Hacker News Reader

Comment by leesec | Hacker News Reader

These range discussions are always a bit ridiculous to me, as it's an average/guess. It's just energy so many things play a factor. How fast was the driver going? How much wind was there? How often did they use AC and stereo? Was it hilly?

People have proven time and time again if you drive a Tesla quite slow on flat ground it exceeds the driving range, and if you drive it quite fast it's below it. Congratulations.

View on HN

Whats annoying is Tesla internally knows the real range. On a trip, it picks a charging stop 180 miles away and says I will be at 5% charge when I arrive. But the mileage still says "310". If they actually adjusted the mileage display to be the real number, it would be SO much more helpful.

That is because the "range" and the "energy use for this route" are two different things. Really you -always- want the latter but people seem to think that it can be simplified to the former, it just can't.

Spherical cows in a vacuum and all of that.

Telsa puts a bunch of work into estimating energy use for a given route using elevation data etc, it's why they have their own route planner (that you can also tweak the behavior of).

From memory the only thing that goes into the "range" calc is current temperature, it otherwise just has to assume averages for everything else without knowing the route a priori.

Ok but it knows the route you are on and the mileage.

Yes, and you can view that in both the nav (on screen all the time) and the energy screen.

This would be easier to believe if their display numbers weren't always larger than the real numbers

In city driving I routinely get better range than the top number.

I drove 3000 miles in my first Time ever in a Tesla in a week and found the numbers to be incredibly accurate.

Of course they are different things. But the choice to define "range" as the highest possible number is misleading: people ask the range so that they can know how many stops are required at a highway speed trip.

Using surface street numbers for that is....unhelpful, at best. It certainly doesn't help the Windows computer hoi polloi feel as if they have gotten what they paid for.

I think they should just delete that number and just show energy and energy remaining at destination. It will annoy some luddites but it's the only reasonable way to display the actually important information, i.e will I make it and how much juice will I have when I get there.

Yup. There's a preference to show percentage rather than theoretical range. The latter is much more useful IMO, but percentage should probably be the default because theoretical range is misleading until you understand it.

> Using surface street numbers for that is....unhelpful, at best.

Strong disagree here. When doing a trip we always use the nav computer so we always have the real number. (If only so the kids can look at the computer to see the number rather than asking "how much longer" continuously).

OTOH, in town we generally don't, so the top number being accurate for in town driving is very helpful.

There’s really 3 distinct numbers that are all useful today.

“Charge” = total energy which is useful for charging but not specific route planning.

“Range” = charge * temperature which is a useful benchmark for known trips and drivers. The specific number isn’t as important vs knowing you can do regular trips between known locations in X units. ie you can commute 4 more days without charging.

“Remaining charge at destination” = most accurate route planning but requires a specific route and external temperature.

Why would it be more helpful? You already explained that the nav computer is displaying the real number. It's not more helpful to have the real number in two places rather than one. It's more helpful to have two different numbers because there really are two different numbers. The nav computer is displaying the real number for that specific route. If your plans change and you take a detour, the computer can't give you an exact number for that since it doesn't know that route and it could be vastly different. For example, if you add an extra 50 miles city driving to explore a city on your trip you will get much different milage than the highway driving your trip computer is showing you.

If it bothers you so much, go into your app and change the settings to show percentage on the top rather than range. Myself I find it much easier to mentally convert theoretical range than battery percentage (heuristics like subtract 20% for cold, etc).

Think of it like 310 is your general mileage and the estimated is the real estimate for your specific trip.

Except that there is no trip where 310 would be the real estimate for that trip. So how is it in any way useful? Tesla just takes the real range, multiplies by some made up factor and pretends that's your range.

Except it would be if you just drove it around a city. So which number should they use

This was reported on a few months ago.

This was a quote from an unnamed employee in the article “...when the battery fell below 50% of its maximum charge, the algorithm would show drivers more realistic projections for their remaining driving range...”

https://www.reuters.com/investigates/special-report/tesla-ba...

> How fast was the driver going? How much wind was there? How often did they use AC and stereo? Was it hilly?

Most of which the driver did report, in the linked post at https://www.cybertruckownersclub.com/forum/threads/10-000-mi...

> if you drive a Tesla quite slow on flat ground

I don't imagine many people looking for 320 miles between charges are planning to do it anywhere except a highway?

Unless this is a specialist product for wilderness loggers who take regular 12 hour journeys down unpaved tracks?

FWIW the top reason I'd buy a truck is so I could take it camping, but here in Colorado though it's exactly as you say. Trucks are giant, gas-guzzling status symbols that people use to get to and from work. Most aren't used to haul anything (not even an additional passenger), but that set of testicles dangling from the chrome hitch sure looks cool.

But TESLAs have so many sensors that they know all this information... Yet still choose to be misleading (and charge you a ridiculous price if you use superchargers)

IIRC superchargers are the cheapest fast chargers..?

Not sure but either way it cost about the same as gas which makes no sense... Just a money grab

You’re ignorant of energy markets and the cost of fast charging but make confident statements. Fix one or both of those

Please. We have been estimating mpg just fine for a long time and people have come to expect accurate range estimations.

this.

Electric has far higher variance, due to negative car per mile to go downhill.

More efficient vehicles have higher variance, period.

We once had a truck that would get the same mileage empty vs towing a few thousand pounds. Suffice it to say, that mileage was dreadful.

That's clearly not the problem here. Most EV makers can estimate range just fine, it's almost only Tesla that lies so much about it.

That’s because fuel has far more energy density than batteries. Yet ICE cars still underestimate mileage.

On YouTube some guys did the experiment: driving and measuring mileage after fuel gauge dropped to empty and computer started to complain about fuel. They got about 40 miles.

This is because most vehicles have a “reserve” of 1.5 gallons. So even when the gauge hits E you still have about 1.5 gallons at current MPG to make it gas station. This is get drivers to refuel sooner and not run the fuel pump dry which can cause major damage and be expensive to repair.

Yes. Many things lie to us because we can't handle the truth. Maybe they are right? I would hope for a different world.

Isn't that by design? Some law requiring that computer needs to warn you about low fuel level while you still have enough of it to get to the nearest gas station?

Reply on news.ycombinator.com