Running out of charge

[Rocky_H]

I STAYED AN EXTRA 20 MINUTES ON A SUPERCHARGER BEYOND WHEN THE CAR SAID I WAS SAFE TO PROCEED TO THE NEXT STOP. AT NO POINT DID IT TELL ME TO DECREASE MY SPEED TO REACH MY DESTINATION. NOT ONCE.

Aside from the shouting, I do have this other question. So you weren't really watching anything as you drove with this, but were just going to notice reactively if the car gave a warning message?

probably should have kept more than a 13 mile (about 5%) margin.

I had this a little off before. I said 5% as the 13 rated miles remaining, but I forgot that was the point at which your vehicle shut off before getting all the way to the Supercharger. If it had continued, it would have been 13 - 7 = 6 miles remaining. So this was actually heading toward about a 2% arrival margin as you were going. So that is the unwise part, to not pay attention to that arrival projection is showing as you go. I do recommend to everyone to try to keep that at least to 10%, rather than 2%.

I will determine my margin at Brattleboro based on 420 Wh/mi (what I get in wet weather) rather than 310 (which is what I use in dry). With a little practice you will learn to do simple calculations in your head based on your car's configuration, performance and your experience with it. E.g. if I have 120 miles to go I know I'm going to need about 36 % battery to arrive empty ( I get 3.3 miles per percent). If I've got more than 36% 120 mi out I know that I'll probably be fine at the destination. If rain is forecast I'd better allow an extra 1/3 consumption for that, update my estimated need to 36 + 12 = 48 % [...] I have posted them before here and gotten angry responses from people who say thet don't want to do all this stuff

I wouldn't be angry, but I also wouldn't try to recommend that to anyone. It is intimidating and unnecessary.

No, the solution is to charge until the energy display shows a comfortable margin and to continue to monitor that display, which will update the arrival SoC estimate continuously, as you go

This. That's it. That's all we need to recommend to new people. The car really does calculate it for you, continually updating as you drive. It is just one number you need to keep an eye on, which the car provides. And that is a very reasonable expectation to people to just watch that one number and just make sure it doesn't go too low. I think that is the key tip for new Tesla drivers. They don't have to know what the EPA watt hours per mile are for this particular model or how many extra watt hours per mile the heating is going to take. All of those values are included in realtime to the navigation's calculation of that remaining % value.

 

[ajdelange]

I wouldn't be angry, but I also wouldn't try to recommend that to anyone. It is intimidating and unnecessary.

If it intimidates you then it intimidates you and I know it intimidates others too. What I don't know is why. What I also know is that it just makes managing road trips very, very easy. If you know your car's number (that being the number of miles you normally get per percent of charge) then all you need to do is divide the distance you want to go by your number and then look at the "gas gauge" to see if there is more than that left in the "tank". What I particularly like about this is its similarity to the way we approached our ICE cars. I knew it took about half a tank to get to Brattleboro. Is there more than 1/2 tank? Yes means I can get to Brattleboro without topping up.

I know it's 176 miles from here to Brattleboro and that I am, therefore, going to need about 53% to get there. I charge the car to 70% and leave confident that I will arrive with about 17% margin. At various points, especially when approaching a charging opportunity, I take the % remaining and multiply by 3 to get an estimate of the remaining range. If that's comfortably more than the remaining distance I keep going. If it isn't I stop for charge (hasn't happened yet). That's all there is to it. No need for the fancy display though it is fun to watch. It's also fun to see how close this KISS method comes to what the display shows.

Thus I do strongly recommend that drivers learn their car's number and how to apply it.

 

[DigAdrenaline]

What are the options if you run out of charge while on a trip? Call Tesla? Do they have roadside assistance portable chargers? Does Tesla have towing to nearest charger? Call AAA?

Ok, I've ran my MS100d out of charge, semi intentionally. I wanted to make the drive from Winnipeg to Regina without charging. It's outside the range of my car, but if I slow down, I think I can make it. Actually, I still think that. But here's my experience. I had the time to wait, and I was curious, so I didn't really care if it ran out.

When I was about 35 KM outside Regina, my car showed 34 km remaining. Then it lit up like a Christmas tree with warning, and told me to pull over immediately as it was shutting down. I coasted over the the side, and called CAA. I let them know that I would need a flat bed and that it was electric (heavy). Then I put the car in tow mode and powered off the car. I dug out the tow bar, and figured out how to screw it in. The car was loaded on a flatbed and driven the remaining KMs to Regina, where I plugged it in at Peavey Mart. It took a while to get enough charge to start the computers again, but overnight it charged up and I've seen no impact on range after 5 months, and 20000KMs.

Overall, it wasn't a big deal. Part of why I was OK with running out was so that I knew what it was like and what to expect. The main take away I'd say is that it's not really a problem, but that in the same way that 100% charge should be as brief as possible, so should 0%.

Oh, and I needed to force open the charge port because the computers were off, and wouldn't power up until it was charged. The door is easy to open, but I needed to use a business card as a shoe horn to get the charge cable inserted, because the lock didn't retract either, so you couldn't just insert the connector. Any semi-rigid cardboard or plastic would work.

Hope that helps someone.

Kev.

 

[Rocky_H]

If it intimidates you then it intimidates you and I know it intimidates others too. What I don't know is why.

You really don't understand that? Most people can do math problems if they are sitting down to do that and have pen and paper and/or a calculator. You are talking about doing division problems with 2 and 3 digit numbers, with constants that they are supposed to have memorized, and coming up with very specific results like 17% and 53%. And you are suggesting that people should be able to do this: (1) in their heads (2) multi-task those math problems while paying attention to driving.

Do I need to explain further why that would feel daunting to most of the public who generally didn't like or do well in math in school? So to present to people that for them to be able to switch from a gas car to an electric car, they are going to have to learn to develop these mental math skills, is a pretty bad idea.

No need for the fancy display though it is fun to watch.

Your dismissiveness of this as just a "fancy display" makes it sound like it's a damn screen saver animation! And it comes across as terribly arrogant. That's fine that you or I can do these constant mental calculations, but it is a fact that the display is not just a pretty animation. It is doing those same calculations already. The answer is there and is continually updating as the variables shift. So it is far more realistic to be able to tell people to keep an eye on that buffer number, and adjust their driving if it is getting uncomfortably low.

 

[animorph]

We had a tricky case travelling in Texas between Superchargers. It started raining just after we left a Supercharger, but had been totally dry the segment before. We stayed an extra 10-15 minutes and got to what the nav said would be 25% to 30% charge remaining at the destination Supercharger, since we knew it would underestimate the charge needed through the rain. We monitored the charge remaining at destination (at the bottom of the turns list on the nav), and it was dropping like a rock as soon as we left, in a downpour. Aside from naturally slowing down for the rain and limited visibility, we slowed a little more and tried to follow a few trucks that weren't spraying us too badly. We tried to keep the charge at destination at about 10%, slowing or following trucks as necessary.

The same thing happens with headwinds. They can change, the car might not have enough past data to correctly estimate the effects on range. We have had no trouble getting to our destinations when monitoring the charge remaining at destination and slowing as necessary to keep it above 10%.

Our ICE experience has been that their fuel gauges were less accurate than Tesla's. Our old Mini would say 22 miles remaining when in reality it meant about 9 miles. And of course the same problems Tesla has with range are present for ICE cars, they just have more gas stations. The rated miles indication on the dash battery meter is just an estimate of the available energy in the battery. The number of real miles remaining is mostly up to the driver. It seems, from reading the forum, that most of the time the car will go to zero miles before stopping. But there have been plenty of posts where that has not been the case. I wouldn't try to cut it that close if I didn't have to.

 

[DigAdrenaline]

You really don't understand that? Most people can do math problems if they are sitting down to do that and have pen and paper and/or a calculator.

Dont forget other variables like temperature, wind, snow or rain on road, etc.

there is zero chance a human could calculate this on the fly. The variability of the energy graph over time demonstrates that.

My range is about 500km/300mi at room temperature. In a snowstorm at -40 with wind, I can’t reach half of that.

Doing this manually is taking a risk with no benefit.

 

[ajdelange]

You really don't understand that?

No.

Most people can do math problems if they are sitting down to do that and have pen and paper and/or a calculator. You are talking about doing division problems with 2 and 3 digit numbers, with constants that they are supposed to have memorized,

This is at the heart of your misunderstanding of what I am saying. I am asking people to to do division by a number close to 3. That is very easy to do as dividing by 3 is very close to the same as multiplying by 3 and shifting the decimal point by 1 place e.g. 47/3 = 16.8 ~ 3*47/10 = 14.1

and coming up with very specific results like 17% and 53%. And you are suggesting that people should be able to do this: (1) in their heads (2) multi-task those math problems while paying attention to driving.

Yes. Absolutely! We live in a nation where the average citizen cannot do this while in Japan the children participate in abacus competitions. Our citizens have been ill served by the educational system which is cranking out innumerates while at the same time ROW is emphasizing STEM. We're losing standing rapidly.

Do I need to explain further why that would feel daunting to most of the public who generally didn't like or do well in math in school?

No need. I understand. The problem is what the schools have failed to do. Despite that a fair percentage of the population has "the knack" (

). It is for them that I point out how easy it is to manage ones battery by multiplying/dividing by 3. I do not here mention that someone with the knack will realize, effortlessly, that 3*47/10 + 3*47/100 = 15.5 is even closer than to 47/3 and know how to augment or diminish that number by 1/3 or 1/4 should driving conditions suggest that this is a prudent thing to do.

What does surprise me is how few people with the knack seem to populate this forum. I bought the car because I am an engineer with "techo lust" the preponderance of buers would be similarly blessed (or cursed) to the point that I feared the knackers' market would saturate quickly and sales then stall.

So to present to people that for them to be able to switch from a gas car to an electric car, they are going to have to learn to develop these mental math skills, is a pretty bad idea.

Come now. You know full well that I never suggested that. I merely pointed out that one can manage the battery that way. In actual fact I have stated in this thread and many times elsewhere that a driver should use all the information he has available to him. This is one other bit of information that he can, and should, compare to what the fancier display shows him.

Your dismissiveness of this as just a "fancy display" makes it sound like it's a damn screen saver animation!

To you, perhaps.

And it comes across as terribly arrogant.

OK

That's fine that you or I can do these constant mental calculations, but it is a fact that the display is not just a pretty animation.

Again you know full well that this is not what I said or implied. You will find in dozens of places, even in just this thread, my exhortations to use that display. OP got into his pickle because he didn't.

It is doing those same calculations already.

Yep.

The answer is there and is continually updating as the variables shift. So it is far more realistic to be able to tell people to keep an eye on that buffer number, and adjust their driving if it is getting uncomfortably low.

And that is exactly what I have done, over and over again in this thread and dozens of others. But I do suggest the mental calculations too and for various reasons not the least of which, in my particular situation, is that I am getting long in the tooth to the point that I know the knack is starting to wane. It has been demonstrated that mental exercise of just this sort can, to some extent, slow that wane. Another reason are that as the process is exactly the same as the way one operated an ICE vehicle - you had a fuel gauge and an odometer - it may help to alleviate peoples' anxieties about having to learn new skills in order to operate a BEV. And another is that someone who takes the trouble to do this is going to have a better understanding of his car. After a time the calculations are not really needed. Once one really knows his machine a glance at the gauges is sufficient for him to assess the situation accurately enough.

 

[ajdelange]

Dont forget other variables like temperature, wind, snow or rain on road, etc.

In my brief description of how this is done I discuss how to incorporate variables like wind, snow, etc.

there is zero chance a human could calculate this on the fly.

Are you calling me inhuman? I do it all the time - on every long drive. It helps alleviate highway hypnosis. Note: I do not hold a Fields Medal. In fact I am not particularly good at math.

The variability of the energy graph over time demonstrates that.

What you are really saying is that you can't fathom how someone running mental estimates would account for that. Well someone with "the knack" wouldn't have a problem with that.

My range is about 500km/300mi at room temperature. In a snowstorm at -40 with wind, I can’t reach half of that.

If you are monitoring estimated charge at destination (using the mental method or looking at the displays) you will soon become aware that your consumption is double its normal value. Poster in No. 3 evidently had the information in front of him but didn't know how to interpret it and didn't look at the energy display. But the data was there.

Doing this manually is taking a risk with no benefit.

I have indicated what some of the benefits are. Can you tell me what the risks are?

 

[DigAdrenaline]

I have indicated what some of the benefits are. Can you tell me what the risks are?

Running out of power and being left stranded on the road with a family that hates EVs because they are stupid and unreliable and too complicated to use.

Worse if it happens during a cold winter day (which are frequent in Canada). Worse still if it happens where there is no nearby house where you can go for help. (Winnipeg to Calgary is my most common long distance route. 70% of it has no nearby people.)

 

[Vm.one]

My gas car gives 10mpg or 30mpg depending on how I drive. Drive with basic sense and it's all good.

 

[ajdelange]

Running out of power and being left stranded on the road...

I understand that this is a risk with EV's but it's no different than with an ICE vehicle. I've never run out of electricity in an EV but I have run out of gas (on the Trans Canada). What I don't understand is how doing the mental calculation adds to that risk. In fact it lowers it.

..with a family that hates EVs because they are stupid and unreliable and too complicated to use.

I assume you mean the cars but in fact they aren't unreliable and are loaded with intelligence (artificial intelligence though it may be). If you feel they are too complicated to use don't use one.

Worse if it happens during a cold winter day (which are frequent in Canada).

Much as I love it here I will soon be departing La Belle Province for exactly that reason.

Worse still if it happens where there is no nearby house where you can go for help. (Winnipeg to Calgary is my most common long distance route. 70% of it has no nearby people.)

I'm sure I would be much more on my toes were I operating out there in the dead of winter.

 

[Uncle Paul]

Just like the gauges on ICE cars, the computer in a Tesla is only a guide.

Have a friend that followed her ICE GPS on a trip to San Diego. Ended up in Tijuana Mexico. Took her hours to find her way back out.

Same with fuel gauges. They also are not precise. Usually they indicate the tank is totally full for a long time. As they get closer to empty, they drop quickly. If you are not aware or used to this inconsistency you can get caught out and run our of fuel unexpectedly.

The computer on your Tesla is not God. It gives you it's best estimate, but you are still smarter than it, so use your own judgement to determine your range.

Rules of thumb.
Always error on having less range than acual. Easier to charge a little longer than to wait for a tow truck.
Rain, Snow, Elevation, Headwinds,Speed, towing, bike racks, roof racks, soft tires, running the heater, and a heavy foot will reduce your range.
Going downiill, driving conservatively, reducing heat, running consistently, tires at specified tire pressures etc. will maximize range.

Just like in an ICE the driver is the one in charge, not the computer. Use your head.

 

[BlueOvalFan]

It HIDES the Superchargers it thinks you should skip!!!!!

This is a interesting comment. I use nav almost every day as I like to understand my arriving SoC real time anywhere I go. I have always been able to see all the super chargers around me at any time. Just wondering how old your software was when this happen. I just don’t remember this ever being a thing to worry about.

On a side note, I do have the EVTO App I use as backup to HAL 9000

 

[ohmman]

This is a interesting comment. I use nav almost every day as I like to understand my arriving SoC real time anywhere I go. I have always been able to see all the super chargers around me at any time. Just wondering how old your software was when this happen. I just don’t remember this ever being a thing to worry about.

It's phrased in a way that's a little misleading. If you are following a navigation route, and it has already calculated your Supercharger stops, it will only show those stops in your display. If you cancel the route, all Superchargers will show up. So it's not that it hides them overall, it's just that if you have a programmed route in the navigation, it only wants you to see that plan. I'm really not sure why that is, and I would agree with @Rocky_H that they really should just show them regardless. It's possible the developers thought that seeing a Supercharger might entice some people to stop when they didn't need to do so, or maybe they had some other intent with it. I believe you can still show them by hitting the charger icon on the map as well, even during navigation.

 

[BlueOvalFan]

Thanks for explaining and see the difference on how that was a problem for you. I noticed that too when on a long trip and what i typical do is allow it to plan the entire route, with SC stops. Once i know the approximate waypoint to the SC location i turn off the “SC planning route BETA” which i can then see them all. When i pull up i switch it back to “ON” to better understand how much charge i need to make it to my destination.

I suppose the only difference is I’m not canceling out of the planned route, but just switching off the “planned stops”. Different way to do the same thing.

 

[David99]

Why would you run it to even 13 miles left? No offence but that seems risky with an ev. I hate this fact about ev as you never know what that battery gauge really means.Like on a laptop.

I regularly run my car down to single digits when on road trips. In over 5 years and 240k miles I have never had the car shut down on my. Many times I was able to go a little further (not trying to do that on purpose). Especially the original batteries charge fastest when empty and much slower at higher charge levels. For fast and efficient traveling it's best to arrive rather low.

There is a problem with the battery when it shuts down with 13 miles left and no warning whatsoever before. I've seen many cases like this and Tesla replaced the battery pack.

 

[cwerdna]

Why would you run it to even 13 miles left? No offence but that seems risky with an ev. I hate this fact about ev as you never know what that battery gauge really means.Like on a laptop.

Depends on the vehicle, how its instrumentation is calibrated and any other instrumentation you might have.

Leafs for instance, do not go dead suddenly when showing numbers (in miles or km) on their guess-o-meter unless there's a defective module. Yes, the GOM sucks. Any veteran Leaf driver who know what they're doing knows to ignore the GOM.

(In the defective module case, usually the range collapse happens WAY earlier than being down to 25% battery left.)

I sometimes go to work in my 11 capacity bar Leaf about ~11 to 13 miles away with as little as 25% battery left. Keep in mind EPA range rating on a '13 Leaf is only 84 miles on a full charge and from Leaf Spy, I probably only have 81 to 83% capacity left. It's no problem. Doesn't matter if I hit the 1st warning (LBW) when the GOM starts flashing. It doesn't matter much if I hit the 2nd warning (VLBW) where the GOM turns to --- miles. By that point, I'm real close to work (with free L2 charging). And, I have Leaf Spy to see what's going on in terms of battery gids, cell voltages and max imbalance if the % state of charge display were to turn from a number to ---%.

I know I'll make it because for non-rainy days, it takes maybe 12 to 18% battery to make it there.

For rainy days, I prefer to not leave for work w/less than 30% battery, just in case. If it starts looking dicey, I just slow down and turn off the heater.

 

[Babaron]

I believe much of the problem could be avoided simply by using battery percentage on the display instead of range. I have been doing this for a long time now. It is my belief that percentage of battery left is a much more accurate figure than the estimated range left in many situations. I also try not to let it get below 10% if at all possible.

Also, as mentioned above, using the nav app in the car is invaluable as it constantly predicts how much percentage you will have at your destination. If it starts to creep down below 10%, either drive more conservatively or plan another charging stop.

Simple as that.

 

[ajdelange]

I believe much of the problem could be avoided simply by using battery percentage on the display instead of range.

From reading this forum I have to say that I have concluded that these abrupt shutdowns tend to happen to people that use the mileage display rather than the % display but I don't think having them switch over to % is going to solve the problem unless they make the switch voluntarily because, in the course of driving their cars they have learned enough about them to appreciate that the % display is more telling about battery status.

I have been doing this for a long time now. It is my belief that percentage of battery left is a much more accurate figure than the estimated range left in many situations.

I put estimated range in bold because you are absolutely right about displayed range: (% + e1)/(W + e2) ~ %/W +e2*%/W + e1/W). But rated range is just a fixed number multiplied by % and thus equally as accurate or inaccurate. This assumes that % = available kW/capacity and that the BMS doesn't decide that the battery capacity has changed.

When I first got my car (last December) I believe the energy displays gave one a choice of estimated range based on 5, 10 or 30 mile histories or rated range (fixed). Since then different firmware releases have, I believe, changed what is available. I was playing with one of them the other day and I noticed that the estimated charge at destination was jumping all over the place from moment to moment only to notice that it was based on instantaneous consumption. That is, to me, pretty useless information and I guess I can see how that might lead someone into trouble if he doesn't understand what the displays mean and I am pretty convinced at this point that many drivers do not. In any case I think part of the problem may be with shifting sands from Telsa's firmware folk.

Let's look at this gentleman's experience:

Ok, I've ran my MS100d out of charge, semi intentionally....

When I was about 35 KM outside Regina, my car showed 34 km remaining. Then it lit up like a Christmas tree with warning, and told me to pull over immediately as it was shutting down...

Were he showing % presumably his display would have indicates something like 7% remaining were it based on rated miles. Were the displayed 34 km based on an instantaneous consumption calculated during a down hill run the the remaining range estimate could have been higher. Yesterday, for example, I saw consumption of -146 Wh/mi for a short trip (all downhill) and based on that my range was infinite. But I don't think the little battery icon in front of the driver displays anything other than rated range remaining.

Oh, and I needed to force open the charge port because the computers were off, and wouldn't power up until it was charged. The door is easy to open, but I needed to use a business card as a shoe horn to get the charge cable inserted, because the lock didn't retract either

Now I wonder if this is a clue. When SoC gets low the car stops charging the 12 V battery. It is not, according to the manual for my X, supposed to do this until 0% SoC is approached but inability to get the charge port open is indicative of a discharged or failed 12 V battery. I wonder if what some of these people has seen is not discharge of the main battery but rather discharge of the 12 V battery.

...also try not to let it get below 10% if at all possible.

I think that's good advice. Remember that determining available remaining charge in a Li ion battery is tricky because terminal voltage does not change that much with charge level. The BMS has to be constantly recalibrating itself to come up with estimates as good as it does. But you can be sure that it will shut the car down if it detects dangerously low voltage even if its present charge estimate is relatively high. Clearly, below 10% you are sailing pretty close to the wind.

Also, as mentioned above, using the nav app in the car is invaluable as it constantly predicts how much percentage you will have at your destination. If it starts to creep down below 10%, either drive more conservatively or plan another charging stop.

I believe the cause of the "problem" is that people don't use the energy displays. If you have "the knack" you don't need them (except to back up your estimates) but if you don't you really do.

 

[David99]

Showing percentage vs range in miles is not the issue.
Percentage is simply 'capacity' / 100.
Range is 'capacity' / 300. (using a range of 300 rated miles)

Range in miles is a finer granularity. It is the exact same, only showing range in miles is a more accurate value as it as 300 steps vs 100 steps.

The issue is that the car shut down showing 16 miles remaining. That should never happen and indicates a issue with the battery for sure. Just recently an owner in Texas had this issue. Tesla claimed all is normal and later replaced the battery under warranty.