WetEV
Well-known member
WetEV said:
Porsche Taycan - A 300 mile EV
- Thread starter lorenfb
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Help Support My Nissan Leaf Forum:
Sagebrush, perhaps you should go back and hang out with the geniuses at the Tesla forums. We really don't deserve your wisdom.
Seriously, we don't.
Seriously, we don't.
GRA
Well-known member
Personally, the most important values to me while charging is how long it will take me to add 'X' kWh and how many kWh are in the battery, as my efficiency varies so much on my trips depending on conditions that any estimator, while helpful, is likely to be of limited accuracy. I allow myself large reserves accordingly, although naturally the more experience I have with a particular model in a variety of conditions, the more accurate my estimate of needed energy will be.
For example, on my recent roundtrip in a Bolt from the Bay Area over to the east side of the Sierra, my efficiency varied from a low of 1.69 mi./kWh to a high of 22.0 mi./kWh on different legs in different terrain and conditions, with an average of 3.1 mi./kWh [Edit: Should be 3.57 kWh for the full trip] O/B (uphill) and 4.9 mi./kWh [4.94 m/kWh] I/B (downhill) [Note, the Bolt provides kWh used since last 'full' charge, with the level of 'full' being settable]. But conditions were unusually benign (a heat wave that limited my need to use heat), and I would expect to have considerably lower efficiency in cooler temps, especially given the Bolt's lack of a heat pump.
And since anyone may drive differently than me and have different climate control requirements, their estimate of how many kWh they need for a given trip will be different from mine. AIUI, Tesla's Rated range is a value based on a fixed efficiency, essentially a conversion of energy stored (% SoC, if linear, is another conversion), so I see no reason not to provide the actual energy value instead. But, having learned math in a pre-calculator era I can do basic math in my head and am also comfortable with electrical units, so people who lack those skills may find rated range more useful, applying their own appropriate modifier to that to arrive at the rated range they need for a given trip.
For example, on my recent roundtrip in a Bolt from the Bay Area over to the east side of the Sierra, my efficiency varied from a low of 1.69 mi./kWh to a high of 22.0 mi./kWh on different legs in different terrain and conditions, with an average of 3.1 mi./kWh [Edit: Should be 3.57 kWh for the full trip] O/B (uphill) and 4.9 mi./kWh [4.94 m/kWh] I/B (downhill) [Note, the Bolt provides kWh used since last 'full' charge, with the level of 'full' being settable]. But conditions were unusually benign (a heat wave that limited my need to use heat), and I would expect to have considerably lower efficiency in cooler temps, especially given the Bolt's lack of a heat pump.
And since anyone may drive differently than me and have different climate control requirements, their estimate of how many kWh they need for a given trip will be different from mine. AIUI, Tesla's Rated range is a value based on a fixed efficiency, essentially a conversion of energy stored (% SoC, if linear, is another conversion), so I see no reason not to provide the actual energy value instead. But, having learned math in a pre-calculator era I can do basic math in my head and am also comfortable with electrical units, so people who lack those skills may find rated range more useful, applying their own appropriate modifier to that to arrive at the rated range they need for a given trip.
GRA,
I agree with your example. My point for you is that a car with lower (or higher) efficiency will shift your calculation.
E.g,,
Say you know that driving a Bolt on your mentioned drive results in the fuel consumptions you mentioned, and 20% lower consumption in a Model 3. You would naturally adjust your mental calculations to account for the difference in car efficiency. Charging stop times still vary dramatically from place to place, but you *always* account for differences in car efficiency.
It is no different than deciding to take on more kWh before a hill. The Wh/mile is integral to the assessment of how many kWh to take on for the next leg of the trip. The Wh/mile coming up can be a hill, or headwind, or gravel roads, or it can be vehicle efficiency. It makes no more sense to ignore vehicle efficiency than it does to ignore a mountain.
I agree with your example. My point for you is that a car with lower (or higher) efficiency will shift your calculation.
E.g,,
Say you know that driving a Bolt on your mentioned drive results in the fuel consumptions you mentioned, and 20% lower consumption in a Model 3. You would naturally adjust your mental calculations to account for the difference in car efficiency. Charging stop times still vary dramatically from place to place, but you *always* account for differences in car efficiency.
It is no different than deciding to take on more kWh before a hill. The Wh/mile is integral to the assessment of how many kWh to take on for the next leg of the trip. The Wh/mile coming up can be a hill, or headwind, or gravel roads, or it can be vehicle efficiency. It makes no more sense to ignore vehicle efficiency than it does to ignore a mountain.
jlv
Well-known member
That's not the case. "Miles added" is the exact number of rates miles for that car ("kWh added" * "rated miles / kWh"). That ratio on the right is is different per Model and configuration (e.g,. a more efficient Raven Model S vs. the one I have). But it's still a firm number. There's no guess or range involved; every time a specific number of kWh are added the car will give the corresponding number of miles added.LeftieBiker said:
If it really bothers you, you can switch the car to display SOC instead (and some people prefer this). But when I'm thinking of driving to my destination, the road sign tells me miles and I'd personally rather deal in my head with miles. If I'm doing 60MPH, I'll get close to rated miles. If I'm doing 75MPH, then I know I'll get 80% rated miles. If it's raining, I'll drop another 10% off. Etc.
So Tesla has managed to change the laws of physics? If I forget to put air in the tires and ignore the warnings, I'll get the same range with 20psi as I would with 40? Same range with a headwind as with a tailwind? The same range if I decide to race a Bolt as I'd get if I drive like a Granny? I can certainly see the advantage of thinking in terms of miles rather than %SOC, but I still don't see how that metric can be dead accurate. My housemate thinks in terms of miles of range too, but she doesn't believe that if the car says 74 miles that she can safely drive 74 miles, even though the Gen II GOM is pretty accurate for us.
jlv
Well-known member
:? I don't know why you went off on a rant like that.LeftieBiker said:
In a Tesla, there is a direct, constant correlation between RM and kWh. You can choose to see rated miles on the dash or you can choose to see %SOC. There's no guess. You it as you want (or not).
DougWantsALeaf
Well-known member
Correct, just remember that RM changes with software releases and should not be used as a marker for guessing battery degradation.
cwerdna
Well-known member
This is exactly why I said this is Tesla-centric. You're using an unpublished constant and the miles figure will only be correct if you achieve the unpublished miles/kWh value being used.jlv said:
The GOMs in my Leaf and Bolt do NOT work this way. So, thus the number of miles the GOM has gone up (if I even bothered to look) is of questionable to no value. ChargePoint's app in a few places in their UI makes a guess using # of miles based upon some unpublished constant for the vehicle you have selected but again, it's of no use unless I drive at that unpublished efficiency and bothered to select the right vehicle to begin with (since I have two). Also, right now, I almost never charge on ChargePoint.
And, there's no UI in either of my cars to tell me "miles" per time unit for charging speed. Again, that's a Tesla thing.
I can't speak to the GOMs, range estimators or whatever for all other EVs.
GRA
Well-known member
SageBrush said:
Of course, and that's one of the variables that can probably only be acquired by experience with the particular model car in particular conditions, although knowing its efficiency in a given set of conditions may be useful if they are close to the ones you encounter.
I wasn't angry, just trying to show why saying that X miles acquired per charge can't always be right unless the route, weather and driver are always the same. This must be like one of those visual illusions in which half the people looking see one thing, and the other half another. I get that Tesla has a better range estimator. What I don't get is why I should start worshiping it as my new god. I'm perfectly happy with my current (heh) god, Reddy Kilowatt.
cwerdna
Well-known member
I spoke to the Bolt and Taycan driver towards the end of my free EA session (https://mynissanleaf.com/viewtopic.php?p=600099#p600099). I pinged him after I began my free EA session.
He brought his Bolt to charge for free. He briefly showed me a video he made of him charging from 1% to a bit past 80% on a 350 kW DC FC. He said his peak rate was 260 kW and he got from 1% to a bit past 80% in 23 minutes. He also had the battery temps, starting at 92 F and ending past 120 F (IIRC). He mentioned the dash displays the numeric battery temp.
He brought his Bolt to charge for free. He briefly showed me a video he made of him charging from 1% to a bit past 80% on a 350 kW DC FC. He said his peak rate was 260 kW and he got from 1% to a bit past 80% in 23 minutes. He also had the battery temps, starting at 92 F and ending past 120 F (IIRC). He mentioned the dash displays the numeric battery temp.
coleafrado2
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120F? Ouch
Tesla heats up the battery to ~ 120F on purpose during very fast charging to mitigate plating. That is not an ouch, the ouch is if the battery stays hot after charging.coleafrado2 said:
The LEAF does the double-OUCH:
Plating during charging, then
Extended time at a high temperature
coleafrado2
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SageBrush said:
In that case it should start out as hot as possible (max current) and taper temperature with current... ending a 260 kW charge at 120F means there's nowhere near enough cooling
There are more details that go into this -- it is not as simple as either of us wrote, and some of the information is proprietary. SoC certainly plays a part. The general point stands though, that really fast charging needs a TMS that can ramp both heating and cooling during the charging cycle and shortly afterwards to mitigate battery degradation.coleafrado2 said:
coleafrado2
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SageBrush said:
A still life may not be accurate down to the microarcsecond, yet we can still enjoy it
GRA
Well-known member
WetEV
Well-known member
Or read the C&D version directly at
https://www.caranddriver.com/features/a37419238/pikes-peak-mountain-2021-porsche-taycan-4s/
https://www.caranddriver.com/features/a37419238/pikes-peak-mountain-2021-porsche-taycan-4s/
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