LR True Range -- Part II, Early Evidence

[omgwtfbyobbq]

Why do people keep talking about 78 kWh battery available? By my calculations it is closer to 70-72 kWh. In every single trip I did so far the actual kWh used divided by the rated range miles used is rock solid around 232-233 Wh/mi. If you multiply that by the optimistic 310 miles you get a total available battery of 72.23 kWh, if you multiply by my actual max range (5 full charges so far, they showed 300,300, 301, 303, 301 miles), 70.1 kWh.

78+kWh is what Tesla recorded on their EPA application. Course, this is driving at a steady 55mph for most of the test. IRL, with higher average discharge rates, the battery won't provide as much energy. There's likely still a little juice left after empty, but I wouldn't count on going very far.

 

[gregincal]

78+kWh is what Tesla recorded on their EPA application. Course, this is driving at a steady 55mph for most of the test. IRL, with higher average discharge rates, the battery won't provide as much energy. There's likely still a little juice left after empty, but I wouldn't count on going very far.

78 kWh is 78 kWh no matter how fast you drive, the battery should provide the same mount of energy no matter what the discharge rate (you’ll just use up the battery faster). The Model 3 gauge goes to 0 after using about 73kWh though (again, regardless of how fast or slow you drive).

 

[omgwtfbyobbq]

78 kWh is 78 kWh no matter how fast you drive, the battery should provide the same mount of energy no matter what the discharge rate (you’ll just use up the battery faster). The Model 3 gauge goes to 0 after using about 73kWh though (again, regardless of how fast or slow you drive).

I wish! Even Lithium battery energy varies depending on temperature and discharge rate. There isn't as much variability as there is with lead acid, but there are still differences depending on how the battery is discharged.

https://pdfs.semanticscholar.org/6756/ff155ea5477dc075a0ad79deac21bc587369.pdf

 

[gregincal]

I wish! Even Lithium battery energy varies depending on temperature and discharge rate. There isn't as much variability as there is with lead acid, but there are still differences depending on how the battery is discharged.

https://pdfs.semanticscholar.org/6756/ff155ea5477dc075a0ad79deac21bc587369.pdf

Well OK, sure. Sometimes it seems to track going to 0 after about 68 kWh under adverse conditions. But never ever anything more than 73 kWh.

 

[Zoomit]

...still waiting on someone to hit 0 mi range and keep on driving.

 

[Dr. J]

...still waiting on someone to hit 0 mi range and keep on driving.

AND report how far they went after hitting zero miles.

 

[omgwtfbyobbq]

It looks like it keeps going and some systems start to drop out. In the comments they said they went 3 miles and then sat for a bit before charging.

 

[omgwtfbyobbq]

Well OK, sure. Sometimes it seems to track going to 0 after about 68 kWh under adverse conditions. But never ever anything more than 73 kWh.

It might be possible to pull 80+kwh if someone were to drive it at a steady 40mph for 11+ hours. Not that anyone should do that, but they could.

 

[Reid]

I disagree. While some ICE cars can be driven significantly past zero miles remaining, others can’t. Some cars have a buffer to protect their fueling equipment (a good example of this is a new VW TDI that leaves one gallon of buffer in the tank because the high pressure fuel pump is cooled and lubricated by fuel - running too low will damage it).

My Escape shows empty and Zero miles remaining with 8 litres (2 gal) left in the tank. Same fuel pump issue. It will burn out if run completely dry.

I'm not sure how much more true it is of HPFP but people have been saying your fuel pump will burn up from running the fuel too low for DECADES, long before in-tank HPFPs. I've made an art of running my cars to 0 range and beyond (which I WON'T be doing with the 3). Generally the low fuel light comes on where the "Reserve" quoted in the manual is, and even 0 range is not 0 range. Accidentally ran my Golf to about -10mi range in Death Valley, and my BMW I know when it starts cutting out on right hand turns that it's down to about 1/4gal left. Yes, I once ran out of gas waiting in line at Costco. But hey, 150k miles, still on the original fuel pump

 

[Big Earl]

I'm not sure how much more true it is of HPFP but people have been saying your fuel pump will burn up from running the fuel too low for DECADES, long before in-tank HPFPs. I've made an art of running my cars to 0 range and beyond (which I WON'T be doing with the 3). Generally the low fuel light comes on where the "Reserve" quoted in the manual is, and even 0 range is not 0 range. Accidentally ran my Golf to about -10mi range in Death Valley, and my BMW I know when it starts cutting out on right hand turns that it's down to about 1/4gal left. Yes, I once ran out of gas waiting in line at Costco. But hey, 150k miles, still on the original fuel pump

High pressure fuel pumps have only been out for just over one decade. Don’t confuse a high pressure fuel pump for a modern common rail Diesel engine with a regular old in-tank fuel pump in a conventional gasser.

 

[Sparky4life]

What's an RM? What is your conclusion regarding actual Wh/mile? I'm so confused.

I was confused too. Too many acronyms! I'm with Elon.:

From time to time, Musk will send out an e-mail to the entire company to enforce a new policy or let them know about something that's bothering him. One of the more famous e-mails arrived in May 2010 with the subject line: Acronyms Seriously Suck:

There is a creeping tendency to use made up acronyms at SpaceX. Excessive use of made up acronyms is a significant impediment to communication and keeping communication good as we grow is incredibly important. Individually, a few acronyms here and there may not seem so bad, but if a thousand people are making these up, over time the result will be a huge glossary that we have to issue to new employees. No one can actually remember all these acronyms and people don't want to seem dumb in a meeting, so they just sit there in ignorance. This is particularly tough on new employees.

That needs to stop immediately or I will take drastic action - I have given enough warning over the years. Unless an acronym is approved by me, it should not enter the SpaceX glossary. If there is an existing acronym that cannot reasonably be justified, it should be eliminated, as I have requested in the past.

For example, there should be not "HTS" [horizontal test stand] or "VTS" [vertical test stand] designations for test stands. Those are particularly dumb, as they contain unnecessary words. A "stand" at our test site is obviously a test stand. VTS-3 is four syllables compared with "Tripod", which is two, so the bloody acronym version actually takes longer to say than the name!

The key test for an acronym is to ask whether it helps or hurts communication. An acronym that most engineers outside of SpaceX already know, such as GUI, is fine to use. It is also ok to make up a few acronyms/contractions every now and again, assuming I have approved them, e.g. MVac and M9 instead of Merlin 1C-Vacuum or Merlin 1C-Sea Level, but those need to be kept to a minimum.

 

[Electroman]

RM - Rated Miles.

For M3LR it is 310 miles and M3SR it is 220 miles

 

[Polly Wog]

I make many trips from Kihei, Maui (sea level) to the summit of Haleakala (10,000 ft) and back, and I can say that the Model 3 LR can definitely do better than what Tesla advertises. On a recent round-trip, I used 85 rated miles to go 99.3 actual miles. This is not an abnormal experience, either, as I can replicate it at will for that drive. Yes, I'm not going 70+ MPH, but to climb to 10,000 ft and get this kind of range round-trip is still impressive.

 

[Reid]

I make many trips from Kihei, Maui (sea level) to the summit of Haleakala (10,000 ft) and back, and I can say that the Model 3 LR can definitely do better than what Tesla advertises. On a recent round-trip, I used 85 rated miles to go 99.3 actual miles. This is not an abnormal experience, either, as I can replicate it at will for that drive. Yes, I'm not going 70+ MPH, but to climb to 10,000 ft and get this kind of range round-trip is still impressive.

Good to know. My best tank of gas in my previous (turbo) car was going up and down a similar altitude, but at speed, so it's definitely doable even on an ICE and with no regen. From a little trial and error across multiple vehicles, the worst one was my wife's Subaru which has a 4 speed auto so it spends a lot of time hunting for gears and in (presumably) inefficient areas of the powerband. More powerful motors with more gears do a LOT better in the hills and seem to suffer no mileage penalty (as long as you're not doing a net uphill of course!)

Speed is what kills range, I think this morning I saw 340Wh/mi. Yikes.

 

[Reid]

On my commute, doing >300Wh/mi has been somewhat surprising. I was thinking the 240Wh/mi rating on the car was *extremely* optimistic.

But then I took my first "roadtrip" in the car (okay, it was only like 300mi in one day) and I got almost exactly 240Wh/mi. I'm very impressed. From the Bay Area, drove out to Granite Bay (east of Sacramento) and back. Almost entirely on I-80. Hit some slowdowns and stop-and-go in Vacaville and the usual disaster areas, but mostly cruised at 80-85mph and was amazed to get the rated range. I was thinking 240Wh/mi was only achievable setting the cruise control at 58mph and leaving the A/C off or something. Not so!