This is why you can't get 'rated range'

[shred86]

Do you know if TM-Spy provides the readout on the phone for those parameters, or just the charts? I think Scan My Tesla does report all those values like SOC, nominal full pack, usable full, etc. I have the cable and Bluetooth attachment and am wondering if TM-Spy will give me what I am looking for. One thing I want to determine is what my designated buffer size is. Since I have a 70D, I think it is supposed to be 2.4 kWh, not the usually reported 4 kWh.

TM-Spy appears to report "Nominal Full Pack", "Expected Energy Remaining" and "SOC UI", all of which are directly reported on the CAN bus. In the attached screenshot you can see a screen capture of TM-Spy about 10 seconds after I logged some 0x382 CAN ID bus data. I didn't get any 0x302 data but every time I have, it matches exactly with the reported "SOC UI" on the CAN bus with what's being displayed as "SOC" in TM-Spy. The screenshot with the black background and CAN bus data is just me using a simple Python script I made to translate the raw CAN bus data frame logs I get from TM-Spy into a human readable format. Realize those "SOC" percentages are just calculations and not the values reported (TM-Spy only allows you to log one CAN ID at a time).

The buffer value you're looking for is reported in the 0x382 CAN ID data, so you can log the data but you'll have to convert it either manually or use something like the Python script I created. It's not reported in TM-Spy, but it is reported in Scan My Tesla.

Note: The 17 mV cell imbalance is from not having a good connection with TM-Spy. I restarted the app and with a good connection it was showing ~4-5 mV.

 

[ran349]

@shred86 Thanks for sharing the data. That explains the discrepancy between the SOC value and the remain/pack values reported on the chart. Since you have 76.2 kWh, it seems you have a good battery with only a small amount of degradation.

 

[N..8]

Once again the only way to get the Advertised EPA rated range is to go into the 4kw buffer.

 

[Rocky_H]

Once again the only way to get the Advertised EPA rated range is to go into the 4kw buffer.

For as much fine technical detail as you want to go into on this issue, it would be great if you could start referring to amounts of energy by kWh instead of kW.

 

[N..8]

Yeah my phone likes to correct and leave off the h, then by the time I read my post I can't edit it.

 

[Snerruc]

Yeah my phone likes to correct and leave off the h, then by the time I read my post I can't edit it.

As I wrote before, a lot people of get rated range or more. I typically get rated range + 10%. My current 100% charge nets 233 miles of range at 100% charged. Recently I drove 210 miles of mixed interstate, highway and city driving and still showed 45 miles of range left or 255 total .

 

[shred86]

As I wrote before, a lot people of get rated range or more. I typically get rated range + 10%. My current 100% charge nets 233 miles of range at 100% charged. Recently I drove 210 miles of mixed interstate, highway and city driving and still showed 45 miles of range left or 255 total .

As it's already been mentioned before, no one is saying you can't achieve rated range. You absolutely can and even significantly exceed it, but it depends on your Wh/m. What is being discussed is why you can't achieve the rated range when you drive at the EPA rated Wh/m, which are listed in this thread and is what your displayed rated range is based on.

 

[Snerruc]

Well,that’s not what the title says.

 

[supratachophobia]

Well,that’s not what the title says.

To be fair, should we really be calling what the dash says "rated range"? I mean, there is EPA rated range (which is what the dash starts at) and there is what the dash says. Two totally different numbers once you start driving.

 

[Rocky_H]

To be fair, should we really be calling what the dash says "rated range"? I mean, there is EPA rated range (which is what the dash starts at) and there is what the dash says. Two totally different numbers once you start driving.

I don't understand where you're coming from at all. The number is still saying that: "If you drive at the EPA rated efficiency, then you can still get this many miles."
That is still a "rated range" number. That has nothing to do with most people not driving at the EPA rated efficiency levels most of the time.

 

[David99]

Well,that’s not what the title says.

You ignore the content of the initial post, you ignore 7 pages and 126 more comments about the subject and then post a comment that makes no sense in the context of the entire discussion. I'm not sure you understand the concept of a message board.

 

[supratachophobia]

I don't understand where you're coming from at all. The number is still saying that: "If you drive at the EPA rated efficiency, then you can still get this many miles."
That is still a "rated range" number. That has nothing to do with most people not driving at the EPA rated efficiency levels most of the time.

But the number comes from EPA rated range. And since 0 miles isn't 0kwh (it's 4), then the whole idea that the dash is accurate is just bunk.

 

[shred86]

I don't understand where you're coming from at all. The number is still saying that: "If you drive at the EPA rated efficiency, then you can still get this many miles."
That is still a "rated range" number. That has nothing to do with most people not driving at the EPA rated efficiency levels most of the time.

But the number comes from EPA rated range. And since 0 miles isn't 0kwh (it's 4), then the whole idea that the dash is accurate is just bunk.

I'm not quite sure what you're disagreeing with, Rocky_H. If you have data that suggest what supratachophobia is saying is incorrect then please share because all of the data so far suggest what he's stating is correct.

If you drive at a Wh/m less than the EPA numbers, then you will achieve the displayed rated range. That's the whole point of this thread...

That being said, have the actual Wh/m to achieve the EPA numbers ever been officially released by Tesla? The data I'm using is from wk057 which I realize is directly from the car's firmware, but just more curious if it's ever been something officially published.

Anyways, I personally don't think it's a huge deal but just surprising and interesting at the same time.

 

[David99]

That being said, have the actual Wh/m to achieve the EPA numbers ever been officially released by Tesla? The data I'm using is from wk057 which I realize is directly from the car's firmware, but just more curious if it's ever been something officially published.

Yes. The car's energy graph showing the average energy consumption has a dotted line called 'rated'. In my car it is exactly at 300 Wh/mile. If I use that number (instead of what Jason found in the firmware) the discrepancy is even bigger.

 

[N..8]

Before this thread I would read how people complained about not getting the mileage. Most people would answer the thread by saying that there was things not being reported and this mystery drain was causing them not to get the rated range. Well now we see that one of the issues is that right from the get go from 99% to 0% it's being scaled to loose 6.5% (on my car) on the bottom. 4kWh is being calculated out of the Dash SOC.

 

[supratachophobia]

Before this thread I would read how people complained about not getting the mileage. Most people would answer the thread by saying that there was things not being reported and this mystery drain was causing them not to get the rated range. Well now we see that one of the issues is that right from the get go from 99% to 0% it's being scaled to loose 6.5% (on my car) on the bottom. 4kWh is being calculated out of the Dash SOC.

Exactly.

 

[supratachophobia]

I'm not quite sure what you're disagreeing with, Rocky_H. If you have data that suggest what supratachophobia is saying is incorrect then please share because all of the data so far suggest what he's stating is correct.

If you drive at a Wh/m less than the EPA numbers, then you will achieve the displayed rated range. That's the whole point of this thread...

That being said, have the actual Wh/m to achieve the EPA numbers ever been officially released by Tesla? The data I'm using is from wk057 which I realize is directly from the car's firmware, but just more curious if it's ever been something officially published.

Anyways, I personally don't think it's a huge deal but just surprising and interesting at the same time.

Not sure how else we can clearly state this...

If you drive at EPA consumption starting at 100%, you will not achieve that starting number on the dash. You will go the starting number minus 4kw divided by your EPA watts per mile, to end at zero. Or to put it in an equation:

<actual_miles_traveled_at_EPA_consumption = <starting_dash_display> - (4 / <EPA_consumption_kilowatts_per_mile>)

 

[shred86]

Yes. The car's energy graph showing the average energy consumption has a dotted line called 'rated'. In my car it is exactly at 300 Wh/mile. If I use that number (instead of what Jason found in the firmware) the discrepancy is even bigger.

Ha, that’s right. I completely forgot about that line.

 

[shred86]

Well, this new info shared by wk057 seems to explain what is going on:

Next, I actually spoke with an ex-Tesla engineer who actually worked on the BMS software early on. He explained that the 4 kWh "buffer" doesn't mean what we think it means. It was actually a kludge built in to smooth the range calculation, and to make sure you actually could hit zero miles consistently without getting stranded. On average, the actual capacity "buffer" is 2 kWh, so the code was written so that a 4 kWh window was used and scaled along with the SoC as the car discharged, adjusted and calibrated as possible based on other measurements. This was to ensure that the range calculation would never adjust abruptly, and should never (rarely) run out of capacity while rated miles were > 0. TL;DR: The actual capacity left on the table by the value of the "buffer" is targeted by the BMS to be half that much..

If I’m understanding this correctly, it’s basically what was being discussed in this thread - the buffer is slowly being rolled into the rated range calculation as the SOC decreases. We’ve seen several examples of folks at 0% displayed SOC/rated range and the BMS reported nominal energy remaining (or expected energy remaining, for those using TM-Spy) seems to be anywhere from ~2-4 kWh.

 

[supratachophobia]

Well, this new info shared by wk057 seems to explain what is going on:



If I’m understanding this correctly, it’s basically what was being discussed in this thread - the buffer is slowly being rolled into the rated range calculation as the SOC decreases. We’ve seen several examples of folks at 0% displayed SOC/rated range and the BMS reported nominal energy remaining (or expected energy remaining, for those using TM-Spy) seems to be anywhere from ~2-4 kWh.

But again, you can't drive the full rated range if you stop when the dash says zero. That's not a kludge, it's a lie.