 kWh @ 360 V, 64S3P for 22.8 kWh @ 240 V, 48S4P for 22.8 kWh @ 180 V, or combinations of fewer than 192 cells at corresponding lower voltages and energy capacities. Cell dimensions are unknown, unless these are existing Samsung SDI cells for which specs are already published; if they are existing sizes the Jeeps just become potential additional salvage sources.
 

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Brian,
Let’s just agree to disagree.
It’s the same argument that I had with people, in the 1990’s, about NmH batteries will be making NiCads obsolete and later when I said that lithium will be the next battery technology.
 

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Discussion Starter · #65 · (Edited)
According to the document showing the torsional rigidity requirement, 4,000 Nm per degree is only for vehicles over 1,000 kg tare mass; below that, the requirement is 4 Nm/deg per kilogram of tare mass. At 550 kg, you (and the normal GTZ) should only need 2,200 Nm per degree... if this is considered a "four cylinder" vehicle, as the GTZ is. Is the assumption that an EV is a more-than-four cylinder, or did I miss something? If this is an EV issue, why would the GTZ be certified to 4,000 Nm/degree when it is only required to reach 2,200 - was the builder allowing for V8 conversions?
Brian you are right. To be honest I haven't gone into it too deep because the chassis is already certified. I am just trusting the engineer. But in verbal conversations with the chassis builder they were aiming for 4,000Nm anyway just because stiffer is better. I just grabbed the first statement I saw in the guidelines to demonstrate how tough the certification is. This (plus the engineering cost) is why I turned away from the idea of constructing my own chassis. I have made two before but never needed to have it certified against such difficult criteria. The chassis is costing a significant amount but building my own would have cost just as much, would have added 10 months to the project and wouldn't have been guaranteed to pass certification.

Even though the engineering of the chassis well exceeds the required bench mark it does not give me any latitude. Any change to the structural components of the chassis throw the previous results out the window. The new results can be estimated but estimates are not sufficient for the certification. As a result any changes to the chassis would trigger all the engineering tests which won't fit in my budget.
 

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Discussion Starter · #66 ·
I have never worked with a DC-DC converter before. I have one that will be suitable (at least while I am running 172v). I will still need a small 12v battery as the rules state that compulsory systems (lights and blinkers in my case) must still operate if the traction system fails.
So my assumption is that I will need a regulator as well so the 12v battery is not over charged? Any recommendations?
 

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The DC-to-DC converter is a regulated voltage source. I assume that you just set it to a voltage similar to what a typical automotive regulator is set to, and you don't need any other regulator.
 

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Awesome, one less component to purchase. Thanks
I went even more basic that that
I charge my auxiliary battery at the same time as I charge the main battery - and its got more "life" than the main battery

I did start with a DC-DC - I used an old laptop power supply - but when it died I just went with charging the auxiliary with an old power supply
 

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Discussion Starter · #70 ·
I am thinking of towing a trailer with some solar panels, wind turbines and an alternator off each wheel so it will recharge while I am driving. What do you guys think?
Will it need a flux capacitor before it will work?
 

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I am thinking of towing a trailer with some solar panels, wind turbines and an alternator off each wheel so it will recharge while I am driving. What do you guys think?
Will it need a flux capacitor before it will work?
Definitely need a flux capacitor! - maybe two
 

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I went even more basic that that
I charge my auxiliary battery at the same time as I charge the main battery - and its got more "life" than the main battery
That works, especially for sprint competition vehicles. I assume that's what galderdi's track car has, right?

Personally, I can't see putting tens of thousands of dollars into a street-driven vehicle, and not installing a DC-to-DC to avoid having to charge the 12 V battery every time I drive it.
 

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I am thinking of towing a trailer with some solar panels, wind turbines and an alternator off each wheel so it will recharge while I am driving. What do you guys think?
Will it need a flux capacitor before it will work?
Shhh.... don't give the perpetual motion nuts ideas! :)
 

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Discussion Starter · #75 ·
That works, especially for sprint competition vehicles. I assume that's what galderdi's track car has, right?

Personally, I can't see putting tens of thousands of dollars into a street-driven vehicle, and not installing a DC-to-DC to avoid having to charge the 12 V battery every time I drive it.
Particularly when I have a suitable one sitting on the shelf. Just a shame I need to run the 12v battery at all.
 

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Running a separate 12v auxiliary battery - with or without a DC-DC - gives lots of advantages
You can completely isolate the High Voltage pack when the car is shut down and then do the start up before enabling the high voltage

If you run the 12v stuff just through a DC-DC then the high voltage needs to be switched on first
 

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Discussion Starter · #77 ·
I have the chassis and I have started work on the buck. There may be some minor adjustment required but overall I am happy so far. Next step is to do the equivalent on the back. Then I will be connecting the dots with 8mm rod to form the contours. I can't wait till it gets to that stage as that is when it will resemble the final shape and I can commence shaping metal.

20210321_165928_resized.jpg
20210321_165952_resized.jpg
20210321_170000_resized.jpg
 

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It's great to see this progress. :)

With the chassis now in hand, can you share some dimensions, following up on the packaging challenge discussed earlier (most recently around post #36)? I was wondering about the cockpit interior width (which would also presumably be the engine bay interior width where a battery pack might go), and the width of that centre console.
 

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Discussion Starter · #80 ·
It's great to see this progress. :)

With the chassis now in hand, can you share some dimensions, following up on the packaging challenge discussed earlier (most recently around post #36)? I was wondering about the cockpit interior width (which would also presumably be the engine bay interior width where a battery pack might go), and the width of that centre console.
Thanks guys, Yup, will do. It is pretty much as I remembered. But that doesn't help with the finer detail around dimensions. There is quite a lot of unused space between the chassis structure and the front panels (above the occupant's legs). But my preference would be not to split the battery resulting in the need for cables front to rear. There is also a tonne of room in the nose and tail but I will not be using that for batteries. Those voids may be useful for some small luggage for a day trip etc. But I have a lot of time before I will need to finalise those sort of decisions. I'll get back to you with dimensions.
 
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