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

261–270 of 358 posts

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

#261

Post by modeless »

btilly wrote: post #155
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…

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.

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

#262

Post by modeless »

davidwhodge wrote: post #131
zamfi wrote: post #111

Earlier quoted context omitted.

> I made some graphs if anyone's curious, but I can't post them here. I’d love to see them!

Alrighty here's the first graph. Note that this is average speed, so any trips with an average speed near the right by definition have some parts of the trip faster than the average, so the actual drop at 80 mph isn't quite as severe as it looks. https://imgur.com/a/c10NXaz the reason for the cutoff is that because it's pretty hard to have a trip with an AVERAGE speed above 80mpg. It's very rare in my large dataset.

Cool! Can you make a graph quantifying the fixed costs of startup somehow? The startup costs do seem really high, to the point where it's pretty much impossible to hit the rated efficiency unless your trip is longer than 10-20 minutes to amortize the startup costs. I'm glad someone else has noticed this.

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

#263

Post by sokoloff »

carlob wrote: post #226
tlb wrote: post #177

Earlier quoted context omitted.

That's incorrect. Power consumption is proportional to drag * speed, and drag is speed^2, so power is speed^3, and energy per mile is speed^2.

True but we're interested in power consumption per distance traveled so it goes back to O(v^2).

That’s precisely what the last clause you’re responding to says. You’re agreeing but couching it as a “but”.

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

#264

Post by sokoloff »

Reason077 wrote: post #45
pkulak wrote: post #29

Wow, they are doing brake blending now? I'd be interested to know how good their implementation is. I always assumed they refused to do it because it's so damn hard to perfect.

Tesla doesn't do any blending of the brake pedal. Pressing the brake pedal always applies the friction brakes only. However, since a software update last year, they have had a one-pedal driving mode (Stopping mode "Hold"). In this mode, the vehicle is able to come to a complete stop without using the brake pedal, using a blend of re-gen and friction brakes to do so. In practice, it means it uses re-gen down to a very…

> Pressing the brake pedal always applies the friction brakes only

Really? That seems odd, since even my Nissan Leaf increases regen with the initial application of the brake pedal.

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

#265

Post by WalterBright »

londons_explore wrote: post #237
sgc wrote: post #46

Earlier quoted context omitted.

For ICE cars, it depends on what the mfg has optimized for. I had an Infinity years ago and I remember that it was optimized for 70mph precisely as per the owner's manual. Higher or lower speeds would be less efficient.

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.

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

#266

Post by WalterBright »

slg wrote: post #77
xvector wrote: post #49

Earlier quoted context omitted.

I was pretty bummed to learn that my Model 3's "real" range was about 70% of the "rated" range depending on how the car was feeling. Tesla definitely creatively interprets range calculations.

Have you reached out to Tesla service about this? The range being that far below what is advertised is not normal unless you are operating in some cold environments, you are blasting the AC, you are a maniac when accelerating, or you leave the car in sentry mode for extended periods of time. You might have a lemon.

Make sure the tires are properly inflated and the parking brake is disengaged. Also, drive smoothly (many people drive erratically going on and off the throttle, and emphatically deny it when you, as passenger, point it out).

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

#267

Post by alex_duf »

kylecordes wrote: post #157

It's great that Tesla keeps increasing the range, but the EPA numbers are ridiculous. I would love to see the EPA range claims for electric vehicles re-standardized to measure: * at the median driving speed on free-flowing US interstate highways * during cold weather * with some hills * using a medium level typical of drivers of cars of the price range A car manufacturer particularly focused on realism could publish…

Renault does that, they publish winter and summer realistic range. They're pretty spot on.

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

#268

Post by Shivetya »

leesec wrote: post #122

Man do I love Hackernews. Everyone is pro-innovation, pro-future, pro-forward thinking until literally anything new happens, in which case everyone shows up with a "well, ackshually", to tell you why the new idea is dumb. It's amazing to me that Tesla continues to increase State Of The Art range and EV efficiency, at scale, for cars that already smoke the competition. I hope their fervor to improve the technology nev…

I am cheering on their ever increasing range for one reason.

It will force traditional manufacturers to step up. They all seem too content to deliver products whose range numbers barely make it to the mid two hundred mile range number.

This is the same complacency that would have doomed us forever to a world of sub one hundred mile range EVs when Tesla was not a factor.

They just don't want to push the numbers because the longer they drag their feet and the slower the number increases the more profit they can wring out of the market.

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

#269

Post by Klathmon »

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.

Tesla's are already very close to that right now.

I used to drive from Florida to Pennsylvania fairly often, and in my model 3 it's a rough cadence of drive for 2.5 to 3 hours, stop at a supercharger for under 30 minutes, repeat until I'm there.

And that's with the vast majority of the trip at 75mph/120km/h.

It does get worse in the winter though, I need to stop more frequently like every 2 hours, and for more like 30 minutes per stop.

Post reply on HN