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Battery "true" capacity for a 90D

Battery "true" capacity for a 90D

I am trying to see if anyone has answers as far as Useable battery capacity vs. stated capacity and possible reserve or re-indexing the perceived battery capacity.

I now have 153 charges logged on teslfi and 367 drives.

I have a Nov 2015 Model S 90D with 61,000 miles on it. I drive on "Range Mode" all the time with interior temp set to 19c in the winter with no heating for comfort and 22c in the summer.

I have run down to 1% and 0% rolling into charging stations based upon Tesla navigation calculations and trying to reach the suggested and navigated charging station, but never died. I have found on my last road trip that the Tesla nav ap would not consider an alternate charging station (if one was available before the point of no return) until I had gotten down to arrival at 2% or lower.

SUGGESTION FOR TESLA- I would love to have Tesla incorporate a thresh hold setting that you can set a reserve preference in the nav setting to ensure you arrive with reserve (0-15%). Basically redirect me to a closer charger if I cannot arrive with the preset threshold at the navigation Ap designated charger. Leave me some more range before you redirect at the point of no return.

I drove this last trip for 30 miles with the "Do not exceed 50mph to make your destination" before the Tesla app decided to redirect me to a charging station I was about to pass in 2 miles when the "arrive with" dipped to 2%. I intervened on 5 occasions where I would have been stranded or driving at 50mph in a 75 and 70mph zone attempting to hypemile to the next charger. I decided to interrupt the trip and charge, and was met with a "charge for 15 minutes to continue your journey" to the charging station I was directed I would make it to based upon my last charge and past 800 miles of recorded and trended driving. Basically I stopped before directed to do so, and was directed to charge for 15 minutes to make it to the previously designated charger...So I would have been stranded or doing 40mph in the right lane to make it?

Charging 0-1% - 100%
74.7-74.9 Kw @ 100% efficiency supercharging or 85% efficiency home charger

Driving - utilized Kw
74.6.74.9 Kw 100% - 0-1%

So I have recorded a half dozen charges from 0-1% upto 100% to see how much I actually charged the battery, the answer 74.7 - 74.9 Kw
Accordingly when I view the trip meter I expended exactly the same amount between charging on an uninterrupted road trip.

I drive 100+ miles daily on the highway, flat one way 50 miles at 70-80mph, returning in rush hour at 35mph in the middle 1/3 of the time with the first and last 1/3 of the trip at 65mph.

I utilize the cruise control all the time. I avg 330 w/mile and at 75Kw capacity that equates out to calculated 227 miles, but I am actually getting ~190 miles tops. This summer with everything off I consumed 75 kw and traveled 210 miles New record for distances, I avg 290w/mile.

So my question. What is the overprovisioning of the battery, or is there a limit of useable capacity? I am seeing a 17% capacity gap between my stated battery capacity and what I can charge and use. Yes i understand there are parasitic losses while driving, but if I charge at 100% efficiency from 0-100% and only charge on board 74.9Kw (supercharging and home charging - although at 85% efficiency) and my use shows exactly the same expended as charged, they where is the missing 15kw?

I would need to get my consumption down to 277 kw/mile to get 270 miles out of my 75KW of available battery. Do I need to run my battery flat (a bad thing for LiOn batts) in order to get a new reference level so the system algorithm "knows" the actual capacity of my battery?

I asked a home visit tech to run a remote battery test and he provided me all he was "authorized" to tell me...My battery was performing and had capacity "in family" with Model S 90D of similar vintage.

But I can never get a straight answer on useable capacity and why I can spend or charge more than 75Kw on a 90Kw battery.

I am still happy with the car as I don't pay for the charging for my work as I supercharge everyday on the way home, because I can't make 1.5 round trips without rolling in on the way home with 1% at the nearest charger, if I am even able to make it. When I compare what I would pay for and ICE car in maintenance and gas, the Tesla made sense for my purpose. I also use it to make the 2000 mile R/T to pick up a drop off my daughter at college, effectively making the trip for free. We pack snacks and food for the entire trip and nap in the car.

Any tips or suggestions?

Bighorn | 2020年1月16日

The 85s came with 73.7 kW available and rated mile parity was 278 Wh/m. My recollection was that the early 90s just had more silicon in the anode and not more cells. They also saw early range loss that put them close to their 85 brethren. They were also power restricted at the superchargers. Energy in should not match extracted energy as it takes 300 Wh to add a rated mile and 278 to get one back.

Bighorn | 2020年1月16日

73.7 kWh

p.c.mcavoy | 2020年1月17日

If you do a little googling for ‘Jason Hughes Tesla battery capacity’ you’ll find several articles that reference numbers which Jason Hughes has published. Hughes is a well respected Tesla hacker/expert on battery capacity and BMS and his numbers come from both doing physical tear downs of the batteries plus his ability to get inside Tesla’s code and find information others wouldn’t have a clue of how to find.

He quotes for a 90D/P90D – ~85.8 kWh total capacity, 81.8 kWh usable.

I have a mid-2016 refresh MS90D, with about 51,000 miles which I’ve owned since new. My experience is that I need to run about 274 Wh/mi to achieve 1 mile traveled per rated mile consumed. That’s not too far off the numbers you’ve also found, although I believe the refresh was a smidge more efficient than the original nosecone from info I’ve seen over the year. Either way, your experience of needing to get to 277 Wh/mi to match rated miles is in line.

I’ve logged virtually all of my charging sessions over the past 3.5 years via running VisibleTesla on my home laptop. I’m currently at about 1050 data points in my historical trend since new. I’m at about 7% apparent reduction at 51K miles. We’d all like to have 0% degradation over lifetime, but that’s not realistic.

If I take at face value your apparent usable capacity of 74.8 kWh versus the Jason Hughes 81.8 reference, that says your pack is indicating an apparent 8.5% reduction in capacity. That’s not outlandish for a 90 pack, consistent with my experience, and hence why you got the response from the mobile tech that you did.

I’ve not bothered trying to make sense of the energy added during charging numbers, but simply reference my change in apparent capacity from the displayed rated miles. I do not have any experience using TeslaFi, so do not know how they are deriving their energy added numbers. There is a value that is reported over the API from the car, but I’ve never fully made sense if that’s referenced to added to the pack or consumed from the wall. I’ve also noted that at times in different parts of Tesla’s software they appear to use different rate constants for what the Wh/mi is for 1 rated mile. That’s why I’ve chosen simply to trend indicated rated range at 100% SOC as my indicated of available capacity on my car.

Bighorn | 2020年1月17日

@pc
Jason’s numbers were never possible to achieve IRL, so I wouldn’t benchmark them.

Bighorn | 2020年1月17日

Here are his 85 figures which are about 3.5 kWh higher than original rated miles. i.e. 265 miles x 278 Wh/m

https://www.google.com/amp/s/electrek.co/2016/12/14/tesla-battery-capaci...

p.c.mcavoy | 2020年1月17日

@BH - That’s the same reference I pulled his quoted 90 pack capacity.

For my 90D, quoted rated range of 294 miles, Jason’s reported 81.8 kWh usable capacity would imply a rate constant of 278 Wh/mi.

From doing long, continuous drives, I’ve found with my MS90D that I needed to achieve somewhere 272-274 Wh/mi to equal rated range consumed.

From that I could claim Jason’s capacity is in error and overstated by a couple percent. However, it’s just a plausible that the displayed kWh consumed and average Wh/mi numbers do not reflect 100% of the energy consumed from the battery. You can find lots of debate on that point. It all comes down to none of us have a good absolute reference for Wh/mi consumed to compare the stated battery capacities with the quoted rated range numbers.

All the more reason I personally quite worrying about pack capacity in kWh and judge all of my trends on my apparent battery capacity as indicated by displayed rated range.

Not that range is much of a concern for me at the moment given my car sits 14 time zones away from me most of the time and I’ve only had the opportunity to log about 1,000 miles in past four months. While the local mass transit system in highly efficient where I spend most of my time, I do at times envy some people’s ability to take off and drive extended distances.

Bighorn | 2020年1月17日

No argument, though I’m partial to empiric results since it is more applicable on the road. I’ve long since stopped deriving and referencing these numbers other than in helping people past their misapprehensions. The numbers are more disparate on the 85—292 vs 278.

MV | 2020年1月18日

@Bighorn, It would be easier for everyone if Tesla were to show energy stored in the battery in KW on the dash. You buy a car with 100KW battery. If the max storage goes down to 80kw that’s a problem. It means either some cells have gone bad or are storing less (common Li-ion issue). It is an attribute of the car on which the price is determined so it has to be maintained within a specified range. It’s like buying an ICE with 20 gallon gas tank but overtime you can only fill it to 15 gallons or a car with 5 seats but you can only use 4 seats after a while. I wonder if there is an app to know how much energy is stored in KW ? Thx.

Bighorn | 2020年1月18日

@MV
The car measures kWhs consumed ( to the tenths in my S), so it’s an easy extrapolation. Tesla has moved away from that for all the confusion and consternation.

Bighorn | 2020年1月18日

Also, the rated range is a precise conversion of kWhs to rated miles using a fixed rate constant. That’s the figure people know and want—miles. KWh is an abstraction to almost everybody.

Sailfast | 2020年1月18日

@ BH. Are you saying that miles to empty is or is not reflective of your speed and interior climate settings?

Bighorn | 2020年1月18日

@Sailfast
Miles to empty on the little green fuel bar is a fixed efficiency ratio applied to how many kWhs are left in the battery. So if you had 10 kWh in the tank, your fuel gauge would read 36 miles and would not reflect your previous driving conditions or auxiliary draws. Your projected range (on the Energy screen) would be different, based on those factors over the previous 5/15/30 miles. If you'd averaged 350 Wh/m over the chosen distance, the projected range would only be 29 miles.

dunnman99 | 2020年1月20日

Thank you to all who responded, great help and links.

Any idea how to get a suggestion actual “heard” by Tesla? Like the threshold to recalculate charging destination or ability to set an amount required to arrive?

dunnman99 | 2020年1月20日

Thank you to all who responded, great help and links.

Any idea how to get a suggestion actual “heard” by Tesla? Like the threshold to recalculate charging destination or ability to set an amount required to arrive?

Bighorn | 2020年1月20日

Twitter or adding it to one of the several curated lists of suggestions, though those seem to have faded away after a few years.

Sondavid | 2020年1月20日

I did have a very uncharacteristic close encounter yesterday. Chicago area had our first cold snap, my first with Sir Charge, 2015 S90D with 52,000 miles. I got too close to the edge, left to go home with the SuperCharger -4% out. Now, the car routes me to the interstate, but I know the surface roads, and it was hypermile time! It was 25 mph for about the last 8 miles with the heat off, and I pulled into the Merrillville SC at zero the last 1.5 miles.
Ideally, I have seen 220 wh/mile average, as high as over 500, and yes obviously that affects the miles of range shown. I would say, just seat of pants, 1 to 1 at 277 is about right. Basically, it was foolish to leave in 2 degrees F for a 30 mile round trip with 60 miles of range showing.

Sondavid | 2020年1月20日

I did have a very uncharacteristic close encounter yesterday. Chicago area had our first cold snap, my first with Sir Charge, 2015 S90D with 52,000 miles. I got too close to the edge, left to go home with the SuperCharger -4% out. Now, the car routes me to the interstate, but I know the surface roads, and it was hypermile time! It was 25 mph for about the last 8 miles with the heat off, and I pulled into the Merrillville SC at zero the last 1.5 miles.
Ideally, I have seen 220 wh/mile average, as high as over 500, and yes obviously that affects the miles of range shown. I would say, just seat of pants, 1 to 1 at 277 is about right. Basically, it was foolish to leave in 2 degrees F for a 30 mile round trip with 60 miles of range showing.