Add range overnight? Without charging?

msjulie

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#1
My daily routine is to charge the car at work in the am; this means the car goes home and back, about 30-ish miles between charges. It charges each day to 270-271 miles. Usually by day's end, it's used a mile of range and some nights it loses a few miles too.

Except not today. This morning come out to see the car has 264 miles of indicated range which would suggest I drove 15-ish miles at 1/2 cost and zero loss overnight. Never happened before...

The behavior continued back to work - I have 33 miles since last charge but at 1/2 the 'cost'. I didn't do anything different; did some calibration magic happen? Anyone else see this? For sure will be watching in the coming days to see how it continues, or not, to be so frugal.

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Pescakl1

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#2
Is the weather getting warmer? Is your past consumption getting better? Did you moved your range from rated to typical?

Are those numbers estimate like on other cars (EV and ICE) and could vary depending on external conditions (temperature and past experiences)?

In my ICE BMW I have sometimes "more fuel" after some driving...
 

BigBri

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#4
Might just be your usage patterns with the car. I'm unsure with Tesla but I own a Leaf and the estimate can jump around a bit. It can be a bit of a challenge to accurately calculate the range when you're charging from 60-80% all the time. With my Leaf its suggested to take it pretty low every so often to keep the calculations primed and accurate. If you watch Bjorn on YouTube he's run into problems a few times where his Model X should have 10KM left but it dies beforehand and hes needed a tow to a charger.
 

garsh

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#5
Remember, batteries use chemistry to create electricity. Chemical reactions are dependent on temperature, among other things. Mileage estimates are made using guesses about how much electricity the battery can generate at that time and how efficiently you will drive. So don't read too much into the mileage estimates.
 

John

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#6
Yes. I'm not sure people fully appreciate the thought that goes into providing an estimate of remaining battery life.
It's a little like standing next to your piggy bank and answering the question "How much longer will the money in that bank last?"
Totally depends on how you spend it next, and you can't be sure someone didn't take some out while you weren't looking, even if you tried very diligently to count everything going in and going out. So every now and then you need to dump it all out and count it back in to be sure.

Add to that various psychological effects that an experienced company learns to build in based on typical human behavior. Most notably: better to under-estimate remaining mileage than over-estimate it (up to a point). Also might make sense to be conservative as long as you can to mask battery degradation over time. In other words, tell people 310 miles even if it's 320 when new, so that after a few years you can continue to say "310" when full.

My buddy who owns a Bolt says he "never" gets 238 miles from a full charge, and never has. When I told him Model 3 was rated for 310 miles, he said, "So how many do you actually get?" I replied, "Well, driving like I have been lately, my average usage is 247 Wh/mile, so 300-something."

The most accurate measure of your battery range would be to start with a full charge, run it all the way down and measure the miles, then measure how many kWh it took to fill it up. And even then, that will just be the range for how you drove during that time, and the weather, and the change in elevation, and the amount of stop and go, and the load in the car, and the pressure in the tires. You get the picture. Complicated.
 
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garsh

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#7
...then measure how many kWh it took to fill it up.
And that will vary a lot with temperature. A cold battery can't can't convert as much energy into chemical storage.
 

msjulie

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#8
Ok here's the update. When I got in this am to charge, it only needed 40mins or so (about 1/2 normal charge time) to reach the typical 270. Based on the 'magic' readings that made sense.

Reality returned this afternoon, the car had lost 16 miles of range during the short day - coincidently the exact magic amount it gave me for free this am. It reminded me that on Tuesday, with low to mid 70s temps, the regen limit indicator had come on every other stop light for a stretch of road. Together these 2 events seemed more unusual than 1 or the other alone.

Called Tesla, they are downloading and analyzing the logs as they agreed it seems unusual behavior for a car otherwise predictable to a fault (in my short 2800+ miles of ownership).

Keep in mind I've had other EV's including this, the Roadster, etc so I understand the imperfection of battery capacity measuring and the impacts of temperature on battery chemistry etc. This was/is an unusual event even given all that - eager to see if the logs provide anything at all..
 

John

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#9
Ok here's the update. When I got in this am to charge, it only needed 40mins or so (about 1/2 normal charge time) to reach the typical 270. Based on the 'magic' readings that made sense.

Reality returned this afternoon, the car had lost 16 miles of range during the short day - coincidently the exact magic amount it gave me for free this am. It reminded me that on Tuesday, with low to mid 70s temps, the regen limit indicator had come on every other stop light for a stretch of road. Together these 2 events seemed more unusual than 1 or the other alone.

Called Tesla, they are downloading and analyzing the logs as they agreed it seems unusual behavior for a car otherwise predictable to a fault (in my short 2800+ miles of ownership).

Keep in mind I've had other EV's including this, the Roadster, etc so I understand the imperfection of battery capacity measuring and the impacts of temperature on battery chemistry etc. This was/is an unusual event even given all that - eager to see if the logs provide anything at all..
Keep in mind that because of this behavior, this is more likely to be a software glitch than a hardware one. In other words, your battery's not jumping around, the number they show you is. If that's any consolation.
 

msjulie

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#10
more likely to be a software glitch
Yeah most likely, want to see if they find any sensor out of bounds too - either way, if it is a persistent behavior, it will limit how much the car can charge - if it thinks it has more than it does. Right now the number is small but.. it's going from San Jose to Las Vegas in a few weeks and it can't be not charging properly! :)
 

John

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#11
Yeah most likely, want to see if they find any sensor out of bounds too - either way, if it is a persistent behavior, it will limit how much the car can charge - if it thinks it has more than it does. Right now the number is small but.. it's going from San Jose to Las Vegas in a few weeks and it can't be not charging properly! :)
Be interesting to hear what Tesla says after checking the logs...
Please share.