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Range Failure
- Thread starter gnuarm
- Start date
IdaX
Member
5% in particular is a dangerous number. If you were, say, slightly below 5% under normal expectations, sometimes the nav will “helpfully” assume that you’ll slow down and then give you that 5% number again. To show this, enter a destination that’s beyond your range right before you supercharge. Hit “continue trip”. Then bring up the trip graph. As you supercharge, once the projected arrival battery percentage gets to 5%, it stays there for awhile while the usage curve steepens. Then once it’s done steepening fully (as it assumes faster and faster driving speeds for the trip) the percent increases again beyond 5%.
TL;DR: 6% is actually way, way safer than 5% — much more than 1% more margin.
I guess I wasn't really that clear. To return to the NoVa to Joyce Kilmer example: I would tell ABRP that I wanted to arrive at Joyce Kilmer with 20% reserve and that the nominal consumption was 102000/295/.8 = 432 Wh/mi. as that's what the median X driver realizes. It would tell me to stop at Newark, DE and charge for 12 min. I'd check the METARs for BAL and DOV and see that the winds are from the E and ESE and, knowing that I've been seeing consumptions more like 310 than 432 think I would have a pretty good chance of making it to East Brunswick without a stop. And the car doesn't advise a stop. It just says that I'll get to East Brunswick with 8% reserve. But I've done my homework and I know how to interpret the information available to me. If I see my consumption rising into the 400's I'll be on alert and probably stop at Newark DE (or at any of the other available SC's of which there are several though they would require getting off I95).
So yes, I am gambling. The bet is that I can make it all the way to E Brunswick without recharging AND be able to recharge there. But I have lots of backups if it looks as if I'm not going to make it there or if the SC there is failed. As is usual, there is a trade space. The desire to spend the minimum time at chargers (realized by stopping as seldom as possible and by arriving with a low battery) must be traded against the likely risks. What life is really about these days is dealing with uncertainty while remaining comfortable about it.
I've mentioned before that I am an engineer (retired) and used to fly airplanes. Thus I have no range anxiety as I've dealt with this problem before. And I have run low on fuel in airplanes (and in ICE cars) before but I learned from those experiences.
Would I pass a SC with 12% estimated destination battery if I had 36 miles to go? That would depend, among other things, such as whether the trip was over roads I'd traveled before or not, on the current charge. If I had 24% indicated an estimated arrival at 12% tells me I'm going to be burning 333 Whr/mi. That's pretty reasonable but I'd probably do the calculation with 500 as it's easy to multiply 500*36 and conclude that I'd be using 18 kWh and arrive with 6% margin if things got as bad as 500 Wh/mi. As doing worse that 500 Wh/mi is unlikely I might be tempted to go for it though I have always been a belt and suspenders type of guy and would probably stop and do the extra charge.
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Doesn't matter. It showed 12%, so it's 12%. It's a continually updating estimate based on the amount of energy it has now and what it shows coming up on the rest of the drive. So you can count any point like that as if it's a new starting point with a 12% estimate. It doesn't matter how it used to be--if that 5% or 0%. That is in the past and is not part of how the estimate is calculated anymore. I've departed with a -3% estimate before and drove extra slowly to get it up to 14% over the first 50 miles or so, and then was able to manage it normally the rest of the way, keeping it in the teens.
I have disagreed with @gnuarm strongly on several of his threads from a long history of dramatic hand-wringing over nonsense, but in this case, I think he seems to be right. 60-some degrees after driving more than 100 miles certainly isn't cold at all. And when going onto slower speed roads of the 45-55 mph variety, I sure would not expect it to have sudden range dropping problems there.
And it seems like a reasonable thing where you start off driving with a tight estimate, knowing that there is a Supercharger along the way to see if you would need to cut short to charge there or have conserved enough to get a higher range projection and may be able to pass it up. I would usually prefer to go with 20%, rather than teens in an area that is sparse of charging, but teens seems reasonable. (Oh, right, 12 is pre-teen.
)That's what he said. He is not bothered by having to learn the details. You're thinking of the phrase, "I can't be bothered to learn the details." That means the opposite.
GHammer
Dark Star
It's you that continue to argue points that you don't know about and aren't reading others posts. I never said the battery temperature was an issue. The trip estimator does not take battery or ambient temperature or wind or pavement condition into account, only the expected speed and elevation are used. Air changes in density with temperature, 60 degree air is more dense than 85 degree air which contributes to range losses at 60 vs. 85.
I'm not arguing with you that something happened to your trip estimation on this particular trip but it is not a widespread issue and you are being far too dramatic about it. I have road tripped far more than you have and have never seen a huge unexplained loss in final SOC. It's not a wonder you have so many thumbs down ratings.
That's what I mean. I don't mind learning the details. However, trying to plan a trip with a bunch of calculations is pretty much BS.
Next time my trip requires much off highway driving, I'll make sure I'm all charged up before I go on back roads.
Wow! This is what I run into on these discussions. People bring up minutia and try to talk about these things as if they were real factors.
First, if the estimator doesn't consider battery temperature directly, it will factor it in when it sees the battery state of charge dropping on the initial 150 miles faster than expected. If it doesn't factor in your actual usage, then it can't adjust the remaining charge estimate.
Second, the difference between 60 and 85 degree air temperature has to be way down the list of things that impact range when driving on secondary roads at very reduced speeds which is where I saw the remaining charge estimate drop. Besides, as I drove, the temperature continually increased which should have increased my range estimate.
I am reading everything people write. I am pretty sure they aren't reading everything I write.
The bottom line is this is the first time I've seen such a huge drop in estimated range from this car. Going from 12% to -2% is not what I consider unimportant. It is useful to know this is not unexpected. One guy who posted about range only had his car for two weeks and his daily commute required him to complete the trip with 1% remaining. Because his remaining charge estimates were always spot on at 1%, he thought it was perfectly ok to go with that. I now know that even 12% is not enough. I just don't have any idea why and no one here has offered any valid ideas as to why it would drop so much. Talking about air temperature isn't at all useful really.
The new estimate is the current SoC minus the product of the distance times the estimated consumption per mile subtracted from the current SoC. Where does the consumption factor come from?
Hint: In the Bolt three numbers are used and the driver gets an "estimated" range, a minimum range and a maximum range.
I assume you are aware that motor efficiency drops at reduced speed.
The mechanism has been explained. You went from conditions with low Wh/mi to conditions with high Wh/mi demand. Thus causes estimated range (and thus margin) to drop. No one has a clue, of course, as to what the cause of this might have been. No one was there.
On planes there are FAA minimum requirements based on time. Enough fuel to get to destination +30 minutes (day VFR). At night it is + 45 min. IFR which is what all airlines fly, enough fuel to reach destination, make an approach, then alternate airport (if required) at normal cruise, plus 45 minutes. Some airlines have additional requirement beyond this.
My wife would hitting me over the head with something if I did not stop with 12% (even 25%) left. And I agree. Ship happens.
GHammer
Dark Star
Geez, why the hostility? I've already said twice I cant explain your situation, everything else I have said has been general advice, not necessarily pertaining to your situation, so that others don't run into a similar situation and become stranded
I'm responding to comments like this...
I have been driving the car for 15,000 miles and been talking about my experiences here for pretty much all of that time. I get every response in the book with some telling me "this" is the way to figure your range and others saying that is a terrible idea and you should always do "that". I'm pretty fed up with so much of it being unsubstantiated and based on anecdote.
I read everything everyone writes. Maybe I misunderstand sometimes, like the graph I had forgotten about. But I really don't see where it gives me any more data than I have using the estimated remaining charge number. Seeing the graph diverge is harder than seeing the number diverge and tells me little more. I suppose it might shed some light on the remaining charge estimate rising early in the trip. But it wouldn't be useful for seeing what to expect.
With the limited range of the cars and the relative paucity of charging in some areas, it is important for the car to reliably predict the range. If EVs are ever going to pan out for the masses they have to deal with the issue so that the typical person won't have to think about it any more than they do now with gas cars. I just spoke to someone while I was charging who appeared to have a negative impression of the whole electric car thing and I think wanted to know about them so he could dissuade his son. I told him the facts rather than sugar coating it. I pointed out that if you aren't taking trips in the car charging at home is the best way and nightly charging is perfectly acceptable. However on trips you have to plan and drive very differently than in an ICE vehicle.
I more than met that requirement. At 12% reserve that gives me 36 miles extra range which is over 45 minutes at the speeds I was driving. If you add in the equivalent of "alternate airport" that would be the next supercharger which is simply not practical. I'd never leave home. That's actually one of my Tesla complaints, that I don't have enough realistic range to skip chargers on many routes in an effort to get a stop with a long charge time so I can eat without wasting time elsewhere to charge. Two 30 minute charging stops is not the same as a single 1 hour stop.
It wasn't 12% LEFT. It was something like 45% left and showing 12% left at the destination. How can the car predict usage of some 33% of the battery turn into using 47% of the battery in the real world? 42% extra energy consumption, that's one crappy estimator.
juliusa
Active Member
Too funny. That is EXACTLY what they told Henry Ford. People will NEVER buy these new fangled contraptions!! Not enough gas stations, not reliable....
You are projecting, my friend. If you read my post you quoted, it said millions ARE getting to their destinations reliably with BEVs. Some are not, just like some run out of gas in their ICE.
Hmmm. Didn't I read that you left the charger with 5% reserve??
Are you a gear head or not? The instrumentation and calculations are for those that want information to do their own calculations - live by the sword, and die by the sword. Trip Planner is available for those that do not - it simply tells you when you have enough charge to reach your destination.
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This is key here, I don't like getting below 10%, but I would never have dreamed to be nervous just because I might get near 10%. The first road trip I even took in a Model X P90D required getting below 10% between superchargers and the only alternatives on plugshare were people's houses. In fact, I got to the supercharger with "11mi" remaining at the end of that trip after driving slow to reach my destination.
He departed with an estimated 5% remaining at the destination. He knew there were superchargers along the way, but he had an estimated 12% remaining at the destination when he chose to bypass them. He has stated this repeatedly. Who is projecting?
Well we certainly don't have as much range as we'd like and that's one of the fundamental limitations of BEV's. Just adding more battery is subject to diminishing returns on range (not to mention the cost). Rivian, for example, is adding 80% more battery to a comparable sized vehicle and getting 33% more range. The real problem is that you don't know how much range you are going to get until you drive the route and get it. Right now my car is 77% charged and has reported estimated range of 331 miles because the last two trips I took consumed, respectively, 288 and 252 Wh/mi (wish it were always like that). I had a tail wind going out and while I was there it shifted to give me a tail wind coming back. Today I could go to the same destination, have a head wind in both directions and pay 400 Wh/mi implying range of 196 miles which us 59% of the current estimated range. Crappy estimator? No, just what the real world physics impose on us.
Generally people are interested in getting to their destination as quickly as possible and the strategy for doing that is more frequent but shorter charging sessions as the car accepts charge faster at lower SoC than it does when closer to being full. This also benefits the network as cars are in the stalls for less time. But if you want to stop longer for a meal that's easily done. Just ask the car to charge to 90% (or even more but don't do this at a busy charger). I have suggested before that you play with A Better Route Planner. If you do that enough you should be able to come to understand the relationships between the various parameters, learn how to plan routes and better understand the in-car displays.
That happens when the per mile energy demand of the car as estimated from the recent driving history increases by 42% as you encounter new driving conditions.
Actually it is doing exactly what I and the others here who understand what it is doing would want it to do. As you aren't able to grasp that perhaps it would be better to step back a bit and look at the forest rather than the trees. Were it really a crappy estimator there would be many people here who agree with your assessment, Tesla would be inundated with complaints and the "crappy" estimator would be removed or repaired.
I think you are just going to have to accept that these graphs/displays may not be accessible to you. That's OK. My wife has no idea what they mean either and she still enjoys the car. Perhaps those who advised you to ignore them realized this from your previous posts. Perhaps you could just think of the SoC indicator as a gas gauge. There is, of course, one problem with this and that is that the refueling stations here are much farther apart than actual gas stations so while you might, in an ICE, wait until the little red light comes on, in this car you had probably better start thinking about charging when it dips below 40%. You should, in any case, know where reliable (and right now that essentially, as you found out, means Tesla) chargers are along your route.
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