built in exta mileage with in the battery?

[David99]

... , it was determined that the car shut down early because it predicted that it could not sustain the current speed (70mph) with the amount of charge left on the battery (whatever equates to 4 rated miles).

While it is frustrating, there is no way the car can predict your upcoming driving style and energy usage, thus a prediction of how many miles are left is always guesswork. It also shows one disadvantage of batteries vs gasoline. An ICE engine can run fine and at full power all the way to the moment you run out of gas. A battery is more like a human. It gets weaker and weaker. Especially towards the end it is a good idea to go easy. Reduce speed and limit acceleration. If you go easy on the battery it will give you more at the end. Your experience confirms that. I went easy towards the end and was able to get beyond 0 a few times.

I don't care where the danger zone is; just tell us where to be concerned. It could be below 10 rated miles, below 0, or even below -10, but Tesla should just tell us at what point to be worried, and not change the "danger region".

They do. At 50 miles left the battery bar changes from green to yellow, then to red at 30 miles. Red = danger zone. red = be concerned. Having less than 10 miles left and gunning it uphill at 70 mph = pushing it.

 

[apacheguy]

I wish this were the case. I just hit 30K miles on my 60. Woohoo. Unfortunately I had my first experience with running out of juice on a busy freeway. Not a fun lesson. I've driven between Harris Ranch and Tejon Ranch several times, and I knew there was a slight elevation gain just before reaching the superchargers at Tejon. What I had not taken into consideration this time was the new version of firmware installed on the car. So literally about 1000ft before the exit and with 4 rated miles shows on the dashboard, my car shutdown. And it was fast (about 30 seconds). I was lucky that I pulled over to the shoulder of the freeway when I did, because otherwise I might have been in a quite a bit of trouble.

Double take, what?! The car shut down while it was still showing range? This is simply unacceptable, IMO. Below 0 anything is fair game, but above 0 I don't care what some stupid algorithm is saying. This does not instill a great deal confidence. I have arrived twice before at a SpC where it was close (<10 miles showing), but I knew I would make it both times because I trusted the range numbers and calculated that I would make it before hitting zero.

While it is frustrating, there is no way the car can predict your upcoming driving style and energy usage, thus a prediction of how many miles are left is always guesswork.

Disagree. It knows the pack voltage and it knows the trigger for flipping the battery contactors. This is a precise measurement. No reason to still be displaying range when it knows it has exceeded the threshold.

 

[David99]

Double take, what?! The car shut down while it was still showing range? This is simply unacceptable, IMO. Below 0 anything is fair game, but above 0 I don't care what some stupid algorithm is saying. This does not instill a great deal confidence. I have arrived twice before at a SpC where it was close (<10 miles showing), but I knew I would make it both times because I trusted the range numbers and calculated that I would make it before hitting zero.

Towards the end, the battery is pretty weak. You can either still go for a while driving gently or you can push up a hill at 70 mph and force the voltage drop to a critical value when the car needs to shut down to prevent damage to the battery. There is no way the car can predict your driving style. If you never want this to happen the car will have to assume worst case scenario (uphill fast driving) and subtract the last 20 miles by default. This takes away perfectly usable range for those who drive carefully at the end. Nissan implemented it in their Leaf by switching to 'turtle mode' where the car will only go with very limited power to keep the battery safe yet allow you to use the last little bit of juice.

 

[bollar]

Nissan implemented it in their Leaf by switching to 'turtle mode' where the car will only go with very limited power to keep the battery safe yet allow you to use the last little bit of juice.

The Model S also does this, though. Shortly after the battery bar turns red, the maximum power available begins to drop -- to protect the battery, of course. But I also think it should ensure that you don't get an emergency power down with 4 rated miles remaining.

 

[apacheguy]

The Model S also does this, though. Shortly after the battery bar turns red, the maximum power available begins to drop -- to protect the battery, of course. But I also think it should ensure that you don't get an emergency power down with 4 rated miles remaining.

Right, exactly. It's not a question of predicting how far one can go. There's no guess work in play at all. If the car is still displaying rated range > 0, it should not shutdown. Period.

 

[Seattle]

Right, exactly. It's not a question of predicting how far one can go. There's no guess work in play at all. If the car is still displaying rated range > 0, it should not shutdown. Period.

They need to adjust their algorithm to go back to the old system where there was a buffer past 0. These reports are troubling, but I wonder if we have the full story. When you get down close to 0, the available power also reduces. But the old system was better. Why didn't the car reduce the max speed instead of just cutting the driver over?

Not to be mean (no doubt after saying this, I'll run out tomorrow), but I can't imagine trying to drive 70 mph when you are almost at 0. The one time I got almost to 0 I was driving slower, trying to stretch it out.

 

[apacheguy]

Not to be mean (no doubt after saying this, I'll run out tomorrow), but I can't imagine trying to drive 70 mph when you are almost at 0. The one time I got almost to 0 I was driving slower, trying to stretch it out.

@giants01 says he was 1000 ft from the cutoff to the SpC. If I was still showing 4 miles and knew that I only had a couple thousand feet to go, I wouldn't be worrying too much about conserving energy. At that point I'd be thinking "I totally got this."

Agree with your other point that the algorithm should change to allow a small buffer below 0. If we have cars shutting down before they even reach 0, then it's clear that someone was far too aggressive in changing the reserve.

 

[Larry Chanin]

I'm guessing that version 6.0 of the firmware is now adding roughly 5% of rated range in it's current range calculation over previous calculations.

When my Model S was new a full range charge was 265 rated miles. Over time a full range charge dropped to 258 rated miles. Now following version 6.0 my last range charge was 271 rated miles.

If Tesla is now more aggressive in calculating range, it would not surprise me if now there is little or no reserve left when the car displays zero range.

Larry

 

[SarahsDad]

One data point that goes against adding range to the 6.0 firmware is my recent drive from full to empty - used an observed 74.1 kWh on two separate occasions pre-6.0, but this time full to zero yielded only 71.7 kWh. This suggests that there is actually more hidden beneath "0" post-6.0. Or my battery is suddenly losing capacity... Max range charge for all three trips.

Aug 21 2014 (Pre-6.0)

Sept 6 2014 (Pre-6.0)

Oct 24 2014 (Post-6.0)

 

[bonnie]

Hi guys and gals.
Question: does anyone know for sure that there is actually extra miles built in to the battery after the 265 max limit? I had heard that there is a 17 mile bonus that is there in case one takes it to the limit before charging.
True, not true?
thanks
fred z

If anyone tries to convince you that there is a 'bonus' reserve that you can count on, make sure you have their home phone number and an agreement that they'll come pick you up if you dip below 0.

Then you'll see how sure they are that the reserve is something you can count on. (I wouldn't.)

 

[Cottonwood]

If anyone tries to convince you that there is a 'bonus' reserve that you can count on, make sure you have their home phone number and an agreement that they'll come pick you up if you dip below 0.

Then you'll see how sure they are that the reserve is something you can count on. (I wouldn't.)

I don't care how much hidden reserve is there as long as the car will drive reliably down to 0 rated miles. I have gotten very good, in hypermile situations far off the Supercharger Highway, at adjusting my speed and driving style to ensure that I arrive at the next charge location with positive miles in the battery. Mine is a simple request, if the battery indicates 1 or more rated miles present, the car should keep driving, and there should be no sudden jumps in rated miles other than those caused by me using energy to drive, climb hills, heat, etc the car.

What scares me is the report of a Model S stopping when it had a few miles left. If there is uncertainty in the calculation, Tesla should just put all of that uncertainty below 0. If the "hidden" energy is between 17 and 0 rated miles below 0, that's fine, I just want Tesla to put all the required margin below 0, so that I know that the car will continue operation (with reduced power) down to 0 miles.

 

[Larry Chanin]

One data point that goes against adding range to the 6.0 firmware is my recent drive from full to empty - used an observed 74.1 kWh on two separate occasions pre-6.0, but this time full to zero yielded only 71.7 kWh. This suggests that there is actually more hidden beneath "0" post-6.0. Or my battery is suddenly losing capacity... Max range charge for all three trips.

You have driven your Model S to zero on three occassions followed by maximum range charges? Maybe a sudden loss of capacity after the third isn't so far fetched.

Larry

 

[SarahsDad]

I only range charge about once a month. I've driven down to zero almost a dozen times over the last year after a range charge. Total kWh used has always been 73.5 - 74.5 with 0 miles remaining, until this most recent post-6.0 trip. (Curious/obsessed with end-of-charge behavior, but never driven more than 1-2 miles past zero. After reading about the shutdown at 4 miles remaining I might not be so aggressive in the future...)

Still pretty good range charge numbers at 15K miles though...

 

[SmartElectric]

Double take, what?! The car shut down while it was still showing range? This is simply unacceptable, IMO. Below 0 anything is fair game, but above 0 I don't care what some stupid algorithm is saying.

Completely acceptable. Don't drive on empty. Simple.

The Smart ED (and MB B class ED) have a "power meter" which has 3 stages, one each for full power available, then reduced power and finally minimum power available. Depending on the situation it is a good indicator of the estimated stress that can be placed on the battery. In -24C cold soaked for 9 hours last winter, my Smart ED started in minimal power, and warned me that the battery needed to be brought up to temperature before full power could be used. On another occasion when I took it down to zero estimated range remaining, the power indicator dropped to reduced.

People have already reported their P85+ has lower 1/4 mile times as the battery is depleted, so Tesla has the software smarts which could be used to provide a power indicator...

 

[bollar]

Completely acceptable. Don't drive on empty. Simple.

The Smart ED (and MB B class ED) have a "power meter" which has 3 stages, one each for full power available, then reduced power and finally minimum power available. Depending on the situation it is a good indicator of the estimated stress that can be placed on the battery. In -24C cold soaked for 9 hours last winter, my Smart ED started in minimal power, and warned me that the battery needed to be brought up to temperature before full power could be used. On another occasion when I took it down to zero estimated range remaining, the power indicator dropped to reduced.

The Model S also indicates reduced power due to low batteries and cold batteries. For the OP, the car shutdown while indicating 4 miles range remaining, which some of us believe is not desirable.

 

[ecarfan]

When my Model S was new a full range charge was 265 rated miles. Over time a full range charge dropped to 258 rated miles. Now following version 6.0 my last range charge was 271 rated miles.

When new my S85 full charge was 265. Now it is 258 after 10 months and 18K miles. It was 258 a month ago before V6 and it is still 258 after installing V6.

 

[apacheguy]

Completely acceptable. Don't drive on empty. Simple.

Uh, no. NOT acceptable because he was NOT on empty! 4 miles != empty!

What scares me is the report of a Model S stopping when it had a few miles left. If there is uncertainty in the calculation, Tesla should just put all of that uncertainty below 0. If the "hidden" energy is between 17 and 0 rated miles below 0, that's fine, I just want Tesla to put all the required margin below 0, so that I know that the car will continue operation (with reduced power) down to 0 miles.

+1. Exactly.

 

[David99]

... , Tesla should just put all of that uncertainty below 0. If the "hidden" energy is between 17 and 0 rated miles below 0, that's fine, I just want Tesla to put all the required margin below 0, so that I know that the car will continue operation (with reduced power) down to 0 miles.

I agree that is a good idea to make sure people don't get upset, but it would mean they have to very generous in what is left in the battery when it reaches 0 miles. Some driver might want to go pretty fast, so the buffer would have to be big enough to allow for that. The downside is that for everyone who drives normal or even careful at the end, that range would be lost. I would prefer the car to reduce power if necessary ahead of time if there is danger that is won't make it to 0. This way it will make it to 0 as 'promised' without compromising range. That's what I do using my foot and it helped me getting beyond 0 a few times.

I hope soon Tesla will have enough data from cars on the road that it can predict energy needed to reach a destination based on that much more accurate.

 

[scaesare]

I wish this were the case. I just hit 30K miles on my 60. Woohoo. Unfortunately I had my first experience with running out of juice on a busy freeway. Not a fun lesson. I've driven between Harris Ranch and Tejon Ranch several times, and I knew there was a slight elevation gain just before reaching the superchargers at Tejon. What I had not taken into consideration this time was the new version of firmware installed on the car. So literally about 1000ft before the exit and with 4 rated miles shows on the dashboard, my car shutdown. And it was fast (about 30 seconds). I was lucky that I pulled over to the shoulder of the freeway when I did, because otherwise I might have been in a quite a bit of trouble.

After a long chat and a review of the logs with Tesla, it was determined that the car shut down early because it predicted that it could not sustain the current speed (70mph) with the amount of charge left on the battery (whatever equates to 4 rated miles). What bugs me is that they let an algorithm preemptively shut me down. I'm all for saving the battery, but not knowing what the "real" 0 is anymore really sucks.

So be careful. 0 isn't necessarily 0. It's more like 0 +/-5 (maybe 10). Which means if you dip below 10 miles of rated range, and without knowing exact state of charge, you're rolling the dice. Just thought I'd share!

I would much rather the car severely limit energy usage (and thus top speed/acceleration) and allow you to use the remaining energy than decide that it can't supply the power being requested at the moment and simply aborting.

Move that yellow energy limiter down to 30kWh if it needs to, and let me limp along for that last 1,000 feet to the charger...

 

[giants2001]

Been a while since I was able to check this thread, and there is a lot of good conversation. I could't agree more with scaesare

I would much rather the car severely limit energy usage (and thus top speed/acceleration) and allow you to use the remaining energy than decide that it can't supply the power being requested at the moment and simply aborting.

Move that yellow energy limiter down to 30kWh if it needs to, and let me limp along for that last 1,000 feet tot he charger...

Also, as Apacheguy pointed out, I was not at 0 miles. Therefore with 4 miles of rated range and about 1,000ft until my exit (which is all downhill afterwards) I was not concerned. In my mind, I wasn't even close to zero. That is until the car shut down. Obviously if I knew the car was going to shut down when it did, then I would have adjusted my driving well before to make sure that I was going to make it (with several miles of margin).
I get that Tesla is trying to get the "rated" miles calculation to be as accurate as possible, but as a user I'd rather have the "real" data displayed to me so that I can make the most appropriate decision to account for speed, slope, environmental factors, etc. Like Cottonwood said "If there is uncertainty in the calculation, Tesla should just put all of that uncertainty below 0"

One last piece of information. Tesla did pay for the towing, which is not their normal policy if a car runs out of range.