Failed range calculation left me stranded

[Tiger]

Wow. A hyper-defensive, sarcastic set of responses. I am shocked.

Not shocked about that, you are kind of nitpicking, but, nevertheless, it's something that Tesla could improve. Like the Boring Company says, "if there's something we could do better, we ask the public to let us know and we will try to improve". Tesla should do that too, wouldn't it be fun if Tesla had a public RFE list where you could vote for features if you currently own a Tesla and Tesla could prioritize/schedule and respond/comment/suggest workarounds.

The range calculation should always be an underestimation. End of story.

In an ideal world, yes, I agree. But would you drive an ICE with 8 miles left? Nope, because variations in inclination of the car might cause that petrol (if very low) cannot be successfully delivered to the engine and your journey ends. I believe estimating the final miles of an electric car could be similar, very granular and very unpredictable. Anyways, I agree that it probably can technically be solved, to give a coarse underestimate of the remaining mileage, after reaching a certain level, say after 30 miles remaining. It would simply be very kind for the stupid human driver who is anyways lazy and distracted and trying to push the limits at the end of his/her journey.

 

[Graffi]

True Story in a GAS car:

I borrowed my Mom's car to move away from home for the first week of college, about 72 miles from home. On Friday I thought of getting some more gas at the start of the trip but thought I could make it. If not, I could stop anywhere along the route, as there were small towns or communities every 5 or 10 miles.

Anyway, as the gas gauge reached about 1/8th tank it did not move. I just thought I was getting great gas mileage. I was not overly worried, but looked at it every once in a while.

As luck would have it, with 1/8th of a tank the car died. I was about mid-way between gas stations, about 2 miles each way. This was in 1969, in rural south Georgia, so it did not take long for an old pick-up to stop for a held out thumb.

Long story short, I got a ride to the next gas station, they loaned me a gas can, got another ride back to my car, then was able to drive to that gas station to fill up the tank.

When I got home my Dad was able to let me know that "the gas gauge gets stuck at 1/8th tank so always fill up when it gets below 1/4 tank." Gee thanks, Dad. You could have told me before I borrowed the car for the week. I guess that since I had been driving this car off and on for a couple of years he thought I knew.

Well guess what, I did not blame the car, or my Dad, for that matter. It was a lesson I needed to learn.

Twice now I have had to slow down on my cross-country Supercharger trips, to make sure I got to the next Supercharger station. I always build in a safety margin, and watch the remaining energy. Even if I did not, the car tells me to reduce my speed to have the range to arrive. If I do drive the car until it shuts down, it will "be my own D**** fault!" (I was reminded of a country song as I was writing this.)

 

[Raechris]

That sure is a frustrating experience. I have had this happen with my PHEV vehicles testing their “guess-o-meters” as they switched to gas. Were you running AC at 76F or had windows open at speed toward the end? Was the display set for miles or percentage? If miles, rated or ideal?
The algorithm behind the display does the best it can, but as OPs have indicated, every fuel gauge has the same issue at the end of the “tank”. At least we don’t worry about hills and gas being at the wrong end of the tank anymore.

 

[cwerdna]

First I've heard of a Tesla shutting down before the zero. We know not to trust the listed range, but I too would have assumed a listed range of 6 miles would have been enough to cover 2.5 miles. I.e. if I was 2.5 miles from home and my range said 6 miles, and there was a L2 charger a block away, I would not stop to charge.

It is not my first. Besides Bjorn's story, I heard about what's mentioned at Tales from a Tesla Model S at 200k miles from Sep 2016:

Then, just as the car hit 200,000 miles, the range estimator became inaccurate. Though the car didn’t actually lose any range, the estimator would say it could go another ten miles—and then power down. Tesla looked into the issue, and told Tesloop that there’s a battery chemistry state that high-mileage cars go into, and the software isn’t properly compensating for that change. There will be a firmware update in three months that will take care of the discrepancy, but Tesla just replaced the battery to solve the problem

FWIW, on Leaf, at the 2nd low battery warning aka Very Low Battery Warning (aka VLBW), the (crap) guess-o-meter turns to - - - miles. On 2013+ Leafs, which finally included a % state of charge display, at some point when it's low, it'll also change to ---%. I had mine go from 5 or 6% SoC to ---% SoC (Estimated Range Dropped to Zero All of a Sudden - My Nissan Leaf Forum) before I had Leaf Spy. Now I have Leaf Spy and still have visibility as to what's going on and how close I am to dead when my GOM AND my % SoC have changed to ---.

When Leaf was new, Edmunds drove an '11 Leaf until totally dead. Video is at Driving It To The Bitter End - 2011 Nissan Leaf Long-Term Road Test. That car had no % SoC display yet.

At about 1:30 into the video, they hit VLBW and their GOM changed from 11 miles to --- miles. They were 122 miles into their test. They kept going and their car came to a halt at 132.0 miles.

 

[dethman]

Wow. A hyper-defensive, sarcastic set of responses. I am shocked.

The range calculation should always be an underestimation. End of story.

yeah i know, shocking. it seems to be the common trend around here when anyone says anything remotely negative about a tesla. as if there is nothing that tesla could possibly improve on.

 

[widodh]

Again, this is the first time I’ve seen a post about a Tesla shutting down above zero (have there been others?). So it’s a useful PSA type learning experience worth sharing among the Tesla community. I can’t be the only person that would have thought the same as the OP in this scenario. Now I know differently. Learn something new every day on these forums.

It might happen as well when you suddenly have to go uphill with a very low SoC or you accelerate hard with a super low SoC.

The voltage then drops in the battery and might cause the car to shut down.

I just never run it below 30km, I'll charge before it hits that mark. A few minutes at a charger should be sufficient.

So I am on my way home with a reasonable amount of range in excess of my destination (home). Not excessively hot, dusk, normal driving conditions. I have roughly 6 miles of range left for my 2.5 miles remaining when I get a warning that the vehicle is shutting down, and I end up stranded 1.4 miles from home with 4 miles of range reading. Outside temp 76F. How is this not an error on the vehicle's part? I get that you cannot rely on there being excess range after zero, but now you cannot trust that the range provided is accurate?! How can one trust the vehicle at all? I am no stranger to dealing with these cars, and have put over 100K miles between our Model S and Model X, but in my opinion the inability of the car to accurately represent it's remaining range is unforgivable. I hope that Porsche does it better, because Tesla just lost a former fanboy.

Can you tell a bit about the last few miles? Was it uphill? Did you accelerate hard (or tried to)?

What happened is that the voltage in one or more cells dropped below a safety threshold and caused the shut down.

Personally I would never run it that low, not even with my ICE, but that's your choice.

 

[S4WRXTTCS]

Out of all the battery powered devices I have the Tesla is easily the best at telling me how much is left.

Sure it's not 100% accurate, but it's certainly better than anything else I've tried.

Can you imagine if Apple made an electric car?

Everything would be fine, but then suddenly for no reason at all you'd lose 40% of your battery range.

 

[kiwi]

I'm in the camp where my butt is puckering something awful when the fuel tank shows
< 20% - be it a petrol car, my wife's Leaf or my Tesla. I know they all have different
range left, and usually quite a lot... its just something psychological about that empty looking tank.

 

[Exiom]

yeah i know, shocking. it seems to be the common trend around here when anyone says anything remotely negative about a tesla. as if there is nothing that tesla could possibly improve on.

I mean... If it was a complaint about a genuine issue... I am sure most people would react differently...

But when you post about something that is obviously not very bright... and then have a hissy fit about it then blaming it on the car and how you will go buy another car... well... you are asking for it...

This has always been an issue with batteries... it's never accurate... and like I said before... I am sure you have had an electronic device shutdown on you before it said 0% or that it has a sudden drop in level... I am sure Tesla can "improve" it by adding in a safe guard and faking 0... and then you will see posts complaining about how their cars got sudden battery degradation...

 

[logan]

Wow. A hyper-defensive, sarcastic set of responses. I am shocked.

The range calculation should always be an underestimation. End of story.

What do you expect from people who have had a bit too much Tesla Kool-Aid?

 

[kingjamez]

How fast were you driving when it died?

Lithium battery capacity is very difficult to judge when the state of charge is low. The voltage starts to drop off a cliff at the end and the lowest bank of cells determines where the cutoff is. Additionally, the discharge rate of the cells determines how fast the voltage curve drops / sags.

At the last few percentage points, simply having a quick acceleration (even from a stop) can be enough to sag the voltage to the cutoff level where if you had kept a steady pace you'd have gotten the full rated range.

The C rating represents discharging the pack completely in 1 hour. Tesla batteries average roughly .3C on the highway, but if you accelerate you can hit 1-2C easily, see how the voltage sags when that happens?

-Jim

 

[ItsNotAboutTheMoney]

Wow. A hyper-defensive, sarcastic set of responses. I am shocked.

The range calculation should always be an underestimation. End of story.

Why didn't you deduct whatever underestimation you want yourself?

 

[trm2]

The OP made a decision based on the best available information. It turned out that the information wasn't very good. Quite a few of us will use additional information (e.g. I'm not comfortable pushing it that close) and make a different decision, but now he knows.

 

[mltv]

Wow. that is a much better estimation than my f*** iPhone

 

[RyanDe]

I hope that Porsche does it better, because Tesla just lost a former fanboy.

I ran my F-150 out of gas, hope Chevy handles is better. Hilarious first world problem, thanks for making me laugh this morning.

 

[Sharpgt]

I can understand the frustration of the poster and perhaps Tesla needs to recalibrate its estimated remaining mileage gauge BUT does one unhappy event undo 100K miles of driving nirvana? I am a huge Porsche fan, have owned well over 20 in my lifetime and currently have 2. I am on the list for a Mission but do not expect it to be more reliable or more accurate than either of my Teslas.

 

[artsci]

Again, this is the first time I’ve seen a post about a Tesla shutting down above zero (have there been others?). So it’s a useful PSA type learning experience worth sharing among the Tesla community. I can’t be the only person that would have thought the same as the OP in this scenario. Now I know differently. Learn something new every day on these forums.

Agree, and I think a number of comments have been at bit over the top on @Twiddler. I realize that the range estimations are not perfect but there should be some margin to prevent this kind of thing from happening. Several times I’ve gotten down to 6 miles, and not by choice. I’ve always assumed that the estimates had some safety valve. Based on Twiddler’s experience that assumption might lead to trouble.

 

[rpo]

My cell phone consistently shuts off with 7 to 20% battery remaining a moment before it suddenly is not on anymore. I do expect larger battery packs (such as one in a Tesla) to be more accurate, but you still risk it suddenly hitting that low voltage limit due to things outside your control. I've never had it happen with 75k miles driven so far, but also haven't gone under 3% remaining in the last 50k miles to test the actual limit.

 

[GregRF]

I have roughly 6 miles of range left for my 2.5 miles remaining when I get a warning that the vehicle is shutting down, and I end up stranded 1.4 miles from home with 4 miles of range reading.

When was the last time you charged the car to a high level (>95%)?

I believe that is when the battery is able to do a re-balancing and probably give a better estimate of energy storage.

 

[commasign]

Agree, and I think a number of comments have been at bit over the top on @Twiddler. I realize that the range estimations are not perfect but there should be some margin to prevent this kind of thing from happening. Several times I’ve gotten down to 6 miles, and not by choice. I’ve always assumed that the estimates had some safety valve. Based on Twiddler’s experience that assumption might lead to trouble.

Agreed. I'm not worried about those of us on the forums cause we're a weird bunch. I'm worried about mass market adoption of EVs. From that point of view, I agree with the OP that Tesla should have designed the guess-o-meter to be even more conservative at the bottom, or at least put some warning messages when it can no longer provide a guess (or implement whatever software changes were hinted at regarding high mileage battery chemistry). Or at least mention in the manual that below X miles, the remaining range may be inaccurate. All of us here get that now, but what about everyone else? The average new EV owner may not immediately make the connection that their EV battery could behave similarly to their smartphone battery with regard to suddenly shutting down even when remaining charge is estimated to be above 0%.