Can someone explain why the instant projected range isn't the same across the different scales on the energy graphs? It's pretty clear that the average energy use over the 5, 15, and 30 mile scales would be different, but I'm having a hard time understanding what would make the instant projected range be different...
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Why is the instant projected range different on the 5/15/30 energy graphs?
- Thread starter KiddFunkadelic
- Start date
It looks like "instant" is relative. If you look at the last 5 miles of data in any of the three scales, you can see the data is actually different. I suspect the 30 mile scale is averaging the last (say) 6 data samples, the 15 mile scale is averaging the last 3 data samples and 5 mile scale is providing the last data sample. We should probably interpret "instant" as the projected range assuming the last *displayed* data point.
That's a good and valid question. Instant should be the same in theory. Here is my theory. For instant consumption it seems the graph uses the 3 most recent samples, makes an average and shows it. At the different settings (5/15/30 miles) the distance between these samples is different. Just a wild guess, though
Think of it this way.
In the last five minutes, I was going downhill and had lot of regen, average range is therefore spectacular.
But for the 10 minutes before that, I was on a flat road, where the 5 min graph was good. But the flat combined with downhill gave an above average range.
But for the 15 minutes before that, I was going uphill with terrible 5 and minute range.
So at the end of the route it averages out to a slightly less than normal range at 30, an above average on the 15 and totally awesome on the 5
In the last five minutes, I was going downhill and had lot of regen, average range is therefore spectacular.
But for the 10 minutes before that, I was on a flat road, where the 5 min graph was good. But the flat combined with downhill gave an above average range.
But for the 15 minutes before that, I was going uphill with terrible 5 and minute range.
So at the end of the route it averages out to a slightly less than normal range at 30, an above average on the 15 and totally awesome on the 5
SomeJoe7777
Marginally-Known Member
The projected range is an estimate based on the average energy usage on that particular graph and the amount of energy left in the battery.
If you have 40 kWh of energy left in the battery, and your average energy use on the graph is 400 Wh/mi, then your projected range on that graph is 100 miles. (40k/400)
SInce the average energy use on each graph is different because it's based on the energy use while driving the last 5/15/30 miles, then the projected range will also be different.
It is conceivable based on your driving that your 5/15/30 mile graphs might have average energy usage of 400, 300, and 250 Wh/mile respectively. If you have 40 kWh of energy left in the battery, then the projected range on each of those graphs will be 100, 133, and 160 miles, respectively.
These graphs are the only thing in a Tesla that can give you a projected range that is based on your driving. The battery meter itself gives you "rated miles" which is based on the amount of energy left in the battery and a constant fixed efficiency that the EPA determined (about 235 Wh/mi).
If you have 40 kWh of energy left in the battery, and your average energy use on the graph is 400 Wh/mi, then your projected range on that graph is 100 miles. (40k/400)
SInce the average energy use on each graph is different because it's based on the energy use while driving the last 5/15/30 miles, then the projected range will also be different.
It is conceivable based on your driving that your 5/15/30 mile graphs might have average energy usage of 400, 300, and 250 Wh/mile respectively. If you have 40 kWh of energy left in the battery, then the projected range on each of those graphs will be 100, 133, and 160 miles, respectively.
These graphs are the only thing in a Tesla that can give you a projected range that is based on your driving. The battery meter itself gives you "rated miles" which is based on the amount of energy left in the battery and a constant fixed efficiency that the EPA determined (about 235 Wh/mi).
The last two replies missed my question - it's not about the average energy use or project range, it's the instant / current energy use and how the scale would make any difference / be different for the 5/15/30 mile views...
RedModel3
Member
TT97
Active Member
This is purely my guess:
Say each view has the same X data points (hypothetically, let's say it is 500 data points). On the 5-mile chart, each point is equal to 1/100 of a mile (53 feet). On the 30-mile chart, each point would be 3/50 of a mile (317 feet). The car measures the efficiency for each 53 or 317 foot segment (which would also explain why the 30-mile doesn't have the same extreme peaks and valleys as the 5-miles). The "instant" range is the range based on the last calculated data point, but as the length of the data point differs for each chart, the instant range also differs.
Say each view has the same X data points (hypothetically, let's say it is 500 data points). On the 5-mile chart, each point is equal to 1/100 of a mile (53 feet). On the 30-mile chart, each point would be 3/50 of a mile (317 feet). The car measures the efficiency for each 53 or 317 foot segment (which would also explain why the 30-mile doesn't have the same extreme peaks and valleys as the 5-miles). The "instant" range is the range based on the last calculated data point, but as the length of the data point differs for each chart, the instant range also differs.
Brando
Active Member
That's an informative video, but still does not answer the OP's (and my) question: Why do the "instant" values change based on the 5/15/30 mile averaging settings?
AlanSubie4Life
Efficiency Obsessed Member
I think the first response here from two years ago gives a reasonable guess for why this works this way. Why is the instant projected range different on the 5/15/30 energy graphs?
If you look at the actual position of the last point, and run the calculation using the known charging constant for the vehicle, (remaining rated range * charge constant / instantaneous efficiency point ) you will match the “projected range” value nearly exactly.
@Zoomit is correct.
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SomeJoe7777
Marginally-Known Member
The guy is just being argumentative. The post you referred to, a post I made earlier in the thread, and a few others all explain this, and he still doesn't understand. And he gave my post a disagree on top of it. Looks to me like he's just trolling.
AlanSubie4Life
Efficiency Obsessed Member
I think (charitably at least) that the disagree was because the question was about the instantaneous result from the graphs, and why that would be different over the different periods (rather than the average). Giving a Disagree seems a bit strong, but oh well.
SomeJoe7777
Marginally-Known Member
Well, that's the thing, there is no such thing as an instantaneous result -- the projected range number is an average over some time period. On the "Average range" setting, the time period is the whole graph, on the "Instant range" setting the time period is the last sample (or possibly last few samples) -- that's a much shorter time period, but still different between the different graphs because each graph has a different resolution and different sample period.
I'm not sure why this isn't kind of obvious, but the point is that it's been covered in numerous places in this thread, so I fail to see where any confusion would lie.
Further, as the time period is so short, the usefulness of the "Instant range" projected number is really low. It changes wildly depending on the driving conditions, so how does that help anyone?
AlanSubie4Life
Efficiency Obsessed Member
Brando
Active Member
warning: I'm not an owner
If you have a formula/equation/algorithum and change the variables 5/20/30 you would expect the results to change, right?
If you have a formula/equation/algorithum and change the variables 5/20/30 you would expect the results to change, right?
AlanSubie4Life
Efficiency Obsessed Member
Not if it's set to instantaneous result. But in fact, the answer to this question is that instantaneous is not instantaneous. There is a different fairly short averaging window for 5/15/30 instantaneous settings. And you can see exactly what it's doing based on where the dot is.
AlanSubie4Life
Efficiency Obsessed Member
I like how you're not an owner, but you disagree. Yet basically I agree with what you are saying.
There is a formula. It's well known. If the instantaneous result in the three different instantaneous windows (what does instantaneous mean for 5/15/30 miles, anyway???) were the same, the formula result WOULD be the same. Because the input to the formula would be the same.
The inputs to the formula are:
Constant for the vehicle.
Rated miles remaining.
Recent efficiency. **** <= This changes.
Projected range = Constant * Rated Miles Remaining / Recent Efficiency
The recent efficiency is all that changes when you change this setting. Because "instantaneous" does not give the same point efficiency value for all three settings, it gives different results. This is because it's not truly instantaneous; it's an average over a very short window (not 5/15/30 miles) of your recent efficiency. But the length of that window varies depending on your setting.
Furthermore, the car shows you, with a dot (not labeled but you can easily estimate its position), exactly what value this "Recent Efficiency" is. Just watch that dot as you change the instantaneous window. Then plug it into the formula, and it will exactly match what the car is telling you. You can't though, since you don't own the car.
I guess this 2-year-old thread was resurrected just to be disagreeable.
By the way, the video you linked is wrong in many ways. He says the line is at 225Wh/mi (with no evidence). It's not. You can tell he has an LR RWD from the results. The line is at 239Wh/mi. And the calculations on that screen show that the constant is 234Wh/rmi (that's what it is for the LR RWD!). It's easy to verify if you don't believe me. Just do the math. The video is also completely illegible even in HD mode so you can't read the numbers.
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The word instant is incorrect. It should be projected range based on the last 5/15/30 miles.
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