Odd trend

SoFlaModel3

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#1
I have noticed an odd trend the last few days. I set my charge limit to ~85% and haven’t touched it. That would be 263.5 miles of range.

A few weeks ago that would show charging complete with 266 miles of range. It dropped to 265 for a days. Then a few days at 262 miles. Now tonight charging is complete at 257 miles.

Odd, right?
 

tencate

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#2
It's averaging? ;) Seriously, I never actually look at the limit. I set it higher when I go on a trip and dial it down for everyday use. I plug Max in every night and as long as I'm showing over 200 or so in the morning, I'm good to go. I'll try paying closer attention next few days.
 

SoFlaModel3

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#3
It's averaging? ;) Seriously, I never actually look at the limit. I set it higher when I go on a trip and dial it down for everyday use. I plug Max in every night and as long as I'm showing over 200 or so in the morning, I'm good to go. I'll try paying closer attention next few days.
I wouldn’t say I watch it that closely, but can tell for sure that I am trending down on an 85% charge range.
 

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#5
Estimating the amount of energy contained in a battery is still part voo-doo as much as science. It’s not as simple as dipping a stick in a tank. There will always be variances in the resulting guess, and the trend is still too short-term to worry about. Tesla batteries do have a bit of “break-in” period too, and if you look at the old Model S charts for capacity over mileage, you see that the measured capacity will drop a few percentage fairly early in ownership (first 10K miles or so), but then stabilize and barely budge for many 10s of thousands of miles after that. I’ll see if I can track down that chart somewhere.
 

John

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#6
With a service like Teslafi you can collect data all the time and look at trends. Keeps a record of all of that stuff. Also shows you when other people are getting new firmware updates, which is my favorite feature.
 
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#8
It's because of temperature most likely. It sounds like the BMS is doing a calculation of of what 85% is based on OCV (open circuit voltage) within the temp range your battery is at. At higher temps your battery can store more energy. At lower temps it can store less. So 85% @ 10C is different from 85% @ 20C.

So it sounds like they are using an average of what 85% equals in Ah, regardless of temp. It is also possible there is a temp diff from the time you charged to the time you drive which causes that mile difference.

Battery capacities vary wildly based on temperature, rate of charge/discharge and what the charge/discharge profiles look like. There is a lot of work being done to make the correlation between miles and battery capacity, but right now it's all estimation really.
 

MelindaV

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#9
Estimating the amount of energy contained in a battery is still part voo-doo as much as science. It’s not as simple as dipping a stick in a tank. There will always be variances in the resulting guess, and the trend is still too short-term to worry about. Tesla batteries do have a bit of “break-in” period too, and if you look at the old Model S charts for capacity over mileage, you see that the measured capacity will drop a few percentage fairly early in ownership (first 10K miles or so), but then stabilize and barely budge for many 10s of thousands of miles after that. I’ll see if I can track down that chart somewhere.
for that matter, my gasoline car can have a ¼ tank swing over a few miles drive depending on the speed because it thinks it is smarter than a person looking and seeing the gauge is at a specific spot and in stop and go traffic that takes more fuel than going at 60mph. (kinda sounds like I'm insulted the car patronizes me, huh?)
 

Dogwhistle

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#10
I wish there was an option to turn off both the SOC gauge and the Miles remaining gauge beside the battery icon, so that we just have the basic battery icon on the screen. The hyper-specificity of this data is causing a lot of stress, it would be much more relaxing to just treat it like an old-fashioned fuel gauge. You get below roughly 1/4 of a “tank”, fill-er-up! I don’t want to feel like I have to constantly monitoring my fuel flow rate or remaining range, that’s the beauty of an LR Tesla, you shouldn’t have to!
 

garsh

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#13
And with old analog gauges, I could have a ¼ tank swing depending on if the car was pointing uphill or downhill. :p

for that matter, my gasoline car can have a ¼ tank swing over a few miles drive depending on the speed because it thinks it is smarter than a person looking and seeing the gauge is at a specific spot and in stop and go traffic that takes more fuel than going at 60mph. (kinda sounds like I'm insulted the car patronizes me, huh?)
 

Enginerd

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#14
I wish there was an option to turn off both the SOC gauge and the Miles remaining gauge
OK for you... if that were an option, I wouldn't use it. I do a lot of highway driving with a stable of ICE cars (for now). I find that the only time I have range anxiety is when I don't have a car that displays estimated distance to empty. I want to spend as little of my life in gas stations as possible, and maximizing range (within reason) is the only way to do it. I anticipate that I'll feel the same way when my 3 comes.
 

CrunchyLumpia

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#15
On my one week old Model 3 my 90% charge was going to 280 but now the last few times have been 272/273. Should I be worried?

Luckily, there is a mobile service around town that will take a look and make an assessment.
 

goto10

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#16
On my one week old Model 3 my 90% charge was going to 280 but now the last few times have been 272/273. Should I be worried?
I might trying to cycle the battery once - hold off on charging it until it's pretty low and then charge back to 95-100%. There's a myth going around that this will "balance" the pack but I think it may actually allow the car to better calibrate it's state of charge estimate.
 

teslarob

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#18
This is similar to ICE vehicles that don't show you the exact same miles to empty every time you filled it up. A difference of a few miles is nothing to worry about. As suggested, discharging then fully charging should help "reset" the values back to normal.
 
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goto10

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#19
"Cycling" generally means to use and fill most/all of the capacity. So down to 5-10% and then back up to 95-100%. Don't let it sit around at 95-100% for very long though. It's not good for the battery to be kept full for a long time which is why Tesla (and everyone else) recommend not charging above 90% unless you need to go on a long drive. Right now I'm charging to 100% for a road trip and plan to hit the road as soon as the charge is complete.
 
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#20
I just set to percentage and I don’t worry. Navi tells me what percent at destination and with return. If it’s enough to get there or back depending on what I’m doing I don’t care too much. I don’t see the range either so no fussing over a few miles. I know it’s about 10% to work and 10% back so if it’s significantly different I’ll know there’s a problem.