Out of juice - battery issue, UI issue, or user mistake?

[MichFin]

I went on a road trip in my friends Buick in the Upper Peninsula of Michigan and he was freaking out because he had only 100 miles left and 20 miles to the next gas station. This is not exclusive to electric cars.

NEVER TRUST THE MILE RANGE IN ANY CAR.

Also, when in doubt slow down. Because at 45 MPH your range is much longer than at 70.

http://www.wired.com/images_blogs/autopia/2012/05/graph1.jpg

 

[ecarfan]

Sorry to hear about your wife's experience.
Even though you have been able to drive "below 0" you are incorrect in believing that the Model S has a reliable, designed in "reserve" like ICE cars do. It does not and many posts over the years at TMC demonstrate that.
Slowing down from 70 to 60 or 55mph significantly increases range. This is also true in ICE cars.
The displayed rated range is only an estimate, not an absolute. It is important to use the energy prediction graph. I have found it to be very helpful and remarkably accurate.

 

[Panoz]

Not an owner, but isn't the point of the thread that the rated miles display was waaaay off? If the user can see the miles dropping far in excess of the rated miles, shouldn't the software take into account the actual consumption of energy and adjust the display? It is a significant issue of the rated miles is as far off as the original post says it was. Such an experience would certainly give permanent range anxiety to most folks.

I just don't understand - if the car knows it's about to die (warnings of imminent outage were given), and the rated miles is still showing range, why can't the car adjust the rated range?

 

[FlasherZ]

Not an owner, but isn't the point of the thread that the rated miles display was waaaay off? If the user can see the miles dropping far in excess of the rated miles, shouldn't the software take into account the actual consumption of energy and adjust the display? It is a significant issue of the rated miles is as far off as the original post says it was. Such an experience would certainly give permanent range anxiety to most folks.

I just don't understand - if the car knows it's about to die (warnings of imminent outage were given), and the rated miles is still showing range, why can't the car adjust the rated range?

"Rated miles range" is a complex equation - it's impossible for the car to know exactly how far the batteries can be driven. The car does a reasonable job of estimating it in most circumstances.

When you are nearing the bottom of the charge, the voltage begins to drop very dramatically. The car has a specific cut-off point at which it shuts down, and it must do that. For cars that don't often make it to the bottom of their range, the software doesn't have enough data points to do the extrapolation.

Even if the car did adjust it, at mid-to-highway speeds you're likely to see the miles range drop off just as fast as you can count them verbally, so you would have the same problem anyway: you'd be on the side of the road wondering why it showed "4-3-2-1-0-CHARGE NOW" in a matter of 5 seconds.

This doesn't typically happen unless you're in the single-digits of rated range. Like an ICE that has rested its gauge on the "E" peg, you really don't know when that fuel pickup will grab air.

 

[ecarfan]

Not an owner, but isn't the point of the thread that the rated miles display was waaaay off? If the user can see the miles dropping far in excess of the rated miles, shouldn't the software take into account the actual consumption of energy and adjust the display? It is a significant issue of the rated miles is as far off as the original post says it was. Such an experience would certainly give permanent range anxiety to most folks.

It may seem that way to those who are not owners and have not lived with a Tesla for awhile, but in real life "range anxiety" is not a significant issue with the Model S, in my opinion. The Rated Miles display is useful but owners quickly learn that it is not the only bit of information that the driver should pay attention to. The energy prediction graph is very important and very useful. And it is easy to understand once you have used it.

 

[Rocky_H]

It may seem that way to those who are not owners and have not lived with a Tesla for awhile, but in real life "range anxiety" is not a significant issue with the Model S, in my opinion. The Rated Miles display is useful but owners quickly learn that it is not the only bit of information that the driver should pay attention to. The energy prediction graph is very important and very useful. And it is easy to understand once you have used it.

Yes, besides just the “Trip” tab, I use the main consumption line graph page of that energy app. It will show a projection of real miles left that you can go based on the consumption rate of your current driving style/conditions. I compare that to the remaining miles in nav to keep some of an eye on the buffer left. That is basically like the “Trip” graph showing percent remaining at the end, but I think more in miles than percents.

 

[ckessel]

She had only 2 miles to the Supercharger and the car had several miles of range on the meter.
...
Ellen now has zero faith in this car for road trips.

Well...s*#*.

Been an owner since Dec 2012 and didn't have any range anxiety until now. I just lost a ton of faith in my car after reading this. I certainly am well acquainted with real world vs. rated and I plan accordingly, but I depend on the car telling me the range left!. I've gotten under 20 miles of range several times when usage and/or conditions ate significantly into that buffer.

If the range says 0, but there's some left, that's ok. It is absolutely NOT ok to die before reaching zero. Tesla should set that algorithm accordingly for the worst case!

Now I'm going to be seriously paranoid on every road trip, worried if this is the one time the range meter is going to be woefully inaccurate?

There are gas stations every few miles and I can pull over at nearly any time, consequently the gas gauge has the luxury of being inaccurate. That's not true for EVs and super chargers.

 

[mknox]

Yes, besides just the “Trip” tab, I use the main consumption line graph page of that energy app. It will show a projection of real miles left that you can go based on the consumption rate of your current driving style/conditions. I compare that to the remaining miles in nav to keep some of an eye on the buffer left. That is basically like the “Trip” graph showing percent remaining at the end, but I think more in miles than percents.

I do the same on trips where I'm uncertain. Nav shows me how many "actual" miles I have to go, and the Trip tab on the Energy Display shows how many the car is projecting I will get. I would never let the difference between Actual and Projected get anywhere near zero personally.

- - - Updated - - -

Now I'm going to be seriously paranoid on every road trip, worried if this is the one time the range meter is going to be woefully inaccurate

The Range Meter, whether you have it set to Rated or Ideal really needs to be treated like a gas gauge. You need to use the car's Trip estimator to get a sense of how far you can still go.

 

[wk057]

I've done multiple trips to single-digit rated miles remaining and have not (yet) been stranded. However, each time I did I always started out from 100% charge. This helps the car with knowing how much power is available and tunes the rated miles display.

Also, once you get below a certain point the car will start limiting power as evident by the dashed yellow line. I always watch closely once this appears because it is based on the amperage allowed from the pack. If it gets too low the car will shut down regardless of what the range display says. Fortunately mine has always been pretty accurate.

You'll see I have something like 200kW of power available still, even though I have 2 rated miles left, meaning the gauge was fairly accurate. If needed would the car have let me drive a little past zero in this case..... maybe, given that I've seen the dashed yellow line much lower in other posts here.

In this post from this thread the dashed yellow line is below 80kW! That's near or at the-battery-is-going-to-be-damaged-for-good territory and I would have voluntarily pulled over well before this point even if it meant not making it to where I had to go...

 

[FlasherZ]

If the range says 0, but there's some left, that's ok. It is absolutely NOT ok to die before reaching zero. Tesla should set that algorithm accordingly for the worst case!

Let's assume that right now, 95% of the time the range indication is going to be on target or better, with 5% of the time being an issue in the single-digits (I'm guessing the accuracy is higher than this if we were to do some measurements, but let's use 5%).

So let's play this out a bit. Tesla "sets the algorithm accordingly for the worst case" - in essence, they're going to shift the rated range to the left. That would create the "buffer" for 95% of the people, and over time people will learn that zero doesn't mean zero. It will result in more people trying to stretch to that buffer, and more cars left shut down on the side of the road (rather than less). You can try to blame the driver, but I will disagree with that, only because it will be a "known fact" that there is an extra reserve.

It is in Tesla's best interests to make that as accurate as possible, rather than being overly conservative, given the fixed capacity of battery packs. If we see a battery breakthrough that gets us double the range, or the coverage becomes better, then we can worry about whether Tesla could build in some extra capacity.

 

[mspohr]

Well...s*#*.

Been an owner since Dec 2012 and didn't have any range anxiety until now. I just lost a ton of faith in my car after reading this. I certainly am well acquainted with real world vs. rated and I plan accordingly, but I depend on the car telling me the range left!. I've gotten under 20 miles of range several times when usage and/or conditions ate significantly into that buffer.

If the range says 0, but there's some left, that's ok. It is absolutely NOT ok to die before reaching zero. Tesla should set that algorithm accordingly for the worst case!

Now I'm going to be seriously paranoid on every road trip, worried if this is the one time the range meter is going to be woefully inaccurate?

There are gas stations every few miles and I can pull over at nearly any time, consequently the gas gauge has the luxury of being inaccurate. That's not true for EVs and super chargers.

Don't panic!
As many people have said in this thread, the indicated range on the speedometer is only an estimate and you should not rely on it (especially when it is close to 0).
However, the Tesla does have a very accurate range prediction algorithm built into the Nav system. I use this whenever I am on a long trip where I am concerned about having enough range to reach the next charge.
Set your destination in the Nav system and then call up the "Energy" graph (center bar graph icon on screen). This gives you a graph of the projected energy use during your trip. This graph takes into account your speed, temperature, elevation (and probably a bunch other stuff) and it is updated continuously to adjust for your driving.

The graph will tell you (with a high degree of accuracy) the range you have. It adjusts as you drive so that if, for instance, you go faster, your range will drop and you can see your original range as a grey bar and your new range on the graph. The graph turns yellow and red if you are going to be low at the end of your trip. If it looks like you are going to not have enough range, slow down and the graph will turn up.
In short, do not rely on the range indicated on the speedometer. It is only a rough estimate. Use the Energy graph from the Nav system. It is very accurate and adjusts continuously.

 

[Max*]

Yeah, I already brought that up, I suspect he didn't use the trip tab: Out of juice - battery issue, UI issue, or user mistake? - Page 5

 

[mknox]

This gives you a graph of the projected energy use during your trip. This graph takes into account your speed, temperature, elevation (and probably a bunch other stuff) and it is updated continuously to adjust for your driving.

Not to put too fine a point on it, but I don't believe it factors temperature. Last winter, no matter what I did, I couldn't come even close to the projected line even if I pre-heated the car on shore power and drove below the speed limit. Especially on shorter trips. In the summer, I can easily keep my green "Actual" line at or above the grey "Projected" line. Just a word of caution as we will be in the cold months before you know it.

 

[ckessel]

The graph will tell you (with a high degree of accuracy) the range you have.
...
In short, do not rely on the range indicated on the speedometer. It is only a rough estimate. Use the Energy graph from the Nav system. It is very accurate and adjusts continuously.

So, you're saying the graph knows with a high degree of accuracy the range I have left. But the rated range on the speedometer doesn't? That'd be pretty mind numbingly silly given both systems rely on the same underlying battery readings to make their calculations.

And sort of beside the point. The car died with > 0 miles showing. That shouldn't happen. If that means Tesla tweaks their algorithms to be conservative in showing rated range, so be it.

If it says I've got 20 miles left and it's 5 miles to the SC, I should feel free to drive like a mad man with 4x the range I need. I shouldn't have to drive 40mph in the slow lane praying that this isn't the time the rated range is seriously wrong.

 

[Max*]

So, you're saying the graph knows with a high degree of accuracy the range I have left. But the rated range on the speedometer doesn't? That'd be pretty mind numbingly silly given both systems rely on the same underlying battery readings to make their calculations.

The graph takes account elevantion on your path. If you're going downhill for 20 miles and then uphill for 20 miles, your RR will start to go up first and then down, but the graph will look like an upside down letter V (someone actually posted one). And predict your RR at the end of your 40 mile trip much better than your RR on the speedometer.

So yes, the graph knows a lot better.

 

[dsm363]

So, you're saying the graph knows with a high degree of accuracy the range I have left. But the rated range on the speedometer doesn't? That'd be pretty mind numbingly silly given both systems rely on the same underlying battery readings to make their calculations.

And sort of beside the point. The car died with > 0 miles showing. That shouldn't happen. If that means Tesla tweaks their algorithms to be conservative in showing rated range, so be it.

If it says I've got 20 miles left and it's 5 miles to the SC, I should feel free to drive like a mad man with 4x the range I need. I shouldn't have to drive 40mp in the slow lane praying that this isn't the time the rated range is lying to me.

The range on the is based on a fixed Wh/mile I thought. Use it more of like a gas gauge or switch to percentage instead. A gas gauge doesn't tell you anything more than how much fuel you have, not how far you can go. If you want to use rated range keep an eye on the buffer you have over your distance to destination. If that delta shrinks quickly then you need to slow down or do something else different.

 

[Cyclone]

The range on the is based on a fixed Wh/mile I thought. Use it more of like a gas gauge or switch to percentage instead. A gas gauge doesn't tell you anything more than how much fuel you have, not how far you can go. If you want to use rated range keep an eye on the buffer you have over your distance to destination. If that delta shrinks quickly then you need to slow down or do something else different.

Exactly! I really wish that the Projected Range from the Energy app (even with the Nav's Trip Projected Range) was available to as an option over Rated Range (so I'm always estimating based on last 30 miles) and allow when a Nav destination is programmed in to use that Projected Range on the speedo instead of any other number.

And, of course, make this user-selectable for those who do not like these #s.

 

[Max*]

And, of course, make this user-selectable for those who do not like these #s.

This is key.

I use the RR more as a percentage gauge (not sure why I don't just switch to percent), and use the trip estimates whenever I'm worried about actual range.

 

[ckessel]

The graph takes account elevantion on your path. If you're going downhill for 20 miles and then uphill for 20 miles, your RR will start to go up first and then down, but the graph will look like an upside down letter V (someone actually posted one). And predict your RR at the end of your 40 mile trip much better than your RR on the speedometer.

So yes, the graph knows a lot better.

It knows better what your energy usage profile looks like, but it doesn't know any better what the energy remaining is.

The problem is the car shut down well before reaching a range of zero. Doesn't matter if you looked at a ranged range of 20 or a graph range of 10 if it's really zero and both are fed the same bogus data from the battery system.

 

[mspohr]

The range on the is based on a fixed Wh/mile I thought. Use it more of like a gas gauge or switch to percentage instead. A gas gauge doesn't tell you anything more than how much fuel you have, not how far you can go. If you want to use rated range keep an eye on the buffer you have over your distance to destination. If that delta shrinks quickly then you need to slow down or do something else different.

It's probably best to switch the speedometer range display to show "percentage" rather than miles (this is a controls option you can set). This should eliminate confusion and make it more analogous to an ICE car fuel gauge which also shows percentage full (and not range).