Is the Mach-E really 7 years behind Tesla?

[GoGoGadgetMachE]

I can get a 20% improvement in range by drafting a semi about 6 car lengths back.

This is certainly anecdata but I had one (exactly one) trip in one of my earlier "mild" hybrids where I was able to do that sort of drafting behind a truck pretty much all the way from home to the Chicagoland area on I-80. The in-car MPG read over 60 MPG for the trip (I reset one of the trip odometers at the start of the trip; that car didn't have a "automatically give a number for each trip" feature).

that was pretty insane.

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[GoGoGadgetMachE]

I was too close.

The "correct" answer here is that the official answer nowadays is n seconds, where you are counting seconds between the back of the vehicle passing a fixed object and the front of your vehicle passing that same object. This is what is being taught in driving classes now because it's easy to judge and takes into account speed without having to think about the sizes of vehicles, etc.

n used to be 6 (that's actually was I was taught in high school drivers education and what I was taught in an adult driving class about a decade ago), but I just did some quick research and it seems that it's now down to 3 (e.g. Rule of Seconds: A Safe Following Distance on the Highway (marksandharrison.com) )... I don't know why it dropped; I'm guessing better safety systems like everyone having ABS, etc.

Sometimes the rule is modified to take into account driving conditions, but I don't think that's as common as just a single number.

 

[Nak]

For almost everybody here this is a great video explaining the new battery technology. Long story short? The new battery technology will allow a 130 kwh battery in the same space as a 74 Kwh battery! But wait, there's more!

Sandy Munro Battery Day.

 

[macchiaz-o]

Yeah I didn't get much of his point either, beyond the sales pitch at the end. Battery sizes, form factors, and installation orientation already varies quite a bit among the many EVs built to date. I think Tesla's bigger claims were around changes that might lead to tab-less cells, less expensive chemical compositions, and Tesla attempting to move further upstream into the chemical mining and processing arenas.

Most full electric vehicle batteries are arranged by stacking cells into modules, and then modules into a large pack, with coolant running through the pack and underneath modules. The pack and modules are generally serviceable. This will be the case for the Mach-E -- local technicians can service the pack and test and replace modules, but will not go deeper than that to handle the individual pouch cells.

While cylindrical cells used to be the more common option, nowadays most EVs are using prismatic or pouch cells. It's the same stuff inside each cell (more or less), but built into a different form factor. Here's a pouch from a Kia Soul EV. Others look just like it but with varying width, height, and thickness.

Same with prismatic cells (always rectangular, but different height/width/depth):

Weber State's automotive school has a lot of online videos where they disassemble and reassemble EV batteries. You can see the same sort of high level components on each one, but with vast differences from one architecture to another at the lower levels. Here's one of their videos on the Chevy Bolt (pouch cells, though this video just shows the pack and modules):

 

[Nak]

Correct me if I'm wrong, but I'm pretty sure GM's announcement was about pouch style batteries. The reference to the Jag battery pack was about a portion of the bottom plate I think. He kind of skipped by that so I'm not sure exactly; I'd have to watch that part again.

This video wasn't about the manufacture of the cells or their cost or chemistry. It was more about how the new cell design will allow a whole new battery pack architecture. Up until now, all EV battery packs carry the batteries as cargo. The pack has structure, but the battery cell itself is cargo. With the new design, the cell itself becomes part of the structure. That's a big deal. That and the cell design allows a number of really desirable things. The structure of the car can be far stiffer, the battery cells can be cooled radially, etc. The end result is that you can build a much higher capacity battery pack in the same space as prior battery packs. As a bonus, the car will be WAY stiffer, so stiff that a convertible will actually be stiffer than old design hard tops. I would guess--but this is only a guess--that you could possibly reduce vehicle weight because you'd need less structure in the rest of the car. You'd still need impact and rollover protection so who knows.

I'm sure Tesla has patented this design, but given Elon's statement that they will sell the cell to competitors I'd expect to see much higher range for the Mach-e in a few years.

 

[macchiaz-o]

This video wasn't about the manufacture of the cells or their cost or chemistry. It was more about how the new cell design will allow a whole new battery pack architecture. Up until now, all EV battery packs carry the batteries as cargo. The pack has structure, but the battery cell itself is cargo. With the new design, the cell itself becomes part of the structure. That's a big deal. That and the cell design allows a number of really desirable things. The structure of the car can be far stiffer, the battery cells can be cooled radially, etc. The end result is that you can build a much higher capacity battery pack in the same space as prior battery packs. As a bonus, the car will be WAY stiffer, so stiff that a convertible will actually be stiffer than old design hard tops. I would guess--but this is only a guess--that you could possibly reduce vehicle weight because you'd need less structure in the rest of the car. You'd still need impact and rollover protection so who knows.

Would the cells would still be packaged into reasonably sized modules? (And if yes, how are the modules held into the vehicle frame?) The module connects the cells into the desired voltage arrangement, and allows for faulty modules to be replaced instead of replacing the whole pack. It'll be interesting to see how Tesla might "wire" everything up, and allow for battery swelling and servicing, if the cells themselves become part of the structure.

 

[Nak]

Not at all. You're missing a HUGE point. The cells themselves, each one of the hundreds of cells in the pack, will become part of the structure of the vehicle as opposed to cargo.

I went back and looked at that. He is referring to the fact that the Jag battery pack is cooled from the bottom. Desirable, but just one piece of the puzzle. Just a quick glance at the Jag battery pack confirms that the cells are not structural.

Sandy covered just that. "But they're not." Not really so easy, the cell has to be designed in a way to allow radial cooling. I get that you're not impressed that the cell will be part of the structure. You should be. That's a huge deal. If Sandy Munro is impressed by it, you might want to consider that maybe you're missing a lot if you're not impressed as well. If you understand the ramifications, you're impressed by it. Yes, it seems so simple. Lots of brilliant innovations seem simple in retrospect. Getting there is not so simple. Been there, done that.

It's not just the chemistry. It's that for sure. It's also the manufacturing and the structure. Anyone can build a one off great battery. To be useful you have to figure out how to manufacture in large quantities at an economical cost. Once you can do that you have to figure out how it will work in the structure of a car.

The chemistry won't get us EVs with a 50%-60% improvement in range. Neither will the innovative manufacturing techniques. Not even just the structure. It takes all three.

 

[Jolteon]

No, on both counts Tesla's approach is different.

GM is using "long format" pouch cells - imagine a ziploc bag full of goopy battery, but instead of 100 sandwich bags, 50 quart bags.

Tesla uses cylindrical cells, which is a fundamentally different approach to a battery. That "ziploc bag" is rolled up and welded into a cylinder can. This means that there are far more cells in a Model Y's battery than a Mach-E's - thousands more.

The Mach-E Extended Range has 376 standard format pouch cells, a Model Y has 4,416 2170 (21mm x 70mm) cylindrical cells, as an example.

Nobody has done the structural battery Tesla is proposing, because with a standard pouch cell, it can't be done.

A tray of pouch cells is not very structural - imagine all those ziploc bags of jelly glued to each other at the top and bottom. Whereas Tesla's cylinders - a grid of metal cans aligned vertically, now you've got a very rigid structure.

Tesla is proposing the car be built off the battery pack itself - that the actual floor of the car be the battery - the seats mounted to the battery, the carpet you rest your feet on being right on top of the battery, not a floor. That's not ever been done before. All EVs today including Teslas are a normal car where a battery is bolted underneath the floor. Tesla wants the battery to be the floor.

 

[Nak]

By that logic Ford is making a horrible mistake with the Mach-e. Look how many years we went without enthusiast EVs from so many auto manufacturers. There's probably a good reason.



I think the Tesla batteries are a bigger development as far as personal EVs are concerned. As far as your guarantee, you might want to research honeycomb structures before you put any money behind it. Plain and simple, you're wrong. It doesn't take much of an engineer to see the potential structural benefits.

Regardless, you have your opinion. Neither your thoughts nor my opinion are going to change what shakes out of all this. You pretty obviously dislike Tesla and it clouds your thoughts. That's cool, most folks are like that. I was thrilled that the financial community was equally slow on the uptake as it allowed me to buy TSLA stock at a bargain.

 

[dbsb3233]

Tesla is proposing the car be built off the battery pack itself - that the actual floor of the car be the battery - the seats mounted to the battery. That's not ever been done before. All EVs today including Teslas are a normal car where a battery is bolted underneath the floor. Tesla wants the battery to be the floor.

How do you replace the battery? If it *is* the frame, can you even replace it without basically taking the whole car apart?

I saw a similar thing about Tesla trying to make the entire body out of a single stamped aluminum piece. Cuts cost to build, but without separate (replaceable) body panels, a crash effectively totals the car.

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