EM on Twitter: 'I think we will probably stop at 100 kWh on battery size'

[rypalmer]

I don't know nearly enough about battery chemistry and supercharging, but would having two smaller batteries (e.g 2 60kWh for a total of 120) increase the supercharging time given the whole 'don't want to fill a glass too quickly at the top' metaphor?

No.

Imagine that each "battery" it's just thousands of 18650 cells. How you package them doesn't matter, from a cell charging perspective (other details such as overall pack voltage does matter of course, since this dictates what current is required to achieve whatever kWh you hope to pump into the pack...).

 

[wdolson]

As batteries improve from here, if the packs stay the same energy, the weight and cost will continue to drop. Reduced weight mean more range. That why the Bolt gets 238 range out of a 60kWh battery.

With enough weight reduction, the Model S could get probably get 400 miles of range from 100 kWh pack, which I think is a very reasonable range to stop at.

They will probably never get that kind of range out of a 100 Kwh pack. The car will always weigh more than 4000 pounds, there is a lot of car there that isn't battery.

He may have tweeted that as an anti-Osborne effect thing. I could see Tesla sitting at 100 KWh as the largest pack for a year or two, and when the larger cells become available provide a next generation pack with fewer cells and the same capacity. That would make the pack a lot cheaper.

If they plan to continue offering the S/X, which it appears they will, they need to do something to differentiate them from the 3/Y. The X will have the falcon wing doors and panoramic windshield, but the S won't have much to differentiate itself other than the hartchback. If the S could get to 500 miles on a charge, that would be a selling point for those who want to skip stopping on a day's drive. That would destroy all arguments about range, and allow someone to pretty much drive all day on only one charging stop. But that would require something in the neighborhood of 150 KWh to achieve.

 

[wdolson]

No.

Imagine that each "battery" it's just thousands of 18650 cells. How you package them doesn't matter, from a cell charging perspective (other details such as overall pack voltage does matter of course, since this dictates what current is required to achieve whatever kWh you hope to pump into the pack...).

The pack could be divided into two parts and have a charging port on each side of the car. One port charges one half and the other port charges the other. That would allow faster supercharging if you could get the two ports on two different circuits, but that isn't guaranteed, and it would mean you'd hog two supercharging ports to charge, which would be annoying to everyone else.

Even if you did get two ports on different circuits, you probably would not get 2X the charge speed. Charging speed is at least partially a factor of the size of the pack. If the charge is spread over fewer cells, it can't go as fast. You're ultimate limit is the speed at which individual cells can charge and the current supercharger tech is close to the max limit of this cell's chemistry. You might get a 50% improvement. Maybe.

It is sort of technically possible, but logistically Tesla would be nuts to do it.

 

[malcolm]

I imagine that for the S, pushing beyond 100kWh would require a move to the 21700 format.

 

[mikeash]

Charging speed is mostly if not entirely limited by pack size and cooling capacity. Splitting the pack in two with two charge ports wouldn't help, since the charge port isn't the limiting factor.

 

[wdolson]

I imagine that for the S, pushing beyond 100kWh would require a move to the 21700 format.

It will, but they will be switching to those cells in less than a year.

 

[Owner]

That's disappointing. I want more range. I like to go to really really out of the way places where charging is a hassle, and you have to loop around. Here's my example -- the article is about the trip planner but you'll see the maps.

Remote Trip Planner Test

 

[malcolm]

It will, but they will be switching to those cells in less than a year.

Yes, absolutely. But given that BMW, Audi etc are nowhere near challenging the S, Tesla don't need to re-engineer the S's pack next year.

 

[hmmm]

He said battery size...not number of batteries per vehicle....just a thought.

 

[green1]

Yes, absolutely. But given that BMW, Audi etc are nowhere near challenging the S, Tesla don't need to re-engineer the S's pack next year.

This is exactly it. Tesla has ZERO competition right now. Why bother trying to get even further ahead?

Come back in a decade and re-visit this. The answer may change dramatically. Rest assured that Tesla won't stick to 100kWh packs when the competition has twice the range.

 

[Racerx22b]

He explained in a tweet or blog or something shortly after the release of P100D that 100kWh was all that could be achieved from this batter pack. Meaning, a new battery pack would need to be developed to go bigger.

 

[eloder]

As others mentioned it's probably a "current chemistry" issue and model issue, not that they will forever be stuck at 100 kwh. I expect Tesla to someday have 300 kwh batteries on the high-end models, but that just may be decades away.

 

[demundus]

If you're mainly an around-town driver, and/or the SpC network is good enough, why would you want to carry around the extra
weight of an ultra-high-capacity battery rather than having a smaller, lighter battery that allows your car to be more nimble and
consume less energy on average? I predict, as the SpC network continues to expand, that the obsession with battery size will
increasingly be a throwback to early EV days. This is one of the reasons I think the new 60s are so exciting -- they exist in a different
world than existed when the original 60s came out.

QFT: I wouldn't have considered a 60 when I was looking for my 85... now a 60 seems just fine.

 

[malcolm]

The headache for Mercedes and the rest is that if they market a Tesla-killer which can beat today's 315mile/2.5second/$115k S then they undermine their own business

Musk has just told an entire industry: Go Osborne yourselves

 

[ggnykk]

damn, i was hoping for at least a 120 kwh battery before i take the jump to Tesla.

 

[J0RDAN]

I think he means 100kWh with current technology / cell chemistry. Having read his bio, I don't believe he thinks technical progress will come to a halt. When it does there's usually a paradigm shift and a new technology emerges (vacuum tubes to transistors).

 

[Evbwcaer]

One thing that may put pressure on battery size in the future is when cars are grid connected.

If your car allows you to buy low and sell high to the power company, you could potentially make your car into a small revenue source.

In this way, considerations other than driving/range/charging could influence battery size.


As batteries become cheaper and have more KwHs, and as more solar/wind come online, this becomes a more plausible scenario.

 

[RogerHScott]

If your car allows you to buy low and sell high to the power company, you could potentially make your car into a small revenue source.

The possibilities boggle the mind: grid in region X trades at $S/kWh, grid in adjacent region Y trades at $T/kWh, T>S; park on the X side of the X/Y line, charge up, drive over the line to Y, sell your electrons for a profit. 'Course, only works if T - S is greater than the losses involved, etc.

 

[InternetDude]

100 kWh isn't big enough when you live in Saskatchewan. Basically 800km+ from the nearest supercharger with no plans to install any in the province (according to their map anyway). But for the US and Europe, yeah 100 kWh is more than enough for the majority.

 

[Dave EV]

Charging speed is mostly if not entirely limited by pack size and cooling capacity.

With the current cell technology used by Tesla, yes.

In general terms, charging speed is limited by the internal resistance of the cells and how safely you can push the cells beyond their maximum safe voltage.

All else being equal, cells with lower internal resistance can be charged faster. There are lithium cells that can be charged to 80% in less than 10 minutes. But the drawback is that they can't hold much energy. Tesla has opted for cells that hold a lot of energy, but have relatively high internal resistance. If Tesla opts to cap total pack capacity around 100 kWh (I agree with others that 100 kWh is not quite enough for less efficient vehicles like the X), then I expect them to focus on reducing cost, size/weight and internal resistance (probably in that order).