darth_vad3r
Well-Known Sith
No, it’s not SoC% times consumption factor. It’s energy in kWh times a factor.
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Percentage or Miles/Kilometers : which do you use and why?
- Thread starter JulienW
- Start date
No, it’s not SoC% times consumption factor. It’s energy in kWh times a factor.
No--still doesn't care how that relates to the current state of charge percent value. It's how many kilowatt hours of energy it presently thinks are in there, multiplied by that EPA consumption constant of how many rated miles it gets per kilowatt hour.
darth_vad3r
Well-Known Sith
That's not how it works either. Just take out the SOC% part.
Here's how it roughly works, as far as I understand, from reading lots of posts from knowledgeable people here on the forums ...
- A bunch of factors are taken into account to come up with a best *estimate* at what the energy content in the battery is now, call that E (kWh). The BMS and other computers on the car are factoring in tons of inputs ... voltages of bricks/modules, battery temperature, historical patterns of charge/drain?, etc, etc, etc.
e.g. E = 25kWh - Using a similarily scientific "bunch of factors", a maximum capacity M (kWh) is determined.
e.g. M = 50kWh. (this is different than say the 'factory' initial maximum capacity Mf = 52.5 kWh) - Distance D is displayed by multiplying energy E by a factor F (internal constant, mapping miles to kWh, e.g. 1 / X Wh/mi).
e.g. D = E * F = 25 kWh * (1/219 Wh/mi) = 114 mi - SoC% is displayed by showing E / M rounded to nearest %.
e.g. 25/50 = 50%
When the car was new, if the pack was 52.5kWh, 50% would have corresponded to 26.25kWh, and 120mi.
Well said!
Many of the comments here arguing for displaying miles are from people who have a more sophisticated understanding of the car, the battery, and the probable method the car uses to calculate the SOC, than does the average driver. I would say that for the average Joe, and especially for the people who don't live in temperate climates, the display in miles is just plain misleading so often that those folks get unnecessarily worried about the condition of the car and what might be "wrong." Tesla effectively misleads them into thinking the battery gauge shows the range in distance when actually, as others have said, it is using distance as only as a proxy for energy. It is accurate as a literal distance indicator only under very narrow conditions that many of us rarely achieve. So as you say, it is confusing to newbies when their real-world experience does not match what they see on their screen. (For me, it might work for a few nice days in spring or fall when my energy use per mile is close to the EPA rating, but otherwise it will be off.)
The enthusiasts, the people who have made long scientific explanations here, can make sense of the distance indication, but unfortunately most people can't. Or they don't want to try to unravel the conflicting theories of how the car calculates the displayed range (see the various guesses at the algorithm in the posts above).
A lot of the comments seem to be about tracking degradation of the battery over time. Personally, I have not (yet) tried to track my battery degradation. Maybe I am in the minority, or naive, or foolish, etc. I do not try to use the SOC indicator for that. Maybe someday I will. For now, I am just driving the car.
Wooloomooloo
Member
It doesn't look that way. I use percentage and usually suggest others do the same. The distance metric is relative, I think creates anxiety as you see it drop 2 miles before you've driven half a mile and then it evens out a bit etc. It's a bit like having your laptop display battery time remaining rather than percentage, it would just fluctuate so much dependent upon exactly what you're doing at that point.
As you get to know your car, you can do the math more reliably with the percentage than the rated range. My car goes from 2.5 miles per % to 4 miles per % between winter and summer at about 55mph so 50% will get me 150 miles - 200 miles. If the rated range saying 170 miles, that just obscures things for me.
bwilson4web
hit the spot
I drive by "reserve miles", the difference between the navigation listed miles to the next charger or destination and battery miles. A simple subtraction lets me see how much reserve I have early enough to adjust. Typically, I want 30-40 miles reserve depending on conditions:
- reserve miles decreasing - slow down and look for short cuts
- reserve miles constant - no problem
- reserve miles increasing - have fun
- 40 miles - no problem
- 30 miles - stay alert
- 20 miles - Uh Oh! Think about other charging sources like L2 chargers
- 10 miles - Ok, time to drive Prius style and find nearest L2/NEMA 14-50
That is a pretty good point. I guess I would modify it a little bit. I don't think people have to understand the mathematical or scientific details of exactly why, but it is certainly down to the difference in time of ownership--inexperience versus experience. If you've lived with the car for a while and are comfortable and familiar with how the rated miles number just always runs a little optimistic, then it's not worrisome to use the number but "fudge factor" it downward some.
But I never really saw gas mileage mpg numbers as gospel truth either, so it always seemed normal to me to be relaxed about it anyway.
TT97
Active Member
What is Prius style in Alabama? In L.A., Prius drivers are second only to BMW owners in their aggressiveness even though my Ninja blender has a more powerful engine.
https://jalopnik.com/science-confirms-that-bmw-and-prius-drivers-are-the-wor-1120783177
clostridium
Member
I fully understood what he wrote. Yes if you are getting exactly the same efficiency you would make it but I don't understand how this is an argument for using miles instead of percentage. I also don't understand how you can bet that you will get the same efficiency unless this is a road you know very well and you know there won't be any major variations in weather or other factors.
The best way to get a quick estimate for this specific question is to go into the power app and see what it is estimating for your range rather than doing mental gymnastics for when rated miles are better or worse than real miles.
Miles vs. percentage is ultimately a preference thing. I find it strange to discuss some miles as being different than others. It makes more sense to me to use percentage and the mental math makes more sense to me. I'm certain that everyone on this thread is smart enough to run the estimates either way so it's about what makes the most sense and is easiest. Really what would be best is if the car would report estimates based on your performance like on the power app.
Range miles. Having gotten to my 20% on occasion I know the amber battery will display so that's good enough info for me to know I need to charge soon, and in the meantime will lose my cabin overheat protection and sentry mode.
And yes I'm aware that there is battery degradation over time and there's also rebalancing that can be done. I guess with my driving trips, local for the most part in my Model 3, I don't ever cut things that close even though I don't charge every night.
After driving your car for a while don't most people know about what mileage range their 20% is any way? I prefer to enjoy driving my car and not fret over what kind of efficiency I'm getting or counting every statistic. I understand it would probably be different if I was doing more long-range driving and having to factor in other things, but I don't need to for my routes and know I can rely on the trip meter for the most part and just build in a little cushion if I'm at all nervous about conditions or drive slower or turn off the A/C, etc. Driving in the bay area however there's always somewhere within easy reach to plug into a L2 charger if you really need to.
And yes I'm aware that there is battery degradation over time and there's also rebalancing that can be done. I guess with my driving trips, local for the most part in my Model 3, I don't ever cut things that close even though I don't charge every night.
After driving your car for a while don't most people know about what mileage range their 20% is any way? I prefer to enjoy driving my car and not fret over what kind of efficiency I'm getting or counting every statistic. I understand it would probably be different if I was doing more long-range driving and having to factor in other things, but I don't need to for my routes and know I can rely on the trip meter for the most part and just build in a little cushion if I'm at all nervous about conditions or drive slower or turn off the A/C, etc. Driving in the bay area however there's always somewhere within easy reach to plug into a L2 charger if you really need to.
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To me the single most important feature Tesla has developed for their cars is the trip planner. It calculates energy usage based on real world data they gathered and tells you how much battery you will use and what your arrival percentage will be. It has gotten so good that I can rely on it down to 1%.
The key is that neither percentage nor miles are helpful. Both are not considering the route you will be driving thus they are both equally useless. Only the trip planner does that. Honestly, when driving to a new place I have never been, I don't even look at the distance in term of how much charge I need. I use the trip planner and go by that. I don't look at miles nor percentage.
The key is that neither percentage nor miles are helpful. Both are not considering the route you will be driving thus they are both equally useless. Only the trip planner does that. Honestly, when driving to a new place I have never been, I don't even look at the distance in term of how much charge I need. I use the trip planner and go by that. I don't look at miles nor percentage.
follow.johnny
FSD Beta Tester
Clearly percentage is the obvious answer. Why you ask? Everyone “should” be using the Tesla navigation and it shows what percentage you will be at when you arrive at your destination and updates in “real-time” base off your driving speed and conditions.
Then again this is my opinion
Then again this is my opinion
bwilson4web
hit the spot
That 2013 article is a little dated. Back then, hypermiling advocates were teaching poor driving techniques, especially the "pulse and glide" style.
Rather, I used efficient driving based on vehicle tuning, performance metrics along with large, slow vehicles as camouflage, and efficient trip planning. As for a driving stunt, here is one tank of gas I did over three weeks commuting to work in July 2013:
As for whether one uses percentage or miles, whatever cranks your tractor works for me too. I have a lot of miles experience with my BMW i3-REx and former Prius experience. When looking at a map for an optimized route, miles work best for me.
Bob Wilson
Here's the fun with this though...who's to say that the trip planner accounts for battery degradation? What is the trip planner using for a reference since it is seems likely that it will still show 100% for "full charge" even after degradation. I would suspect that it is still going to assume a set kWh per percent based on original battery capacity.
This doesn't say anything though. What is your battery degradation, how did you figure out your battery degradation? Also, if your degradation isn't a lot, it would be hard to actually prove that the trip planner is using current available capacity. It can be done though.
Show your work.
You figure out degradation by taking new Ideal miles vs current Ideal miles. Yes, the correct way is to go from 100% to 0 a couple of times, but that's hard on the battery. Tesla appears to mess with the Ideal miles algorithm less than the Rated miles algorithm.This doesn't say anything though. What is your battery degradation, how did you figure out your battery degradation? Also, if your degradation isn't a lot, it would be hard to actually prove that the trip planner is using current available capacity. It can be done though.
Show your work.
Based on the number of trips I take and the places I take them, if the estimated difference was out by a lot I wouldn't make the destination.
Best I can tell, it's 7% currently and has been rather consistent for the past several months.
Tried miles for a few day and now switched back to percentage. Each seems to have their merits and drawbacks. Can't remember but I think it was milage by default. Seems a little odd that Tesla doesn't switch Navigation to match Milage if selected.
darth_vad3r
Well-Known Sith
What part of navigation? IIRC the bottom shows target % remaining, is that what you mean, instead of “miles” remaining? I think that’s just cherry picking the data shown on the energy “trip” tab so that if you just want to know that you can see the map still without switching to energy trip screen.
I don’t mind forgoing the map screen and leaving the energy trip tab up so I can see the trip chart to see if I’m doing better or worse than expected. For me the units on that chart don’t really matter, but if you want to see both miles and percent that’s one way to see both.
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