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Charge to 50% weekdays, 95% Friday & Saturday

holmgang

Active Member
Sep 9, 2019
1,365
1,505
eu
And then there is basically no information that backs up exactly how much total mileage will be saved by only charging to 50%. Are you charging to 50% to get an extra 10 miles on a battery that's going to last 300,000 miles?

How much will you shorten your life by smoking 1 cigarette, 2 cigarette, 3 cigarette?

Just because the effect is not perfectly quantified, does not mean the effect is not known - that smoking is detrimental to health. Same way , it's known in Li-Ion battery chemistry that high state of charge is relatively more stressful than mid state of charge (along with temp, current, etc)

What it's worth to each person is a personal matter. I do 80% because it's convenient to me. And I'll puff on a cigarette once in a while, too.
 

ewoodrick

Well-Known Member
Apr 13, 2018
5,285
4,282
Buford, GA
How much will you shorten your life by smoking 1 cigarette, 2 cigarette, 3 cigarette?

Just because the effect is not perfectly quantified, does not mean the effect is not known - that smoking is detrimental to health. Same way , it's known in Li-Ion battery chemistry that high state of charge is relatively more stressful than mid state of charge (along with temp, current, etc)

What it's worth to each person is a personal matter. I do 80% because it's convenient to me. And I'll puff on a cigarette once in a while, too.

I'm not looking for perfect quantification. I'm looking for ballparks, or even a city sized quantification.
Tesla uses a battery that's explicitly designed for long life and the specific utilization in an EV. With auto laws and the warranty that Tesla provides, that requires MTBF to be significantly long. This isn't the same cell that you would use in a cellphone or a laptop.

People sometimes use "experts" to backup their point, but in all of those situations, it's an oranges vs apples correlation. You can't really say that charging a battery to 100% is bad, because I don't think that we really know what 100% is. Tesla has done a LOT OF WORK to extend the battery life, and folks are recommendations based on raw cells.

Elon has indicated that the Model 3 is trending for 300,000 mile life. I'd assume that means an average. So would charging to 100% decrease the range to 250,000 miles? In which case, I don't care.

The closest evidence that we have to date are Model 3s that are passing 100,000 miles with no apparent degradation and the older Model S and X batteries that are going string at over 300,000 miles per battery with multiple Supercharging stops daily.

Should we be going from empirical evidence on these batteries or what?
 

PianoAl

Active Member
Dec 15, 2019
1,032
696
Far Northern California
I suggest setting the limit to 85%, and have your computer remind you every Friday and Saturday night to set it to 100% if you plan a trip. My computer reminds me to charge the laptop on Friday nights:

Screen Shot 2020-02-19 at 7.13.33 AM.jpg
 

Kirby64

Member
Jun 28, 2018
485
515
Austin, TX
I'm not looking for perfect quantification. I'm looking for ballparks, or even a city sized quantification.
Tesla uses a battery that's explicitly designed for long life and the specific utilization in an EV. With auto laws and the warranty that Tesla provides, that requires MTBF to be significantly long. This isn't the same cell that you would use in a cellphone or a laptop.

People sometimes use "experts" to backup their point, but in all of those situations, it's an oranges vs apples correlation. You can't really say that charging a battery to 100% is bad, because I don't think that we really know what 100% is. Tesla has done a LOT OF WORK to extend the battery life, and folks are recommendations based on raw cells.

Elon has indicated that the Model 3 is trending for 300,000 mile life. I'd assume that means an average. So would charging to 100% decrease the range to 250,000 miles? In which case, I don't care.

The closest evidence that we have to date are Model 3s that are passing 100,000 miles with no apparent degradation and the older Model S and X batteries that are going string at over 300,000 miles per battery with multiple Supercharging stops daily.

Should we be going from empirical evidence on these batteries or what?

Elon also loves to make ridiculously overstated, albeit technically true statements. Your assumption of the 'average' being 300k miles is probably misguided.

Also, we do roughly know what 100% is on a battery. It's like 4.16V per cell. Which equates to 96s @ 400V. 4.15V on a cell level isn't great for batteries to rest at. There's a reason Tesla recommends you don't charge above 90%.

Obviously some people have had luck with 100k mile degradation, but it's also very unclear how mileage reported by the BMS correlates to the health of the battery. Is it completely 1:1? Is it highly non-linear? (e.g. would mileage reported stay steady for awhile then fall off a cliff quickly?)

Also, it's not apples to oranges here. Lithium ion batteries are lithium ion batteries. What applies at the raw cell level, broadly also applies at the pack level. Sure, some things aren't exactly the same, but the general rule applies: lower resting voltage = longer battery life. Period.
 

woodguyatl

Member
Oct 3, 2018
446
379
GA
And what "need" is it fulfilling? Aside from just providing fodder to make you worry more? Does your car drive better with the info? Does it get better range? Does it go faster?

Or does it just feed the range anxiety?

People drive ICE all the time without worrying about a mile by mile efficiency of the engine. And yes, they do vary like an EV does. But no one cares. If the car can get you from point A to B, what does it really matter?

On a 311 mile car, if my max charge starts being around 250 miles, then I know it's time to talk to Tesla.

Otherwise, all of the details that the apps are given are based on guesses. That's what the car is feeding the app, guesses. There is no such thing as Max Charge. For example, a LR Model 3 can go 600+ miles. Is 600 miles the "Max Charge" then?

For me, at least, Stats has done a few things. It alerts me when my daughter left the door open by accident. It lets me know my software version relative to the fleet. A few other features are nice as well.
 

electrongeek

Metrology Fanboy
Nov 1, 2019
69
74
Maine
Come on guys, don't bring battery chemistry science into this. It might scare some people. Best just to drink the Kool Aid and assume that what Uncle Elon tweets is the Gospel, and you don't need to think any more. Reminds me of how some people take another famous tweeter. BTW, I do concede that Elon is a genius, and I love my TM3.
 
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