Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

tesla.com

Post reply on HN
Print view View original

301–310 of 358 posts

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#301

Post by kube-system »

modeless wrote: post #261
btilly wrote: post #155

Earlier quoted context omitted.

What's most striking to me as someone who has heard over and over again about how air resistance is a X^2 property, is the extent to which short (and presumably slow) trips punch above their weight in terms of range consumed per mile. From what I can tell, the actual cost here is the fixed cost of booting up some systems and electronics, and the variable costs of running them over fewer miles can make the MPGe drop.…

Starting and stopping does cost energy, but regen is pretty efficient and the lesser wind resistance of slow speeds mostly makes up for it. No, davidwhodge is right, the problem with short trips has to do with the fixed costs of "warming up" the car. Just looking at the energy graph in the car while driving it's easy to see that it's much more efficient after the car has warmed up.

Yes, but electric motor regen usually does not work all the way down to zero mph. Usually it stops somewhere around 5-10mph, and the friction brakes take over. Slow rolling traffic that fluctuates between something like 10-30mph is very efficient, but stop and go traffic fluctuating between 0-20mph is pretty inefficient.

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#302

Post by mywittyname »

zpeti wrote: post #293
short_sells_poo wrote: post #287

Earlier quoted context omitted.

Because ideally consumers should be allowed to make informed decisions, which is not possible if one party - willingly or not - misrepresents the numbers. Tesla should be criticized for every number they inflate. Every time they pull some marketing crap, they should be called out on it. If it's such a benefit as you write, why do they feel the need inflate the numbers? What happened to honesty among engineers? Unders…

Is there evidence that they are misleading or cheating? The EPA numbers (I assume) are arrived at with the same methodology for all cars. It's indepedent right? (I have no idea). So how is Tesla at fault here, if their cars do well. Btw, you can get the EPA range if you drive around 55-60mph... So it is misleading?

It is not independent. The EPA defines the test methodology and the manufacture conducts the test themselves. There are some loopholes that manufactures can leverage to improve their score, like offering a model without A/C, tiny tires, or tall gearrs; having a "eco" mode; or having a shift light on the dashboard.

The EPA test methodology is actually pretty sound. It includes things like multiple wide-open throttle accelerations to highways speeds. The problems appear to be lack of independent testing and the existence of loopholes mentioned above. Companies like Honda seem to always beat EPA #s and Ford always seems to fall very short of the numbers.

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#303

Post by edraferi »

chongli wrote: post #110
davidwhodge wrote: post #92

Earlier quoted context omitted.

I make an app (called Nikola, not the truck company) for Tesla owners that has seen over 5 MM miles driven on it. I did some quick queries to validate actual range vs. EPA range for those curious. My general takeaway is to see the EPA range as a useful, albeit unrealistic, indicator. Essentially nobody gets the EPA range, either because they choose not to go the speed limit, they accelerate harder than the EPA test f…

For the hundreds of Nikola trips with an average speed of 60 mph, the actual MPGe was about 102. Once you get up to an 75 MPH average trip speed, the MPGe drops to 94. And by 80 MPH the MPGe drops to 77. (avg over all Tesla types) That makes total sense. What I think most people don’t realize is that power is force times velocity and the force you need to apply to maintain a given velocity is equal to the friction pl…

This is why some governments raise speed limits. Faster traffic -> more energy required per mile -> more gas consumed -> more gas tax revenue

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#304

Post by lazyjones »

allendoerfer wrote: post #294
lazyjones wrote: post #255

Earlier quoted context omitted.

Perhaps not everything in life is about need. I presume what you actually wanted to say is: you don't want other people in cities to own cars.

This is a thread about EVs and how a particular feature (range) that is worse than ICU cars is improving over time, which everyone wants, because we need cleaner cars for the environemnt. Nobody in here is taking the position of saying: Who cares? Just use ICU cars forever, there is no problem at all. So I am argueing a specific point about cities. Because EV cars might be better, but are still objectively bad compar…

> but are still objectively bad compared to public transport

For whom? Certainly not for the owner.

> So no, it's not about what I want, it's about the underliying point of the whole thread: What I (or really we/our children) need other people to do.

You don't even have children. So you confirmed my interpretation: it's what you want from other people, not as you initially claimed what they need.

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#305

Post by gambiting »

WalterBright wrote: post #265
londons_explore wrote: post #237

Earlier quoted context omitted.

If you really really care about miles per gallon, nearly any ICE car the most efficient way to drive is at or near idle in top gear, going about 25 mph. The difference is remarkable - a car which usually gets 50 mpg can easily get 100mpg with that approach, although obviously you can't practically drive like that on the public highway.

I thought it was 35. But the most efficient way to drive a gas car is to speed up, then turn the engine off and coast down to a slower speed, then engine on for quickly moving up to a fast speed again. Of course, the only way you'd want to drive like that is if you are alone in the desert and need to get to a gas station.

I noticed that my plug-in hybrid Volvo does pretty much exactly this - whenever you let go of the accelerator, not only the car goes into neutral, the petrol motor does actually switch off entirely. When you want to accelerate again the electric motor kicks in first and then the petrol motor follows, so in practice if it wasn't for the small indicator on the screen you wouldn't ever know that it's happening. Considering the size and weight of the vehicle I'm actually seeing some incredible MPG when driven carefully.

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#306

Post by lazyjones »

allendoerfer wrote: post #296
lazyjones wrote: post #275

Earlier quoted context omitted.

Why? For which cities? I live in the historic city center of a large European city and own a car. It's very comfortable, safe (especially during pandemics) and useful (for transporting things) and it's almost essential for me because I pick up the kids from their mother almost every weekend and that's a 40 Km drive one way, which takes about 3 times as long with public transport (and would force me to bring them back…

I am one of those young, childless egoists and would argue, that most people do not need to own a car in cities. Renting from time to time when I actually need one works great for me. There are edge-cases and people living 40km away from their children, who are too young to use public transport, might be one of them. I am not saying it should not be allowed to own a car. There will always be edge cases, but if we opt…

> but if we optimize our rules a bit, many of the great reasons to own a car might go away.

The reasons are mostly unaffected by your adjusted "rules" (read: prohibitions). It won't get any less convenient and time-saving because you make it more expensive. You can never replace my saved time with anything worthwhile. Especially when I don't believe in the "greater good", whatever it is for you today (apparently the CO2 footprint).

> Your CO2 footprint is unsustainably big, even with an EV car, and your children have to face the consequences.

No, it's not. And first and foremost I am responsible for spending as much time as possible with my children and to keep them safe. Sorry if it feels inconvenient and scary for you, but it's not a priority for me.

> it is also ironic, that young children are the ones benefitting the most from carless environments, which is kind of the reason why young families often move out the the suburbs.

Perhaps you don't know much about young families. Most leave to the suburbs because there are too many people in the cities (= high cost of living and housing). And you know what's essential in the suburbs? Yes, cars.

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#307

Post by mywittyname »

natch wrote: post #43
steelframe wrote: post #18

I've been following a multi-month discussion over in the r/electricvehicles subreddit about EPA range. There's a growing consensus that something is very wrong with it. Here are a couple of the articles that got some discussion in that sub: https://insideevs.com/news/407807/eletric-car-real-world-ran... https://www.caranddriver.com/reviews/a30874032/porsche-tayca... As someone who has owned both a Tesla Model X and o…

It’s not just about speed, although speed has a lot to do with it (with efficiency dropping with the square of the increase). It depends also on how much you use the available acceleration features. As you will know there is quite a range of acceleration available, from barely pushing the pedal and matching normal cars, to putting the pedal about 1/4 of the way down and smoking even most fast cars, to putting the ped…

The EPA testing methodology includes wide open throttle accelerations to highway speeds.

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#308

Post by rootusrootus »

10-1-100 wrote: post #153
rootusrootus wrote: post #118

Earlier quoted context omitted.

Around town, for sure, but on a road trip with the fam I just set turn on autopilot at 70 and leave it. My wife & kids are not nearly as appreciative of the performance as I am :). But, even at mild temperatures cruising at steady speed on mostly level terrain, I generally see 325 Wh/mi. If I cruise at 75, it's 350 Wh/mi. The rated range can only be achieved by hitting about 250 Wh/mi.

Assuming you have the 20 inch performance wheels (and the Pilot 4S summer tires that come with them), those could be the difference between you getting 325Wh/mi and something more in line with 250-275 at 70mph. Here's a chart with speed/efficiency measurements for most Tesla model/wheel configurations: https://teslike.com/

That is entirely possible. When I drive out of my driveway and down the road, it sounds like the tires are ripping the asphalt off the road and flinging at the underside of the car. Sticky things.

In the winter I run snow tires, but then there's the low temperature and corresponding use of the climate control that destroys range. And in the summer I've got the performance wheels and tires installed. So I'll never see optimal range. But Tesla probably shouldn't be quoting 300+ miles of range for the Performance model, either.

Given the climate where I live is pretty mild, and snow is relatively rare and short-lived, I've given some consideration to ditching the performance tires and snow tires both and replacing with 19 inch Conti DWS to run year-round. If I got away with that on my Camaro, it would probably work on my AWD Tesla, LOL.

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#309

Post by taneq »

thdrdt wrote: post #211
taneq wrote: post #101

Earlier quoted context omitted.

All cars perform better (in terms of kWh through the driveshaft per km) at lower speed, since air resistance rises quickly with speed. Tesla can't do anything to change this, although they do try to mitigate it with good aero. Electric cars can regen brake and so recover some energy in stop/go traffic, but they're still more efficient at constant low speed than stop/go at low speed. ICE vehicles only get better econo…

This is not complete true. Most combustion cars perform best around 90km/h. Below that speed air resistance is not much of an issue but gears help a lot getting the best performance out of the engine.

Yeah, that's what I meant by "their engines are more fuel efficient at highway speeds" - fuel burn is minimized under highway conditions (90km/h as you say sounds about right) since air resistance isn't crazy yet but you're in top gear and so getting the maximum distance per engine swept volume.

Re: Model S Long Range Plus: Building the First 400-Mile Electric Vehicle

#310

Post by dabeeeenster »

csunbird wrote: post #260
jacobush wrote: post #236

Earlier quoted context omitted.

For me it has always been at a range of 1000 kilometers. (600 miles.)

It is the same limit for me. The car should be able to go until I am tired driving it, which is around 6 to 8 hours driving at 120km/h, including breaks of 15-20 minutes each 3 hours. Then I can accept a 30-45 minute break to charge if I have to continue.

If you're stopping for 15-20 mins every three hours you could probably drive for 8 hours in a Tesla Long Range 3/S right now. If you stopped at superchargers.
Post reply on HN