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Changing Range Remaining

TW14 9LF

2nd EV
Oct 28, 2018
289
256
SoCal
So I haven't been driving my car much since the pandemic allowed me to work at home, in fact, since March, I've only put about 2,000 miles on my Tesla. But, every couple of weeks, I do have to go to the office, which is a 85 mile round trip.

Yesterday I did that drive, and noticed some weird behavior with the "Range Remaining" figure on the screen. And, yes, before a bunch of you go off on "you should have that set to % remaining, then you won't see this" comments, I've tried both ways, and frankly, I like the range remaining more than % remaining. I regularly charge my car at home to 80%, which shows as 250 miles remaining. As I stated earlier, my round trip commute is 85.3 miles. From the car screen, I used 19 kWh of electricity, with an efficiency score of 227 Wh/mi. But, after doing that drive, my range remaining was only 134 miles. So, I drove 85 miles, with a pretty good efficiency score, but I used 116 miles of electricity. Doesn't add up. But, I did have sentry mode on while the car was in the parking garage at work for 11 hours, although only had one alert. So, was puzzled, but didn't think much more about it.

Now, the strange part. Later in the evening, I went out in the garage to plug the car in. I get the notification on my phone that the car had just started charging, with battery at 150 miles. Whoa, where did the 16 miles come from? Did they just appear in my battery? Do I have some kind of wireless charging going on here? A little over 3 hours later, I get the notification that the car had finished charging, this time reporting the battery at 249 miles. So, anybody have any rationale for A) why my range drops so much even though the efficiency score is pretty good, and B) where the 16 miles of range came from?

Background, 2018 LR RWD, 21,000 miles, lifetime efficiency score of 238 Wh/mi, temperature range between 55 and 75, mostly highway driving at 75-80 mph, except for about 15 miles of 20-25 mph stop and go.

Keith
 
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Reactions: Victoria3

Gasaraki

Active Member
Oct 21, 2019
1,668
1,070
Syracuse, NY
Efficiency is calculated just from the power use of your drive train. The battery meter miles remaining is for all energy use so anything on top of driving will drain that "miles remaining" faster. The miles remaining battery meter is never accurate, it will drain faster especially in the winter time. Sentry mode uses energy even if you have no events. The cameras are on and looking all the time. The car doesn't go to sleep.
 

TW14 9LF

2nd EV
Oct 28, 2018
289
256
SoCal
Thanks for the response....yes, understand that. So that explains why I drove 85 miles, but "used" 116 miles of electricity (although, that's a lot of energy to be used to run Sentry mode, using that rate, my battery would go to zero in a week of using Sentry mode). What that doesn't explain is why the car reported 134 miles remaining when I parked it, but reported 150 miles remaining when I plugged it in to recharge.

Must be the funny Elon Math.......

Keith
 

Gasaraki

Active Member
Oct 21, 2019
1,668
1,070
Syracuse, NY
Thanks for the response....yes, understand that. So that explains why I drove 85 miles, but "used" 116 miles of electricity (although, that's a lot of energy to be used to run Sentry mode, using that rate, my battery would go to zero in a week of using Sentry mode). What that doesn't explain is why the car reported 134 miles remaining when I parked it, but reported 150 miles remaining when I plugged it in to recharge.

Must be the funny Elon Math.......

Keith

The only thing I can guess is that the app was wrong. Even though the app said 150 miles, the car would have said something different if you were in front of the screen. I've had a few times where the app said it was 82% but it was 80% in the car.
 

KenC

Active Member
Sep 4, 2018
3,553
3,217
Maine
Yes, I agree with @Gasaraki , your car used miles while parked, primarily due to Sentry.

As for the additional miles, take a screenshot the next time it happens ,but perhaps, there was a lag between the start of charging and when you got the notification, so that when you looked, 16miles had already been added.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,839
9,803
Riverside Co. CA
Thanks for the response....yes, understand that. So that explains why I drove 85 miles, but "used" 116 miles of electricity (although, that's a lot of energy to be used to run Sentry mode, using that rate, my battery would go to zero in a week of using Sentry mode). What that doesn't explain is why the car reported 134 miles remaining when I parked it, but reported 150 miles remaining when I plugged it in to recharge.

Must be the funny Elon Math.......

Keith

Sentry mode uses between 1 to 2 miles an hour of range (so between 24 to 48 miles of range in a 24 hour period). Yes, your car would "go to zero in a week of using sentry mode". 7 days of 24 / 7 sentry mode would be from 168 "miles range" used to 336 "miles range" used.

The range increase thing can be chalked up to the fact that the car is estimating that number, and its estimations changed during its sleep period based on its evaluation of the state of the battery.
 

TW14 9LF

2nd EV
Oct 28, 2018
289
256
SoCal
The only thing I can guess is that the app was wrong. Even though the app said 150 miles, the car would have said something different if you were in front of the screen. I've had a few times where the app said it was 82% but it was 80% in the car.

So, thought of that, should have included it in my original post. When I saw that the mileage was higher on the app, I opened the car door, and the screen came up saying the same thing (150 miles remaining). This was within 90 seconds of plugging in.
 

TW14 9LF

2nd EV
Oct 28, 2018
289
256
SoCal
Sentry mode uses between 1 to 2 miles an hour of range (so between 24 to 48 miles of range in a 24 hour period). Yes, your car would "go to zero in a week of using sentry mode". 7 days of 24 / 7 sentry mode would be from 168 "miles range" used to 336 "miles range" used.

The range increase thing can be chalked up to the fact that the car is estimating that number, and its estimations changed during its sleep period based on its evaluation of the state of the battery.

Surprised that sentry mode uses so much electricity, but that does explain 20 or so miles of difference, as I left the car in the parking garage at my office for about 11 hours. Will have to make sure not to leave sentry mode on the next time I go on a business trip and leave the car parked at the airport. I've done that in the past, and although I noticed the drain was higher than if it wasn't on, I don't remember a 25-50 mile decrease per day.

Regarding the range increase, that was my thought as well. However, I guess I'm surprised that it was >10% adjustment, plus I don't think I've ever seen that difference before. But, to be honest, guess I've never really looked at it that close either. Will pay more attention next time. The car had been sitting without being driven for two weeks. I had woken it up a couple of times during that period, once to get something out of the trunk, and on Sunday when I pulled it out of the garage to wash off the dust and fire ash. So, the long period of sitting may have been throwing the estimates off as well.

Keith
 

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