# State of Charge Predictions and SuperCharging Times



## NR4P (Jul 14, 2018)

For the past year, I have done monthly 900 mile weekend Round Trips. I know the SC's I need to use etc.
But for the past two trips, the SOC prediction upon arrival at the next SC has been way off.

Example, prediction is 2 hour + drive, starting at 90% SOC and arrival at 26% SOC.
Actual arrival SOC is 18%.

Another example, starting at 90%, prediction is 47% to arrive home but arrived at 41%.

A year ago, these calculations were almost always right on the money or variance was 2 points.
A few days ago an 18% prediction ended up at 10% upon arrival.

Also, SC times are now always 5 mins longer than predicted (yes taking A/B sharing into account assuming no sharing)

Now I did get new tires 3K miles ago, so the first trip I might have expected this. But after 2K miles and now on the second trip, the variance is growing, not declining.
Yes the wheel size is correct.

In 2019, Tesla allegedly added other variances to the calculations such as temperature. BTW, these are Florida miles so low temp in not a factor.

Interested in other experiences? Learnings? Insight?


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## Feathermerchant (Sep 17, 2018)

Are the new tires the same as the old? ie same treadwear rating?


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## JWardell (May 9, 2016)

It's getting colder.


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## garsh (Apr 4, 2016)

JWardell said:


> It's getting colder.


Still pretty warm in Florida though.

@NR4P, I assume you're not driving through rain, right?
Have you checked your tire pressures?
What make/model/size tire did you get this time?


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## NR4P (Jul 14, 2018)

garsh said:


> Still pretty warm in Florida though.
> 
> @NR4P, I assume you're not driving through rain, right?
> Have you checked your tire pressures?
> What make/model/size tire did you get this time?


I did get new tires before the first run, 3K miles ago. 19" Conti Comfort Plus. So the wh/mile did increase on the first trip but on the first 900 mile RT weekend the SOC was off only 3-4%. Tire break in period. No rain on the first half, rain on the second half.

In the past week, on the first half of the trip, temp was 87 degs, no rain.
On the return, temp was 80 no rain.
Wh/mile have settled back after the first 2K miles.

Tire pressures cold 42 as specified, and when running at highway speeds they go as high as 44, occasional 45. But back to 42 when parked.


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## Feathermerchant (Sep 17, 2018)

Just to be clear for others, the recommended air pressure for any vehicle is while the tire is 'cold' that is at ambient temperature or sitting idle for 8 hours or so.
Never let air out of a tire because its pressure has increased above the 'cold' recommendation.

FWIW I run 45-46 in my Model 3 performance and our new Model Y.


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