SageBrush
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 2:02 am

cwerdna wrote:
Wed Aug 07, 2019 12:05 am
Having the Leaf GOM turn to --- miles and eventually the % SoC display to ---% I'd argue is somewhat preferable to running out w/a range estimator showing miles or sometimes double-digit miles supposedly available. The former at least creates a sense of urgency and can convey "all bets are off", you'd better charge now!
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Bjorn's reports make it clear that no usable battery reserve exists below zero SoC. Mangling that observation into saying that the range remaining is "GOM-ish" is FUD. The meter displays SoC* and is highly accurate and occasionally imprecise to within a couple percent. Battery SoC is a derived quantity from coulomb counting and voltage measurement; neither are completely immune to environmental variables. That is the nature of batteries. The LEAF GOM is a different matter entirely since it relies on recent consumption rates.

* or EPA miles remaining = SoC multiplied by a constant -- user decides
Last edited by SageBrush on Wed Aug 07, 2019 3:02 am, edited 1 time in total.
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cwerdna
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 2:10 am

SageBrush wrote:
Wed Aug 07, 2019 2:02 am
cwerdna wrote:
Wed Aug 07, 2019 12:05 am
Having the Leaf GOM turn to --- miles and eventually the % SoC display to ---% I'd argue is somewhat preferable to running out w/a range estimator showing miles or sometimes double-digit miles supposedly available. The former at least creates a sense of urgency and can convey "all bets are off", you'd better charge now!
.
Bjorn's reports make it clear that no usable battery reserve exists below zero SoC. Mangling that observation into saying that the range remaining is "GOM-ish" is FUD. The meter displays SoC* and is highly accurate. But not always. Battery SoC is a derived quantity from coulomb counting and voltage measurement; neither are completely immune to environmental variables. That is the nature of batteries.
You're contradicting yourself. We've already established that people have continued going past 0 (case A). And, we've established numerous cases of people running out despite whole numbers, sometimes double digits of miles showing being left (case B).

Sounds like a form of GOM to me. Yes, it works totally differently than Leaf's crap GOM but sounds like a GOM to me when near dead, and arguably worse in behavior near the bottom with case B.

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SageBrush
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 3:27 am

cwerdna wrote:
Wed Aug 07, 2019 2:10 am

Sounds like a form of GOM to me. Yes, it works totally differently than Leaf's crap GOM but sounds like a GOM to me when near dead, and arguably worse in behavior near the bottom with case B.
Do you call the LEAFspy display of Ahr and SoC a GOM ? They are affected by the same environmental variables as the SoC meter in the Tesla. Probably not, because GOM was coined to highlight the uncertainty of range remaining displayed in a LEAF that results from use of recent consumption. LEAFSpy reports SoC and Ahr, where SoC is a derived quantity. Tesla reports SoC in much the same fashion.

I suppose we could argue which SoC is more accurate and precise but they both strike me as pretty similar -- accurate over time and periodically imprecise to within ~ 3% in the Tesla and ~ 5% in the LEAF. Smaller batteries have less range discrepancy, all else being equal. So e.g. a Tesla Model 3 may be off by up to 10 miles (3% of 325 miles) while a degraded LEAF may be off "only" 3.0 miles (5% of 60 miles.)
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WetEV
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 10:34 am

SageBrush wrote:
Wed Aug 07, 2019 3:27 am
Do you call the LEAFspy display of Ahr and SoC a GOM ? They are affected by the same environmental variables as the SoC meter in the Tesla. Probably not, because GOM was coined to highlight the uncertainty of range remaining displayed in a LEAF that results from use of recent consumption. LEAFSpy reports SoC and Ahr, where SoC is a derived quantity. Tesla reports SoC in much the same fashion.
GOM far predates the LEAF. I remember hearing the term in the 1970's, and have found web references to it from the 1990's. As the people that I heard it from were WW2 vets, I suspect it goes back to the 1945 or before.

http://www.renepotvin.com/cal.htm

The Tesla's range estimate is a GOM.
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 11:18 am

cwerdna wrote:
Wed Aug 07, 2019 12:05 am
Having the Leaf GOM turn to --- miles and eventually the % SoC display to ---% I'd argue is somewhat preferable to running out w/a range estimator showing miles or sometimes double-digit miles supposedly available. The former at least creates a sense of urgency and can convey "all bets are off", you'd better charge now!
The sense of urgency is conveyed in the Tesla in a more meaningful way: as the displayed range turns to orange at about (I think) 20% SOC and then red at about 10% SOC. I'd rather see a red "20 miles" than a meaningless "---".
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 11:53 am

WetEV wrote:
Wed Aug 07, 2019 10:34 am
The Tesla's range estimate is a GOM.
No, it isn't a range estimate or a GOM. As others have pointed out above, it is a fuel gauge and can be displayed in SOC percent or EPA rated miles times SOC, whichever one prefers. It doesn't vary with driving conditions but just reports SOC. SOC measurements are subject to some error so it isn't necessarily accurate, although it is generally good enough for most uses. I've been down to 2-3% but try not to go lower than that because I'm not interested in experimenting with how low I can really get. I always display my fuel gauge in percent rather than "rated miles."
cwerdna wrote:
Wed Aug 07, 2019 12:05 am
That's why I put it in quotes. Although it doesn't behave like the GOMs on Leafs and Bolts, running out when a Tesla "GOM" reads above 0 makes it ummmm... GOM-like. And, if your efficiency if worse than whatever miles/kWh (or Wh/miles) constants Tesla chose, the range meter or whatever will decrease by more than the # of miles driven.

Having the Leaf GOM turn to --- miles and eventually the % SoC display to ---% I'd argue is somewhat preferable to running out w/a range estimator showing miles or sometimes double-digit miles supposedly available. The former at least creates a sense of urgency and can convey "all bets are off", you'd better charge now!
One big difference when using Navigation is that it gives the projected remaining energy at the destination — in percent SOC — and then updates this figure in real time as one drives. If the battery percent at the destination is dropping — from dealing with a headwind, for example — one can slow down early on in the trip until it stabilizes. Tesla Nav also advises a reduced speed ("Stay below 70 mph") if consumption becomes greater than projected for the route and the car might not make it. On my car this kicks in when the projected energy at the destination hits 5%. Navigation does factor in elevation changes and typical speeds for the initial route estimate but can't predict the weather — that's why the driver needs to keep an eye on the projected energy left at the destination.

With all these navigation aids, there isn't really any reason to drive down to 0% unless one just isn't paying attention. It happens but is uncommon. Much like running out of gas in an ICE car because one didn't remember to check the fuel gauge.
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SageBrush
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 2:47 pm

dgpcolorado wrote:
Wed Aug 07, 2019 11:53 am

With all these navigation aids, there isn't really any reason to drive down to 0% unless one just isn't paying attention. It happens but is uncommon. Much like running out of gas in an ICE car because one didn't remember to check the fuel gauge.
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EXACTLY. People who have not experienced Tesla just cannot grasp how well range matters are handled. My wife is a good test subject because she still struggles with basic energy units and would not volunteer for mental arithmetic ... yet she feels no range anxiety *at all* with our Tesla.

Why ?
1. She enters a destination
2. She stops at a supercharger if the car says so.

End of drama
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 3:06 pm

dgpcolorado wrote:
Wed Aug 07, 2019 11:53 am
WetEV wrote:
Wed Aug 07, 2019 10:34 am
The Tesla's range estimate is a GOM.
No, it isn't a range estimate or a GOM. As others have pointed out above, it is a fuel gauge and can be displayed in SOC percent or EPA rated miles times SOC, whichever one prefers. It doesn't vary with driving conditions but just reports SOC. SOC measurements are subject to some error so it isn't necessarily accurate, although it is generally good enough for most uses.
I do agree that a percentage estimate is not a GOM. Rated miles, an estimate of how far the car can go under EPA conditions, is a GOM.

The original use of the term GOM had nothing to do with electric cars or driving conditions.

Tesla has a far better GOM than the LEAF. But that doesn't make it not a GOM.
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SageBrush
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Re: Official Tesla Model 3 thread

Wed Aug 07, 2019 3:20 pm

WetEV wrote:
Wed Aug 07, 2019 3:06 pm
dgpcolorado wrote:
Wed Aug 07, 2019 11:53 am
WetEV wrote:
Wed Aug 07, 2019 10:34 am
The Tesla's range estimate is a GOM.
No, it isn't a range estimate or a GOM. As others have pointed out above, it is a fuel gauge and can be displayed in SOC percent or EPA rated miles times SOC, whichever one prefers. It doesn't vary with driving conditions but just reports SOC. SOC measurements are subject to some error so it isn't necessarily accurate, although it is generally good enough for most uses.
I do agree that a percentage estimate is not a GOM. Rated miles, an estimate of how far the car can go under EPA conditions, is a GOM..
.
The important difference is that it is trivial to calculate SoC from the Tesla range, while it is impossible in a LEAF

Tesla *does* have a GOM if you will (completely separate from the SoC/EPA-miles display) that attempts to estimate destination SoC. It is remarkably accurate because it knows topography and with driving takes speed and weather into account. The algorithm is brilliant -- try to not confuse it with the SoC gauge.
2013 LEAF 'S' Model with QC & rear-view camera
Bought Jan 2017 from N. California
Two years in Colorado, now in NM
03/18: 58 Ahr, 28k miles
11/18: 56.16 Ahr, 30k miles
09/20: 54.3 Ahr; 38k miles
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Re: Official Tesla Model 3 thread

Sat Aug 10, 2019 12:59 pm

SageBrush wrote:
Wed Aug 07, 2019 3:20 pm
The important difference is that it is trivial to calculate SoC from the Tesla range, while it is impossible in a LEAF

Tesla *does* have a GOM if you will (completely separate from the SoC/EPA-miles display) that attempts to estimate destination SoC. It is remarkably accurate because it knows topography and with driving takes speed and weather into account. The algorithm is brilliant -- try to not confuse it with the SoC gauge.
This.

Several years ago the algorithm tended to underestimate actual energy use at highway speeds of 70 mph or higher (speed limits in the Intermountain West are 75 or 80 mph), then a firmware update improved it. Since the update it has been amazingly accurate for normal driving conditions. The real-time update of estimated SoC at the destination gives feedback to the driver about actual driving conditions (wind, snow, whatever). If it is dropping one slows down or selects a nearer charging stop. If it is stable or increasing, the usual scenario, there is nothing to worry about.

The algorithm also lets the driver know when he/she has charged enough and can continue on with the trip — it is faster to charge just enough to get to the next Supercharger Station, plus a small "buffer" (reserve), because the charge rate tapers as the battery fills. One can, of course, continue to charge longer to build a bigger buffer before leaving, if the weather looks unfavorable. Otherwise, the Tesla suggested leaving time is usually good enough. I often find that the car is ready to go before I am.

Image
^ An example of the estimated SoC at destination in my S (the Model 3 can show much the same information on its horizontal screen). In this example I am doing a bit better than the originally estimated SoC at the destination because my green line actual is above the grey line original estimate. It isn't necessary to display this plot because the SoC percentage is also displayed in the navigation directions (upper left box). Again, this SoC estimate is updated in real time as one drives and is very helpful in tracking actual energy usage on a trip. [The vertical dashed line on the navigation map is the Utah/Colorado border.]
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