Energy screen drive versus consumption inconsistency

[3sr+buyer]

When driving in a way that the drive tab of the energy screen says that I am using 1% less than rated about 30 miles since the start of the trip, showing the consumption tab shows the 30 mile average consumption about 12% below the rated line.

This difference seems to fairly consistent. What is the reason for this difference? Is it because the drive screen adds in charging cost to the energy used, or something else?

 

[derotam]

Just guessing here without looking at the screen to see terminology.... Are you doing a navigation? Are you sure that Drive tab isn't showing the 1% as 1% less than EXPECTED for the routed drive?

 

[jdcollins5]

When driving in a way that the drive tab of the energy screen says that I am using 1% less than rated about 30 miles since the start of the trip, showing the consumption tab shows the 30 mile average consumption about 12% below the rated line.

This difference seems to fairly consistent. What is the reason for this difference? Is it because the drive screen adds in charging cost to the energy used, or something else?u

Delete

 

[3sr+buyer]

Just guessing here without looking at the screen to see terminology.... Are you doing a navigation? Are you sure that Drive tab isn't showing the 1% as 1% less than EXPECTED for the routed drive?

Not using navigation.

 

[AlanSubie4Life]

When driving in a way that the drive tab of the energy screen says that I am using 1% less than rated about 30 miles since the start of the trip, showing the consumption tab shows the 30 mile average consumption about 12% below the rated line.

This difference seems to fairly consistent. What is the reason for this difference? Is it because the drive screen adds in charging cost to the energy used, or something else?

Can you post some pictures?

I am not sure what you are asking or the discrepancy you are seeing. The Drive tab I thought was referenced to “expectations,” not to rating. But I have not played with it much so I could be wrong. And not sure exactly how they come up with the expectation. I think I understand your question but pictures would help.

It does say “consumption vs. rated” so I see what you are saying. Still, side-by-side images would help.

One thing to keep in mind is that the “rated line” is always 5Wh/mi (so typically about 2-3%) above the actual rated value (for my car it is at 250Wh/mi and the rating is 245Wh/mi).

Additionally the *displayed* mile usage in the car is for miles with 4.5% less energy content than the rated due to the buffer. So if I’m consuming at the “rated” line of 250Wh/mi (for my car), I’d expect displayed mile usage of 250/234 = 1.068, 6.8% higher than that “rated” line. But just 4.7% (245/234) higher than *actual* rated. I would have to look at this drive tab more to see how it actually behaves.

You can do your own calculations for your specific vehicle. I don’t know which SR+ (unicorn LFP, or the heat pump NCA, or what) you have.

 

[3sr+buyer]

 

[3sr+buyer]

 

[3sr+buyer]

The above may not be the best comparison, since the last drive was 20 miles instead of 30 miles, but the consumption graph tends to show significantly better than rated when the drive says that it is slightly (1-2%) worse or better than rated.

Car is a 2022 model year with LFP.

 

[AlanSubie4Life]

Car is a 2022 model year with LFP.

SR+ I assume?

Anyway with that assumption:

Is your US made SR+ LFP charging to 253 or 262?

In the European LFP vehicle, I understand that the rated energy per mile is essentially identical to the US NCA vehicle. So I do not believe there is any reason to believe that the US LFP vehicle will be different. It appears the US and European vehicles both already have the increased capacity...

teslamotorsclub.com

54.7kWh degradation threshold.
55.1kWh FPWN
262 rated miles when new (?).

So that means:
Rated line is at 214Wh/mi
Constant is 54.7kWh/262rmi = 209Wh/rmi

Energy per actual displayed mile is: 209Wh/rmi*0.955 = 200Wh/rmi
Assuming your buffer has not gone nuts (LFP!).

You did 198Wh/mi, so I would expect the display to indicated 1% better than rated consumption.

Seems pretty close though as you say we need to have a 30-mile observation window to actually do a comparison. It looks like your 20-mile average may have been slightly higher than 198Wh/mi. Which would align perfectly.

You could switch to 15-mile display if you want to play with this and see if consistent.

If you actually have a 2022 RWD LFP we can adjust these numbers though they are pretty similar (rated line is around 220Wh/rmi I think). Seems like you have SR+ though.

Also you must live somewhere really quite flat?

. But just 4.7% (245/234) higher than *actual* rated.

Scratch this comment above. Not sure what I was talking about with this sentence. Other stuff is correct I think.

If I consume at 250Wh/mi I’d expect the Drive screen to tell me I am consuming 6.8% more than rated.

 

[3sr+buyer]

The car is a 2022 RWD with LFP battery had an original rated range of 272 miles, which it showed at 100% when new. The car currently shows 265 rated miles when charged to 100%.

The rated line on the consumption graph appears to be at around 227Wh/mi, based on seeing the rated line and dashed line merge when the display shows 227Wh/mi.

 

[AlanSubie4Life]

The rated line on the consumption graph appears to be at around 227Wh/mi, based on seeing the rated line and dashed line merge when the display shows 227Wh/mi.

Yes that is correct. 60.5kWh degradation threshold. 272 miles. So 222Wh/mi rated value.

So the line would be at 227Wh/mi.

So adjusting the numbers above:
222Wh/mi *0.955 =212Wh/mi displayed energy content.

Again this assume the buffer is not confused (charge to 100% a couple times!). It can expand, and lower this value.

So it does seem like there could be a few % discrepancy (it doesn’t look to me like your 20-mile average was 212Wh/mi) but we need a precise window (30 miles vs 30 miles or 15 vs. 15) to say whether there is.

I’ll check on my car on my way home and see how it aligns. Looks conceivable it could, or there could be some misalignment. Not sure. I don’t have to worry about buffer expansion.

 

[dhrivnak]

The consumption graph, I do believe shows driving only. It does NOT show HVAC or battery warming or other draws like lights and radio. As such I find the consumption graph misleading and overly optimistic.

 

[AlanSubie4Life]

So I think it all aligns pretty well. It does seem that the consumption graph does not match the trip meter. So that's part of it. If you use the trip statistics, and also take into account that the trip meter reads about 1% low typically (as metered by SMT and other methods), then it all works out.

My car has rated line at 250Wh/mi, rating is 245Wh/mi, and energy per displayed mile (what matters!) is 234Wh/mi.

This trip used 368Wh/mi (which is about 371.7Wh/mi actually as mentioned above).

So that means I should have used: 371.7Wh/mi / 234Wh/rmi = 1.588rmi/mi, so for this 15.0mi trip: 1.588rmi/mi*15mi = 23.8 rmi.

The trip actually consumed 24.0 rated miles. So that's off by 0.8%. Fairly close though maybe there is still some discrepancy.

You can see here the 15-mile consumption does not match the trip meter (359Wh/mi vs. 368Wh/mi, a big difference) as mentioned above. This is a big part of the reason probably for the original question & noted discrepancy.

I have yet to make sense of the consumption "expectations" vs. the rated. The way I read this, the car had a "rating" of 1.2 miles of Climate use for this drive (I was 0.9miles above with 2.1 miles of usage, so the "rating" was 1.2miles). I'm not sure if that is a baseline built into the vehicle rating (what was measured in EPA testing) or what. Maybe someone can explain how those number are derived but it's not the original question here.

The consumption graph, I do believe shows driving only. It does NOT show HVAC or battery warming or other draws like lights and radio. As such I find the consumption graph misleading and overly optimistic.

I hadn't noticed this in the past, but maybe that is the case - I hardly ever use HVAC so maybe I never noticed the discrepancy vs. the trip meter seen above. I'll have to repeat the above experiment with the HVAC & other things off for the same trip to see whether that brings them into better alignment.

 

[derotam]

The consumption graph, I do believe shows driving only. It does NOT show HVAC or battery warming or other draws like lights and radio. As such I find the consumption graph misleading and overly optimistic.

That is not entirely correct. It does account for all energy usage while in a driving mode(drive, hold, reverse...NOT park)

 

[AlanSubie4Life]

That is not entirely correct. It does account for all energy usage while in a driving mode(drive, hold, reverse...NOT park)

It definitely accounts only for energy used while not parked. That has been the case for the trip meter too.

However, something is wrong with it as you can clearly see above. I’ve never noticed this discrepancy before, so I do wonder whether it got broken somehow. (You can see the 15-mile trip meter is nowhere near the 15-mile consumption graph.)

Or maybe it was always this way (I had not noticed before and I thought previously that these aligned.)

I would like to compare for a flatter graph, to make sure that it isn’t being thrown off by end effects, but it is 15.0 miles vs. 15.0 miles so seems like it should be ok. Basically impossible for me to have flat consumption graphs. Also should compare 30-mile trip to 30-mile consumption.

I also want to do a couple other things to see if it’s possible to get better alignment.

 

[AlanSubie4Life]

I took a couple more pictures (will post later since I continue to have no edit capabilities in the mobile version of this site for some reason).

I do think there may be some discrepancy but not sure if it is just rounding error or some other source (like expected consumption is altered by conditions or something and does not represent a constant slope corresponding to a fixed rating).

This time the trip meter and consumption page were in better agreement. I had climate off (I’m not convinced yet that the consumption screen does not count this though - I know I have seen it counted before!).

But there was still a couple percent difference:

Consumption said 209Wh/mi, trip said 211Wh/mi. Rated line is 250Wh/mi, actual displayed energy content is 234Wh/mi as mentioned.

So after increasing those values by 1% (known undercount) would expect:

211Wh/mi*1.01 / 234Wh/mi = 0.91 so 9% better.

But used 13.9 vs. expected 15.1 (8% better).

Close but not quite in alignment. Will have to look at longer drive results.


Anyway, for your RWD a key contributor to your observed mismatch is that your rating is 212.4Wh/mi (displayed: 60.5kWh/272mi * 0.955) assuming your buffer has not expanded. Not 227Wh/mi (the position of the line).

You need to get about 210Wh/mi (correcting for 1% loss) on the trip meter for “parity” mile-for-rated-mile rolloff. (This is easily verified on a long trip segment; just scale it (usage in Wh/mi * distance / 210Wh/rmi) if you have a different consumption and you’ll see this aligns perfectly. Unfortunately Tesla makes it annoying to get three sig figs these days so you’ll have to drive 100 miles to do this on the trip meter, or carefully extract the distance with three sig figs from the new drive screen and piece the info together.)

 

[derotam]

I suspect either a difference in rounding used in different views and/or a granularity/calculation point difference between views. There has been issues in the past with a discrepancy even within the consumption graphs depending on whether you choose 5, 15 or 30 mile views.

Definitely a bit of work to attempt to track down where the issue might be....and then one software update can change it all, haha.

I don't like the elevation part of the new drive energy usage when routing...that should be Zero, unless the are using elevation data that is different than reality.

 

[derotam]

That is not entirely correct. It does account for all energy usage while in a driving mode(drive, hold, reverse...NOT park)

I will add that it CAN account for a certain amount of energy while in park during the calculation time period that encompasses the switch to a driving mode....which is why longer drives are better for evening out various small anomalies.

 

[AlanSubie4Life]

I don't like the elevation part of the new drive energy usage when routing...that should be Zero, unless the are using elevation data that is different than reality.

I think they are just trying to show people how much elevation contributes to deviations in usage, and this does the job. Or are you talking about the trip screen (which should account for it and on that view should be about zero impact, agreed)? I haven’t seen how that is tabulated and displayed. I would add that even on that display, the car does not know the actual weight of your car and passengers, so a heavy car would underperform and a very light car would overperform even accounting for elevation data.

I assume the expection for usage on the trip view is some non-zero number (while on the Drive Current Drive view it is zero). So if you have a very heavy car (or are towing) it would show big deviations here still, but relative to the expectation, rather than relative to zero.

(With a very heavy car or when towing you’d overperform expectations on downhills of course!)

I suspect either a difference in rounding used in different views and/or a granularity/calculation point difference between views.

I agree. The discrepancy last night that I had was huge though. 359 vs. 368. But I do wonder about how I treated the beginning of the drive. Sat in drive stationary for a minute or two with heat on, then put in park, got out of car, got back in (to be sure trip meter for “Current Drive” got reset) But maybe it did not reset the trip.

I am pretty confident it counts heat use (and all use) but will verify tonight to be sure.

 

[AlanSubie4Life]

I don't like the elevation part of the new drive energy usage when routing...that should be Zero, unless the are using elevation data that is different than reality.

I checked this out a bit more, and it works as expected:

0 for the No trip version (since last charge). Since it has no idea what to expect.

And the baseline expectation for a given weight and set of parameters for any other planned drive. If you don’t match those you’ll do better/worse on the uphills and (most likely) worse/better on the downhills. And the difference vs. that baseline will be displayed.

To get the expectation, subtract second column from the first. (Actual - Expected = Difference, So Actual - Difference = Expected)

——

For the “rated” mode, it does seem that there is a baseline expectation for climate consumption and accessory consumption which is partitioned in the rated result. I wonder how they arrived at this and whether it really reflects EPA test measurements of these contributors (they do measure it during test). And I wonder for different vehicles types whether the % partitioned to each use are different. (For my car it seems to be 8% for climate and ~6.7% for “everything else” category, see above.).

However I don’t think that would be the root cause of the original noted discrepancy here.