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SDH

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FWIW, I spoke to a friend not long ago who has a 2014 Tesla Model S (100 I think). Because he's got free supercharging for life he literally never gave 'battery management' a second thought. Let it run to 1%, charged it loads at superchargers from 90%-100% etc. etc.

I asked him about the battery life and range and he said that it has barely moved. Yes, there's been the odd OTA update that's juiced a bit more range but on the whole he reckons he getting pretty much the same as in 2014, maybe a couple % less.

Just an anecdote.
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FWIW, I spoke to a friend not long ago who has a 2014 Tesla Model S (100 I think). Because he's got free supercharging for life he literally never gave 'battery management' a second thought. Let it run to 1%, charged it loads at superchargers from 90%-100% etc. etc.

I asked him about the battery life and range and he said that it has barely moved. Yes, there's been the odd OTA update that's juiced a bit more range but on the whole he reckons he getting pretty much the same as in 2014, maybe a couple % less.

Just an anecdote.
interestingly I had a uber driver not that long ago with a 2016 model S that said he charges to 100% at home every night and he's lost less than 5% after 100k+ miles. That sounded amazing to me just cause my phone battery charging to 100% after only 3 years has lost a fifth of its charging capacity.. Maybe these car batteries are built to handle the stress of fully charging and/or the temperature management systems help relieve the stress on the batteries.
 

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Just FYI...

Below is my Recurrent report for Jan 2023. You can see that I've lost roughly 6% in 4.5 yrs but not expected to lose much more over the next 3 yrs. Also I have my charge setting to 90% SOC. The plot on the lower right shows how often its above the 80% range.

My sense is that Tesla does a great job managing battery life. Don't know if Tesla results are applicable to every EV battery. In other words, we need to see track record of each EV maker to have a sense of general trend (or specific trend i.e., Rivian).

I know some people plug in everyday regardless of SOC and/or keep it plugged in as "shore power" - I do not. It usually gets plugged in as needed for my next use.

Rivian R1T R1S Charging to Optimize Battery Life - What's Your Strategy? 1674583730576
 

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It is strange to me that plugging in every day to ~80% is better than plugging in every other day to 100%. My daily commute is 120+ miles so unless I charge to 100% I'm charging every night...
 

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Just FYI...

Below is my Recurrent report for Jan 2023. You can see that I've lost roughly 6% in 4.5 yrs but not expected to lose much more over the next 3 yrs. Also I have my charge setting to 90% SOC. The plot on the lower right shows how often its above the 80% range.

My sense is that Tesla does a great job managing battery life. Don't know if Tesla results are applicable to every EV battery. In other words, we need to see track record of each EV maker to have a sense of general trend (or specific trend i.e., Rivian).

I know some people plug in everyday regardless of SOC and/or keep it plugged in as "shore power" - I do not. It usually gets plugged in as needed for my next use.

1674583730576.png
Do you know how do they do the calculation? As far I know Tesla rolled out some software updates that increased the range even on the same existing battery, so range comparison might not be accurate one. For testing a regular lithium battery the technique is to use a shunt to get current+voltage reading and run down from 100% to 0% to measure the capacity. I wish the vehicle itself shows something like this like iPhone shows for battery health.
 

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It is strange to me that plugging in every day to ~80% is better than plugging in every other day to 100%. My daily commute is 120+ miles so unless I charge to 100% I'm charging every night...
The issue is that the battery chemistry used in these vehicles doesn't like being charged to 100% and it degrades your battery health, long-term.
 

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It is strange to me that plugging in every day to ~80% is better than plugging in every other day to 100%. My daily commute is 120+ miles so unless I charge to 100% I'm charging every night...
It's just how lithium ion battery works. I read some paper where they basically claim keeping the battery discharge cycle between 20-80% reduce capacity loss by half. Even iPhone these days don't charge to 100% at night until about the time to wake up to reduce degradation.

There are lot of other factors that can degrade capacity faster. Heat, very high/low SoC, fast charge/discharge all has some impact.

Though this is not related to vehicle battery but it touches the subject of heat and charging battery to full capacity
 

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I tend to keep my battery between 40%-70%. Smarter people than me have recommended the 70% for daily, and I don't need more than that for daily driving. I do charge if I am at home and near 40%. Maybe I should use more of the lower end of the battery, but with where I live, I feel more comfortable having at least 40% when at home. If I am on a trip, I identify chargers ahead of time and use them when convenient. If I know I will be driving a lot the next day (>125 miles), I will probably charge to 85%, and top off to 100% in the morning if I think I may need it (or feel more comfortable with it). I also charge to 85% for my last day of the week at work, it takes about 15% to get home, so I will be around 70% when I get home, and that little bit of extra charge will save me around $3, almost half of a beer at the bar. Since getting my R1T, I have charged to 100% twice (needed/wanted full battery for family visits during Christmas with temps in the teens). I have done DCFC four times, twice before I was hooked up at home, and twice during those cold Christmas visits. If there is a forecast for severe weather, I may charge to 85% or even 100% , if I think there is a chance for my house to lose power.
 

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Most days I drive less than 50 miles and usually less than 35. When I get home I'm usually somewhere between 50-60% (it's been really cold so I'm getting worse range than normal.) I have it set to 70% and plug in every night when I get home. Do the same with my wife's MY although hers is set to 80%.

If I know I'm going to be driving down to SLC during the day I'll try to charge to 85% the night before. That 3000' elevation gain on the way back up is a killer on range.
 

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FWIW, I spoke to a friend not long ago who has a 2014 Tesla Model S (100 I think). Because he's got free supercharging for life he literally never gave 'battery management' a second thought. Let it run to 1%, charged it loads at superchargers from 90%-100% etc. etc.

I asked him about the battery life and range and he said that it has barely moved. Yes, there's been the odd OTA update that's juiced a bit more range but on the whole he reckons he getting pretty much the same as in 2014, maybe a couple % less.

Just an anecdote.
I had a 2014 Model S 85. Same experience. I plugged it in every night and charged it to 80%. Sometimes to 100%. Never had an issue and it only lost a few miles of estimated range over 8 years. I monitored my usage with the TeslaFi app and saw that a lot of other Teslas had the same experience. Was surprised by the lack of degradation in the batteries over time.
 

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WIth the Model S, I ready ABC (always be charging) was best because the BMS would always read the voltage from the packs. In the Model 3, they cut costs and the BMS doesn't read the voltages as often. With our Model 3, we found we'd 'lose' range with the ABC method and read a number of others had similar experiences. Now we drive it down to 20% and charge to 80%, more like a normal car. And over the course of a few months the range re-appeared. Essentially, range dropped from 295 to 270. Now it's back.

I'm not sure how often Rivian samples the voltages to get a good estimate of the voltage and, therefore, the capacity. ABC probably makes more sense with the Rivian because it's their first car and they want to make sure they have as much data for the BMS as possible, so they'll take a lot more data while it's charging.
 
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My current strategy is not to have a battery until somewhere between June and Sept, pretty sure if I don't have one it will last longer :CWL:


That being said does anyone have data or a number at which you should start seeing degradation? e.g if you have 5k miles on it, you'll see nothing, but you'll see it starting at 25k or 50k or whatever miles. A lot of people are saying in 5 years they'll have something different and don't care. So are we talking 60k miles? less than 100k?

And has anyone actually reached that point. Does anyone have data for the Rivian where they have 100-0'd it many times to see the charging (aside from Rivian of course, I hope they have it).
 

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I believe the best strategy is no strategy.

Where you can simplify it down to a few basic rules.

Don't leave it at 100% for a long time. A few hours is fine during an overnight charge before a road trip. Just don't do something like leaving on vacation with the vehicle plugged in with the limit set to 100%.

Try not to leave it with very little battery power.

Try not to fast charge it excessively.

Mostly try to leave it between 20% and 80%.
 

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Almost universally the best way to reduce calendar aging is to maintain the lowest possible charge level, although the benefits in trying to 'maximize' this life diminish as you go lower in charge level (Chemistries are obviously going to vary somewhat but here's an actual paper on it.) Low SOC doesn't hurt batteries unless you're trying to pull a bunch of power from a nearly dead cell, which the car already will limit. Obviously leaving it close to dead makes the car useless (and the car drains when idle) so it's not ideal here. You're also not going to do any noticeable damage charging it full overnight or leaving it for a day or two, you just don't want to maintain it there long term. If your alternative to a full charge is fast charging somewhere - you should be taking the full charge every time, not only is it easier and cheaper, it's less likely to get you stranded, and it's generally better for the battery too.

For cycling efficiency, short cycles are best. 100-0 is worse than 100-50 is worse than 70-50, but again considering the way we use cars compared to phones or something (where you may burn a full charge in a day) you're not likely to really have to think about it. If you just plug it in every time to 70 that requires no thinking and will generally be fine. Calendar aging on something like a car is typically more noticeable than cycling aging just because very rarely will people drain them every day.

IMO the real reason to not leave the car plugged in is the energy wasting behavior of the car. Forget about the battery cells - if you leave it plugged in it's constantly trying to keep the battery conditioned for charging, which in the cold costs a lot of power. If you aren't topping the charge constantly it doesn't need to heat because storing the batteries cold doesn't cause any harm, and above -20F is generally beneficial. Charging them in that state however would cause damage and you would need to heat them to 40F or higher. The battery is 1700lbs, heating it in cold ambients often takes more than 1500W as we've seen from people trying to cold charge on 120V and losing power. I don't know about you but I don't leave space heaters running in the garage overnight, so I'm loathe to spend the same electricity on a car doing practically the same thing.
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