darth_vad3r
Well-Known Sith
That is a horrible assumption. “%” is the user facing number. Internally the car is using kWh, and Wh/mi, and trip distance, speed, and elevation changes to calculate trip estimate and chart.
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Percentage or Miles/Kilometers : which do you use and why?
- Thread starter JulienW
- Start date
That is a horrible assumption. “%” is the user facing number. Internally the car is using kWh, and Wh/mi, and trip distance, speed, and elevation changes to calculate trip estimate and chart.
darth_vad3r
Well-Known Sith
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
But if you are using the energy trip tab with the chart that updates both the end % and the current % in “real-time” it makes it unnecessary to display the current percent a 2nd time on left side display
No...the difference between your current SOC and the destination SOC is based on distance/speed/elevation, but that individual shown values are based on what it thinks full is. If 100% charge is really 90% of original capacity because of degradation, then what makes you think that the % value in the trip estimate is not using original capacity? People have already said that with in the Model S, with degradation, it still shows 100%(or 99%) at full charge even though that full charge isn't original capacity any more.
darth_vad3r
Well-Known Sith
% is a user facing number only. Internal calculations use energy and distance, etc.
% is shown to you to make you understand “easily” where you are at with a dimensionless number.
The car says “I think have X kWh now, and this trip will take Y kWh, so I’m going to end with Z kWh”. Then it displays that to you as a %. No engineer or developer would perform the math with “%”, trust me.
SSonnentag
埃隆•馬斯克
I know how many percentage points it takes to get from point A to point B. A guess as to how much range is left is meaningless to me unless your speed, terrain and environment are constant.
For instance, I know it takes me 50% to get from home to work, but 75% to get from work to home. It's the same number of miles, so knowing my range in miles is meaningless. Prevailing winds and elevation change make all the difference.
For instance, I know it takes me 50% to get from home to work, but 75% to get from work to home. It's the same number of miles, so knowing my range in miles is meaningless. Prevailing winds and elevation change make all the difference.
darth_vad3r
Well-Known Sith
Except that if you learn those two data points in “miles” it should stay consistent over the lifetime of your car, even after degradation. You might find it takes “51%” after some degradation and “77%”.
If you used miles instead it would stay consistent.
EDIT: Really they should show kWh. You should learn that it takes you X kWh to get to work and Y kWh to get home typically.
The best gauge we have (currently) to judge remaining kWh in the pack is miles, not %, because % changes over time with degradation. Miles also has more granularity, and km even more.
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SSonnentag
埃隆•馬斯克
I don't see how as both miles and percentage are based upon the same voltage readings.
darth_vad3r
Well-Known Sith
If you charge a degraded battery to 100%, it says “100%”, but shows less miles.
Miles is a reflection of kWh estimated in your pack.
% is a reflection of percent of your current “100” level which is unknown to you directly.
SSonnentag
埃隆•馬斯克
I suppose that could affect things a bit, although I can't get my car to charge above 99%.
This is getting a little OT, but there is plenty of data and proof that the car keeps track of the battery degradation. I have been monitoring the BMS data on the CAN bus for years on my car and so have many other people. The data is right there. The BMS tells you the battery capacity in kWh and range (miles or km). Everything connected to that (trip planner, range display, percentage) is properly adjusted to that.
Absolutely I agree that the BMS keeps track, but how do you explain a degraded battery charging till it stops and still showing 100% on the charging screen? There have been people who have said that happens on the S. Yes I am referencing an S and not a 3 but a lot of people also say that "it should be the same". I don't necessarily believe that...but I haven't seen anyone with a 3 that has actual battery degradation come out with what their car shows and how it behaves.
Because it's 100% of the energy that can be stored in the battery at the current time. The Ideal or Rated range will be lower to reflect any degradation that occurs. The car does not keep track of the initial amount of energy being capable of being stored.
So if the battery could be charged to 77 kWh when new and is now 66 kWh, it's now 100% of 66 kWh.
AlanSubie4Life
Efficiency Obsessed Member
Here's a definitive picture of how things behave on Model 3 in the presence of "degradation" (I say degradation in quotes because probably in this case there was some other issue but the effect is similar; usable capacity is limited), and why setting % display could be misleading. Though the picture does not show it in text as a %, it does show it in the picture of the battery - this battery in an LR is charged to 90%. It has ~142 miles of range.
This battery was replaced.
Lost 50% range on my battery
If this user had completely relied on percentage and attempted to make a 2-hour drive to Montreal in the middle of winter, without using the trip planner...it would have been bad. Obviously an extreme, improbable case. But that's the argument that people who prefer miles over % have been making. In practice, if you use the trip planner, it won't matter, since the car knows about how much energy is available and will attempt to ensure you do not run out.
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darth_vad3r
Well-Known Sith
Occam's razor... If assuming anything, assume 3 works same as S unless proven otherwise. Do NOT assume it works differently until proven it works the same.
... also, see above post
If you displayed range in mi or km, you would notice varying numbers when charging repeatedly to a fixed %. This clearly indicates that there *is* a discrepancy between how distance and "%" are displayed to the user. The simplest explanation is that % is a percent of current total max capacity, and the distance is the current energy stored translated into distance using an internal constant efficiency/consumption number in Wh/mi or Wh/km.
I defy you to come up with a simpler explanation
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Kleenerth3
Member
You can make an argument fo miles...but it's not relative miles to your driving habits, weather, terrain, etc so it is only a guideline at best. So you can't plan a trip and use the miles shown as an absolute guid for a trip. Using Navigation is a much better method to determine range capacity.Miles. Period. You plan a trip, miles. You want to figure degradation? Miles. What percentage of 325 have you? Miles. The car figures% and tells us when and where to charge. We don't need to know%, our cars fill us in.
Plan a trip on %? Keep it simple.
Saw where someone used about the same reasoning fo percentage. Stating that in their SR+ they got about 2 miles per percent and could use this to determine the range or trip.
Did a road trip (All-Sav) this weekend and used Miles. Going to switch back to Percentage this week and see. Seems that after you use one for a few days you become more familiar and comfortable with it.
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Kleenerth3
Member
I couldn't agree more. Point taken until you factor in the regular driving habits of the regular driver making a regular routine. I forget a lot of people are making many, short trips or the regular drive to work and not setting the navigation to allow your car to figure in the stop.
Still IMO, easier to figure miles and use % from there. Thanks for the enlightening.
Considering the tech in this car that concern can be resolved easily with some programming and giving user control. Allow drivers to set the parameters by selecting a revolving time or miles for use in the miles remaining calculation. This is how ICE calculations work so why not in EV? In ICE cars the computer uses the mpg from the most recent consumption to calculate the miles remaining to "empty". Given the advanced OS of the Tesla we could simply choose for example; Use the last 5 minutes consumption efficiency average to determine miles remaining. As conditions change the calculation values change constantly.
This is really rather simple and gives the most relevant data to the driver so I feel it is what we should all be pushing for instead or debating which sub-par option is best.
You could, but the next five minutes may be nothing like the last five minutes. I don't see how that would be an improvement over the choices already there. And with the trip graph, it's really just not necessary.
Now years ago, before the trip graph, what I did was use a combination of rated range and the energy graph. If the energy graph showed more than the rated range, I knew I was golden, but I haven't used this technique since the energy graph was implemented.
It isn't about taking periodic blocks of X# miles (minutes) of consumption, but a constant calculation that updates say every 10 seconds using the average of the last X# miles (minutes) selected. If I am driving my regular route this would be very reliable 95% of the time. If all of the sudden the highway is shut down to a crawl for a roll over I would expect that calculation to change accordingly the longer I am in that situation. It is the most relevant data for a driver trying to achieve MILES (not percentage of charge) of movement to get to a destination. Basically, it is just displaying the same data used in Nav on the miles remaining display but in a different presentation if no destination is entered.
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