New Roadster Goodies for 2014

[bonnie]

It was raised at the time...

Why would it be more of a problem now, then? I really don't mean to be argumentative, but if it was raised before & nothing came of it, why would that change now? It just seems like IF this were now pursued more vigorously, it would look like it was only because now UK owners realized it was worth more. (Maybe, who knows.) But if that's the case, it really should be now, not after an announcement is made.

 

[ckessel]

at the time I ordered they were going around saying the range was 300, not 265

To be fair, the 300 statement was true by the EPA test used at the time. Which is presumably why the EPA test changed, because the old one was horribly out of sync with real world usage.

 

[JRP3]

In theory newer chemistry cells like the Model S uses will have a higher C rate so they could discharge faster with a change in firmware.

Even at the same C rate the larger pack can put out more power. 56kWh pack at 1C is 56kW, 85kWh pack at 1C is 85kW.

 

[Dean412]

Elon upgrading Roadsters to 400 mile range !!

An article in the Auto Express, Elon Musk states, Tesla is planning an upgrage for owners that will increase the mileage range to 400 miles.
Elon stated that the Roadster had an old generation battery pack. Elon says we'll upgrade it to a new generation battery pack and it should have a range of 400 miles.
Being a new generation battery pack should allow Roadster owners to charge at Supercharger stations.

 

[ecarfan]

There are already multiple threads about this that were started a few days ago. I'm sure the mods will either merge or delete this one.

Note: upgrading the Roadster battery almost certainly will not mean that Roadsters will be able to use the Superchargers. That would require significant, and expensive, alterations to other parts of the Roadster's electronic systems.

 

[Ampster]

Someone on another thread mentioned that Supercharger capability is probably not going to happen without a changed interface including a direct DC switch. It is more complicated than a new battery.

 

[smorgasbord]

Those who have done the math estimate that it will be about 80 to 85 kWh to get about 400 mi. We don't know of course.

Back in 2008, the EPA said 56kWh = 245 miles. Today they'd say even less miles. But, even going with 245, unless I'm completely math challenged, I think the equation is:

56*400/245 = 91.5kWh

Assuming today's EPA would reduce the 245 to 200 (about 85%, which is inline with the previous 300 mile claims for Model S being 265 EPA), then the equation is:

56*400/200 = 112kWh

I don't see how anything less than 90kWh is possible. I'd bet on at least 100kWh, but I'm not a betting man.

 

[dpeilow]

If they use Panasonic's 14Wh cells that are not even out yet, multiplied by 6831 gives 95 kWh. Tesla may have found a way to stuff more cells in the pack but I doubt it will happen.

 

[WarpedOne]

Less weight == more range (for same kWh)

 

[Alan]

Less weight == more range (for same kWh)

"Add lightness" as Colin Chapman famously said. The Model S is a car for taking long trips (comfort, range, superchargers) whilst the Roadster is more of a raw sports car. If newer technology cells can allow higher discharge rates as well as higher capacity then I would much prefer a pack with similar range but say 150kg lighter. Assuming the weight could be taken off the top of the pack then this would improve handling, acceleration and braking all of which are key for a sportscar. These are improvements I would enjoy 100% of the time, the extra range would have been useful on perhaps 2 or 3 trips in the last 3 years.

I can however see that this a) might not be possible if less cells = less peak power & b) its probably more development work to have a different number of cells. 400 miles makes more headlines but improving the Roadster as a sports car is what I would personally prefer.

 

[Doug_G]

Less weight == more range (for same kWh)

For highway driving, only slightly. Wind resistance is the big factor, and that won't change.

 

[dpeilow]

We've already been around the less weight thing this week up thread.

And as Doug says, it's second order at highway speeds.

 

[WarpedOne]

.. but is still there. In "average case" i.e. average speed highway 'tax' takes the second row.
Aero drag increases with square of speed, "weight" drag increases linerarly.

Aerodynamics is overrated.

 

[WarpedOne]

Roadster: Power vs. Speed

At 35 mph aero-drag is only about half as big as DT-drag i.e. tires and drivetrain (TDT) eat about 2/3 of all used energy.
At 50 mph aero-drag is about the same as DT-drag i.e. TDT eat about 1/2 of all used energy.
At 90 mph aerodrag is about twice as big as DT-drag i.e. TDT eat about 1/3 of all used energy.

Tire drag == weight drag.

35 mph was my best average speed when not going on the highway. In this case 10% lower weight results in 7% higher efficiency and range.
On the highway I managed to up the average somewhere close to 50 mph, where 10% lower weight results in 5% higher efficiency and range.

5% is difference between 380 and 400.

 

[ItsNotAboutTheMoney]

.. but is still there. In "average case" i.e. average speed highway 'tax' takes the second row.
Aero drag increases with square of speed, "weight" drag increases linearly.

Aerodynamics is overrated.

It's certainly not overrated for electric cars. When range matters in a BEV you're more likely to be traveling at higher speeds. Unless you want your range to be absolutely killed by headwinds you have to have good aerodynamics.

Also, electric cars' ability to recover energy through regenerative braking reduces the overall effect of hills.

Not to say that weight reduction wouldn't be a good thing, but it's really not a priority in a long-range BEV.

 

[Odenator]

Range is king in regards to BEV's. Would anyone accept a 5 gallon gas tank in a Ferrari or Porsche to get better handling?

 

[jeremyz]

WarpedOne, the power to overcome drag is cubic, not quadratic.
Drag (physics) - Wikipedia, the free encyclopedia
Note that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power.

I personally, don't care about having more range. I would definitely prefer to have better acceleration in the 0-80mph range and better handling. I would think that a larger battery would dissipate less heat at a given power since it would be at a lower C rate. Additionally, I think that internal resistance of batteries has been going down over time. When you factor those two things together, the bigger pack might require less cooling. So that might help with the battery overheating, but it won't help with the PEM or motor overheating.

 

[MartinAustin]

At first I was puzzled why Tesla wanted to retrofit their already-sold cars with better batteries... beyond simply being nice to initial customers who in part, were critical to get the company going. (The downside being, there are only 2,600 Roadsters and it would be an expensive upgrade, since you can't use the normal factory lines etc. and profits would not come via the advantages of mass-production.)

However, it is clear now that the new battery has a new, denser chemical formula/composition, allowing more kWh in the same space. (or making the battery smaller/lower with the benefits mentioned above)

So now it is obvious why they are doing it... they want to get test data on the new denser battery composition before rolling it out to the other mass-produced platforms. With only 2,600 cars to update, and not all owners lining up in one clump, Tesla can take their time rolling out the new batteries, and place orders for component materials in small "custom" quantities, to ensure highest quality of battery construction, testing, process control and so on.

One more reason why Tesla leads the industry in electric cars.

It's possible those original 2,600 Roadsters will be regular recipients of new technology revisions in years to come!!! Essentially, owners getting special thanks for their early participation, by being early recipients of the latest stuff.

I am not saying Roadster owners will be used as guinea pigs, and exposed to experimental technology that may not be completely finished. What I'm saying is, the Gen2/Gen3 production numbers are hundreds of times larger than the Roadster production run, and Tesla wants to be a brand synonymous with engineering reliability and excellence; nobody can afford to pass up the benefit of all that in-the-field performance data.

While I'm here... I'm not convinced that the new batteries will remain incompatible with Superchargers. Even if the Roadster is uncomfortable to drive for long distances, Superchargers are a great resource to be able to take advantage of, if you're near one.

 

[jeremyz]

I've had the same thought for a while. The Roadster is a good test mule because there are enough of them to be interesting and not way too many to be crazy expensive to deal with. Plus, a very big chunk of Roadster owners are technical and would be excellent test participants.

 

[Mitrovic]

Martin and Jeremy. I do not subscribe to your point of view.

The Roadster owners will not be testers. We are not good enough for that. The roadster users will not be regular recipients for new technology ( I wish we were ).
Tesla just needs to show people: Look, buy our cars, even in the future we will support you.
They needed to find a solution for the roadsters which need battery replacement. The original roadster cells are for years out of production!
What would the public say if Tesla would let the Roadsters be stranded or immobile: They would say: "I m not going to buy any Tesla as in some years the car will be useless"
Now Tesla shows them: Buy our cars now with confidence! In several years you even could make them better. Car industry 2.0!

It is just common sense ( I was saying that for months )