Were these secondary roads stop and go? Did the higher temperatures mean you were also running A/C? The EPA estimate for city indicates higher consumption than the EPA estimate for highway, and that is because you're wasting energy stopping and starting. Running the A/C can compound this, because it draws energy over time vs energy over miles, so at a lower speed, it will draw more energy per mile.
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Range Failure
- Thread starter gnuarm
- Start date
Here's a simple estimator:
At any point on the journey see how far it is to your destination. For example purposes lets say it is 60 miles. Divide this by one one hundreth of your EPA rated miles e.g. for an X100D that'd be 295/100 = 2.95. Three is close enough for government work so we'd take 60 (mi)/3(mi per percent) and get 20% as an estimate of the charge we'd use in doing those remaining 60 miles if the EPA conditions applied. Now look at the current SoC. Suppose for the example that it is 35%. Subtract the estimated 60 mile requirement (20%) from that to find 35 - 20 = 15% as your estimated SoC at the destination. Are you comfortable with that? If so, sail on. If you are not, head for a nearby charger. You should have determined where that is before you left.
This is a "crappy" estimator because it assumes that a particular set or driving conditions pertain where they very probably don't. You can improve the quality of the estimate by applying some English based upon actual driving conditions and determined by comparing your displayed (actual) consumption to the consumption that corresponds to the EPA rated range. For the X100D EPA range with a 102 kW battery that's 102000/295 = 345.7 Wh/mi. If your display shows that you have used 400 Wh/mi over the last 30 miles you quickly see that's about 400/350 = 8/7 times the EPA value and that your usage, if the conditions over the remaining 60 miles are the same as they were over the last 30, be 20*8/7 or approximately 22.8% rather than 20% and your margin at trip end will consequently be 2.8% less than 15% or 12.2%. Still comfortable? Note that the car applies this English for you but as you have trouble understanding what it is doing perhaps you'd best just stick with the divide by 3 method.
It's clear that neither of you two have been exposed to estimation theory but it is nevertheless important that you grasp one essential concept: an estimate is a guess. Some estimators are more "robust" than others (offer better predictions than others over a wider set of conditions) but they are still estimators.
At any point on the journey see how far it is to your destination. For example purposes lets say it is 60 miles. Divide this by one one hundreth of your EPA rated miles e.g. for an X100D that'd be 295/100 = 2.95. Three is close enough for government work so we'd take 60 (mi)/3(mi per percent) and get 20% as an estimate of the charge we'd use in doing those remaining 60 miles if the EPA conditions applied. Now look at the current SoC. Suppose for the example that it is 35%. Subtract the estimated 60 mile requirement (20%) from that to find 35 - 20 = 15% as your estimated SoC at the destination. Are you comfortable with that? If so, sail on. If you are not, head for a nearby charger. You should have determined where that is before you left.
This is a "crappy" estimator because it assumes that a particular set or driving conditions pertain where they very probably don't. You can improve the quality of the estimate by applying some English based upon actual driving conditions and determined by comparing your displayed (actual) consumption to the consumption that corresponds to the EPA rated range. For the X100D EPA range with a 102 kW battery that's 102000/295 = 345.7 Wh/mi. If your display shows that you have used 400 Wh/mi over the last 30 miles you quickly see that's about 400/350 = 8/7 times the EPA value and that your usage, if the conditions over the remaining 60 miles are the same as they were over the last 30, be 20*8/7 or approximately 22.8% rather than 20% and your margin at trip end will consequently be 2.8% less than 15% or 12.2%. Still comfortable? Note that the car applies this English for you but as you have trouble understanding what it is doing perhaps you'd best just stick with the divide by 3 method.
It's clear that neither of you two have been exposed to estimation theory but it is nevertheless important that you grasp one essential concept: an estimate is a guess. Some estimators are more "robust" than others (offer better predictions than others over a wider set of conditions) but they are still estimators.
That is the most outlandish perception of "simple" I have ever seen.
Miles to travel divided by 3 is what I do when I'm thinking about heading out (or home) without a full charge with no chargers available between my start point and destination (more often than you might guess). I don't know how it could get much simpler than that, but I complicate it beyond that by also calculating miles divided by 2 and guessing how far in between those I'll actually fall (maybe close to the /3 when it's 50-60 out, probably close to the /2 when it's below 32 out, and somewhere in between outside of those ranges) and deciding whether or not I feel safe with the remaining buffer after that guess.
I still would not want to arrive at destination with only 12% remaining. Things happen and the estimate could be based on incorrect/bad data or assumptions, like me not driving faster to keep up with the flow of traffic. I try to arrive at any Supercharger with no less than 25% remaining. And feel better at 30%. Just my personal comfort level.
Moderator note: Moved two posts to Snippiness. Insulting other TMC members is against forum rules.
Bruce.
Bruce.
juliusa
Active Member
Yes - and that is what I was referring to. Had he used Trip Planner, he would have charged more.
BTW, I am not convinced it showed 5% remaining upon arrival at destination when he left the charger, then along the way showed 12% remaining, and then dropped to below 0%. There are a lot of missing details for us to better understand what happened - what model, size battery, which superchargers and L2 chargers involved, distances, about when on the route the 12% remaining reading occurred, about when it dropped below 0% remaining, warning messages received (drive below xx mph to reach your destination; charging needed to reach your destination) to name a few.
I'm skeptical, but certainly believe this could have happened. If it did happen, it is a very unusual occurrence and not something to worry about. "Most" people would learn from an experience like this that they should use Trip Planner if they want Tesla to tell them when they have enough charge to leave for their destination or next charger, and leaving with an estimated 5% available upon arrival is a risk.
I get that, but it means you don't get much range which is no small part what you pay for in the car. On longer trips I want to be able to drive at least 200 miles so I can make it a meal stop while charging. Spending 20 minutes at a charger five times on a 500 mile trip is a pain in my opinion. To each their own.
What trip planner??? This is one of the really confusing things when different people tell me different things... or even the same people tell me different things. One thread I was talking about how the car wasn't very good for planning while I was charging for a trip I needed to start early in the morning. I had a pretty good idea of my starting charge level and was trying to use abetterrouteplanner.cm. I got jumped hard by a bunch of people telling me the only real way to plan a trip was to use the car in spite of the fact that it couldn't be done with the actual value of starting charge.
Now you seem to be telling me to use some planner other than the car navigator. My head spins with the conflicting advice.
The real problem with ABRP is that it is only as good as the mileage data you give it and there is no way to come up with a number. The default number in the tool seems to be ultra conservative compared to what I actually obtain. In fact, I still need to pull the numbers from the car, but I think the calculated numbers in the trip page in the car are just wrong. I tried doing a calculation in mid trip and using the numbers they showed there was something like 7% of the battery used but not accounted for!
All I can do is provide the facts. It sounds like you think I am lying or very stupid as I can't thing of any other way the numbers I give you would be that wrong.
I have no idea what you would do with all that info. But I have already giving a lot of it. I did provide distances and exactly when the range started to drop and I talked about when I ended up charging at an L2 charger. There were no warning messages other than telling me to drive to a different charger (back tracking at one point, but I don't think I could have reached that one either since I had gone so far). The car is a P100D.
Just the opposite. A very unusual occurrence that can happen at any time is the WORST thing since you are not likely to be prepared for it.
I don't know what trip planner you are talking about. You also continue to go on about the 5% number which was not a factor since I would have had nearly 50% when I passed the two Superchargers along my route.
So if you have nothing useful to add to the thread, please stop posting misinformation. Ok? Thanks.
A little bit, but nothing to impact the range. There was a stop sign every few miles and by that I mean four to 10 miles.
I think I was running the AC, but I can't believe it would have that serious an impact as soon as I left the highway vs being on while on the highway. One thing that would make a difference in this situation is that while the AC would be using about the same Wh, the car is going slower on the secondary roads and so the Wh/mi would be higher.
Still, it is hard to imagine that it would be able to eat up such a large percentage of the energy on this final 60 miles of the trip.
Today I make the reverse trip. I started with some 8x% charge and the navigator took me on the same route but to charge at the first charger along the highway. The estimated remaining charge did drop as I drove on the secondary roads and I drove at the speed limit or for part of the way below the speed limit because the car didn't know what it was and wouldn't let me auto pilot above 35. lol That was a short stretch, about 6 miles. By the time I reached the highway I had lost about 3% of the arrival charge estimate. While on the highway that number went up.
On the second leg after charging for almost an hour, the arrival estimate was 12% (again two chargers would be on the way) and rose to 18% by the time I took a different turn off the highway than the one the navigator suggested. Then the estimate jumped up to 22% which is what I arrived here with. I wonder what the navigator is optimizing to take a longer route that uses more of the battery. I don't think it is any faster since I got home at the estimate I had been staring at for the last two hours. Google says they take the same time.
So the trip today was as usual except for the small loss of range on the initial secondary roads while the final secondary road section (about 29 miles) cost me nothing in range. Go figure!
There was some funny business with the trip calculations, but I want to write them down rather than recalling them. Tomorrow.
On the second leg after charging for almost an hour, the arrival estimate was 12% (again two chargers would be on the way) and rose to 18% by the time I took a different turn off the highway than the one the navigator suggested. Then the estimate jumped up to 22% which is what I arrived here with. I wonder what the navigator is optimizing to take a longer route that uses more of the battery. I don't think it is any faster since I got home at the estimate I had been staring at for the last two hours. Google says they take the same time.
So the trip today was as usual except for the small loss of range on the initial secondary roads while the final secondary road section (about 29 miles) cost me nothing in range. Go figure!
There was some funny business with the trip calculations, but I want to write them down rather than recalling them. Tomorrow.
juliusa
Active Member
Have you read your manual?
Nope.
Trip Planner
Trip Planner helps you take longer road trips
with confidence. If reaching your destination
requires charging, Trip Planner routes you
through the appropriate Supercharger
locations. Trip Planner selects a route and
provides charging times to minimize the
amount of time you spend driving and
charging. To enable Trip Planner, touch the
map's settings icon (see Overview on page
122), then touch Trip Planner.
When Trip Planner is enabled and charging is
required to reach your destination, the turnby-
turn direction list includes Supercharger
stops and a recommended charging time at
each Supercharger, and an estimate of how
much energy will be available when you arrive
at the Supercharger.
I believe you are providing the facts as you believe them to be true. Does not mean that is what happened.
That is why more details help - as people provide more details it helps them remember more, and often shows inconsistencies in their memory. People are terrible witnesses.
What charger did you start at? What was your SOC when you left, what was your destination, and what was the estimated % remaining upon arrival? What was your SOC% and distance to your destination when it showed 12% remaining upon arrival? What was your SOC% and distance to your destination when it showed less than 0% upon arrival?
Not sure why you did not get warning messages about slowing down to reach your destination, or that charging was required to reach your destination. I get those annoying messages all the time when I drive, because I often cut it close.
juliusa
Active Member
I think the disconnect here could be what you see as "funny business" is simply "business as usual" for most. With so many factors affecting the actual mileage a car gets on a route (EV or ICE), there is a limit as to how accurate a trip estimate will be.
I would agree that stopping every 4 to 10 miles shouldn't be too significant. However, you said you were driving slower during the hottest portion of your trip, so I should think the A/C might be drawing more Wh/time and that might be compounded by the lower speeds. My only significant experience with A/C effecting range was in a Turo-rented P90D when I got stuck in some very slow moving city traffic while using A/C. It's been a couple years, but IIRC, my Wh/mi went up to the 600s on the 30 mile consumption chart, which is pretty significant vs the typical 300s. Obviously, as you were moving, it wouldn't have been as significant, but if you went from driving 70 to driving 35, the Wh/mi consumed by the A/C would double without more Wh/time being used due to higher temperatures. Those higher temperatures paired with lower speeds could also have lead to higher battery temperatures (less airflow from vehicle movement) and even more A/C demand due to that. I know I've heard that the battery is happiest at something like 85 degrees F, but I'm guessing that's battery temp, not ambient temp, as I've heard the A/C compressor running to cool the battery in my X100D when I don't even have A/C on and temperatures are much lower than that. In addition to all of that, there certainly could have been other factors playing into the event, too.
Might be age also. In am over 60 so my prostate, not the battery, is the range limiter for me
. 2-2/12 hours is my max comfort level on the road.
I don't think the AC can be that large an input to the range calculation. If it were, the car would consider that.
The bottom line is the range estimate has to be accurate or you can be stranded. Even when Superchargers are 25 miles apart on the highway, they won't be so common on many routes. This path had about 50 miles with nothing like a proper town or even a 10 buildings in one spot, so no Superchargers or even destination chargers here. lol
I was very, very happy to see the town of Conway had installed a small number of units for EV owners. In fact, I need to write them and let them know the big help they were on my trip.
Might be age also. In am over 60 so my prostate, not the battery, is the range limiter for me
Yeah, it's not unusual for me to need a pee break before stopping for a meal. But still, I think a goal of driving for four hours between charges is not unrealistic and that will require more chargers so you can better match the car's range to the charger locations.
That's just the bloody car navigator that I'm already using!!!
Ok, still sounds like you are saying I'm either lying or stupid.
I told you that most of this is already posted. You just have to read.
No warning to reduce speed because my speed was already reduced. I've stated that several times. It is pretty clear that you don't really read my posts. You just react to something in them you don't seem to like.
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