RE: Tesla Model S: Review

[underphil]

98elise said:

Then you will understand that it has a very flat torque curve, and it doesn't need a gearbox to get over the torque/rpm limitations of an ICE?

The downside for single speed an EV is that it will get to maximum revs at a relatively low speed for a 400bhp car. If you want a car with gears that can go 160+ then an EV is possibly not for you.

Personally top speed doesn't interest me, acceleration does

Is that how this one works though?

If it has a flat torque curve, and only makes 416bhp when it gets to 130mph, that would mean that it has only 192bhp when it reaches 60mph - yet it weighs over 2 tonnes and does it in 4.2 seconds ??

[anonymous-user]

TooMany2cvs said:

skyrover said:

Here's a wild idea... how about the government stops taxing us so fking much?

Sure. So which third of the NHS would you like to give up, in order to get the budget back - at least - to it's present state of imbalance?

How about the third that gets flushed down the toilet every year due to constant changing of governance and procedures, along with the ridiculously overpriced NHS IT projects.

[anonymous-user]

TooMany2cvs said:

BUT... let's not forget that the Gov't receive somewhere around £30bn in fuel duty per year. Unless there's a non-negligible amount of shift from internal combustion to electric, how's that gap going to be filled? That fuel duty income is about 5% of the total Gov't annual expenditure - or a third of the total NHS budget.

Removing one source of tax, however large, does not stop the government from increasing a dozen others, or coming up with a myriad of new ones. [Not that this line of argument is actually related to the original story anyway]

[McWigglebum4th]

KimJongHealthy said:

Forget about those rapid charges in motorway services and other nonsense. Solution is extremely simple and already there (battery swaps). All we need are manufacturers agreeing on standardised battery modules.

Or make motorway service stations nice places to be so spending 30 minutes there is unpleasant

Actually


Thinking about it

Nope electric cars will never work

It's asking the impossible

The tech will never work

A pleasant service station


I must be bonkers

[DonkeyApple]

ging84 said:

DonkeyApple said:

Erm, it's an electric motor.

do you think i thought it was a rocket motor?

Of course not. They have linear torque as well.

[JonnyVTEC]

[underphil]

JonnyVTEC said:

the torque curve for the 911 is way off

120nm at 2000rpm - I don't think so

[ging84]

an ideal motor would have a torque curve like that which is a perfect arc
essentially having enormous torque at lower rpm and almost zero at huge rpms, and having an absolute flat power output.

Real world motors can't work like that, which is why you see the initial flat phase is where it is torque limited, so power curve goes up
what you can't really see from that other graph is what happens at higher rpms, where the motor is becoming less efficient

this one also shows the power curves

[theaxe]

Has anyone posted this link to The Oatmeal cartoon on the Tesla yet?

Edited by theaxe on Sunday 24th May 18:58

[Talksteer]

98elise said:

ging84 said:

DonkeyApple said:

Erm, it's an electric motor.

do you think i thought it was a rocket motor?

Then you will understand that it has a very flat torque curve, and it doesn't need a gearbox to get over the torque/rpm limitations of an ICE?

The downside for single speed an EV is that it will get to maximum revs at a relatively low speed for a 400bhp car. If you want a car with gears that can go 160+ then an EV is possibly not for you.

Personally top speed doesn't interest me, acceleration does

A relatively simple 2 speed transmission would allow the model so to reach around 18th.

However the additional cost and drag of the gearbox is not really worth it to give a mostly theoretical increase in top speed.

[JonnyVTEC]

Actually speed optimsation of the motor to road speed is likely to benefit efficiency by walking the power electronics etc to their sweeter efficiency spot and avoids geberating pointless heat. It's not like the motor currently is direct drive so there are no addition 'drag' gears to transmit power through if you have a multi speed gearbox. It has a gearbox already - a single gear.

[swisstoni]

kambites said:

Debaser said:

Anything you plug in can take advantage of economy 7, so you can charge your EV with cheaper electricity overnight.

Hmm, that's not how the setups I've used have worked - my parents used to use it for night storage heaters and they were on an entirely separate meter with its own consumer unit. Things like the lights and ring mains couldn't be used at the lower rates.

When I last looked into Economy 7, it was simply a different tariff that kicked in overnight. No extra kit. People would charge up their storage heaters, immersion heaters, run appliances etc during these hours. Downside was that that the daytime tariff was higher than standard, so you had to do your homework to see if it was worth it.

[98elise]

underphil said:

98elise said:

Then you will understand that it has a very flat torque curve, and it doesn't need a gearbox to get over the torque/rpm limitations of an ICE?

The downside for single speed an EV is that it will get to maximum revs at a relatively low speed for a 400bhp car. If you want a car with gears that can go 160+ then an EV is possibly not for you.

Personally top speed doesn't interest me, acceleration does

Is that how this one works though?

If it has a flat torque curve, and only makes 416bhp when it gets to 130mph, that would mean that it has only 192bhp when it reaches 60mph - yet it weighs over 2 tonnes and does it in 4.2 seconds ??

Acceleration is driven by torque at the wheels, not engine power. This is why an ICE car will accelerate better in a lower gear than a higher gear. ICE cars also produce low torque/power at low revs, which is not ideal.

An EV can produce maximum torque at zero revs, which exactly what you want. It also has enough rev range to only need one gear. You could have extra gears, to alow an EV to go faster, but its just not needed, so why add the complication cost and the extra drivetrain losses.

Edited by 98elise on Friday 30th May 09:12

[donteatpeople]

JonnyVTEC said:

Actually speed optimsation of the motor to road speed is likely to benefit efficiency by walking the power electronics etc to their sweeter efficiency spot and avoids geberating pointless heat. It's not like the motor currently is direct drive so there are no addition 'drag' gears to transmit power through if you have a multi speed gearbox. It has a gearbox already - a single gear.

There are a couple of bikes at the TT Zero that use gearboxes for exactly this reason. It means they can use more power for longer and still finish the race. I'm not sure if it's as relevant to road cars as it is to race bikes but it's an interesting variation.

[dino ferrana]

KimJongHealthy said:

Forget about those rapid charges in motorway services and other nonsense. Solution is extremely simple and already there (battery swaps). All we need are manufacturers agreeing on standardised battery modules.

There are no battery swap stations in operation in the UK, in fact I am not sure any are now operating globally because Better Place is borked.

Battery swap is not in an way extremly simple. The tech to do it is complex (alignment, handling of batteries, battery management etc.) and VERY expensive. Battery swap stations even at small capacity are looking like £1million! A quick charger is I think around £10k depending on spec, with another chunk for install, which varies depending on existing infrastructure. There are already over 220 quick chargers in the UK, that is approaching a national network (www.electrichighway.co.uk). As I understand it, Tesla are installing a network of their Superchargers in the UK at a low density because of the larger batteries their cars use. I think the first one has already gone in.

Standardised modules are not going to happen and to say "all we need" is I'm afraid rather underselling the technical and practical challenges. To have standardised modules means standard size and single chemistry and construction. Although most electric cars on the road are Lithium Ion, their chemistry and constructions are TOTALLY different. Each technique has its up an down sides and car companies will play with these to get what they feel is the best balance of cost, reliability, power output, longevity and safety. A fixed tech means they hold back any battery development and if a big change does come it means removing all batteries from the swap stations, replacing and reporgramming/upgrading existing cars. Nightmare

Standard battery packs would also impact on putting the things in the car. Current packs are either squeezed into spaces where a diesel engine and gearbox was or similar, or formed to a bespoke car in the case of Nissan, i3 and Tesla. Going standard shape, means you lose the ability to use this to your advantage. The Nissan Leaf boot is pretty big for a family hatch and the Model S front and rear boots are VAST. Standardised packs would eat into this as the shape could not be optimised for the car. With EVs coming as 4Wd, saloons, hatches, city cars etc. in the near future, one shape of battery would be a major pain.

Quick chargers are a far better solution for longer journeys, but let us remember that the majority will not use these all the time. For those who don't have off-street parking then we will have to see councils making EV only bays in on-street parking like I saw when I went to Oslo. This means if you have say 10 bays, 1 or 2 are EV depending on demand and have a charge point. A couple more could be plug equipped and be changed to EV only as more and more cars go electric.

[I WISH]

Very handsome machine ...... and its difficult to argue against those performance figures.

If it was £40k it would sell like hot cakes.

[kambites]

swisstoni said:

kambites said:

Debaser said:

Anything you plug in can take advantage of economy 7, so you can charge your EV with cheaper electricity overnight.

Hmm, that's not how the setups I've used have worked - my parents used to use it for night storage heaters and they were on an entirely separate meter with its own consumer unit. Things like the lights and ring mains couldn't be used at the lower rates.

When I last looked into Economy 7, it was simply a different tariff that kicked in overnight. No extra kit. People would charge up their storage heaters, immersion heaters, run appliances etc during these hours. Downside was that that the daytime tariff was higher than standard, so you had to do your homework to see if it was worth it.

Maybe it's changed. It's at least 15 years since my parents used it.

[Mr Gear]

It will sell like hot cakes anyway

[kambites]

I WISH said:

Very handsome machine ...... and its difficult to argue against those performance figures.

If it was £40k it would sell like hot cakes.

Most cars would sell like hot cakes if they were less than half the price of their direct competition.

They seem to be selling pretty damned well regardless.

[98elise]

I WISH said:

Very handsome machine ...... and its difficult to argue against those performance figures.

If it was £40k it would sell like hot cakes.

Their next car after the Model X is supposed be a $30-40k family car. Thats top end mondeo money. The shame is that the S is not in full production yet, and the X is still a prototype, so we're a few years from the next car.

Tesla are already turning a profit as a company with the Model S, and they are using a small fraction of their factory space to build it. They have their sights on the mass market, and they are one company that can do it.

Its a pity that Top Gear (and other journalist) chose to fake their tests of the Roadster to make it seem the technology was crap. The Model S is the turning point, its too good and too well recieved to do a hatchet job on it.