What should my ideal charge percentage be?

[koorosh]

Daily charging with destination chargers to keep it around 90.

 

[gavine]

I've now had my (well used) 2014 85 for a year. I have been charging to 80% and recently bumped to 82%(ish). Because I got my car from a dealer, I have no information on the PO and his charging habits. I often do 120 miles in a day...

Just turned 117K miles and a full cpacity charge (I've only done it once) took me over 260 miles estimated range. The car is only supercharged. Usually in the late afternoon/evening. No other charging. I'm getting from this thread that I should bump down my 'ceiling' on charging to around 50%.

This is especially pertinent to me since my 8-year battery/drivetrain warranty just expired.

Advice/comments welcomed.

Since you only supercharge, a ceiling SOC of 50% would mean that a lot of your charging will be at quite a high speed which is not great for the battery. If I were only supercharging, I would try and not go below 50% very often so that the charging speed is a little slower and thus easier on the battery.

 

[Dave EV]

Since you only supercharge, a ceiling SOC of 50% would mean that a lot of your charging will be at quite a high speed which is not great for the battery. If I were only supercharging, I would try and not go below 50% very often so that the charging speed is a little slower and thus easier on the battery.

I don't think you can state this as fact without any actual data to back it up.

Yes, Supercharging is fastest below 50% SOC, but the battery is able to handle higher currents at lower states of charge. Tesla limits current based on a number of factors, presumably the risk of long term capacity loss is one of those factors.

But if you wanted the best of both worlds, just go find an urban charger and charge to 50%. Then you keep your SOC low and you limit peak charge rates. For sure, charging at 75 kW up to 50% is easier on the battery than charging at 75% above 50%.

 

[gavine]

I don't think you can state this as fact without any actual data to back it up.

Yes, Supercharging is fastest below 50% SOC, but the battery is able to handle higher currents at lower states of charge. Tesla limits current based on a number of factors, presumably the risk of long term capacity loss is one of those factors.

But if you wanted the best of both worlds, just go find an urban charger and charge to 50%. Then you keep your SOC low and you limit peak charge rates. For sure, charging at 75 kW up to 50% is easier on the battery than charging at 75% above 50%.

I don't have hard data, although it might be out there....but, from what I've learned (mostly on this forum), it's better for battery health to charge more slowly than quickly. So I stand by my opinion that, if it were me, I would try not to charge at the fastest rates very often, especially not every time I charge.

I like your idea of using urban Superchargers. Those are underrated in my opinion and great for charging stops where you're having a meal or shopping. V3 chargers are too fast for that and you have to worry about idle fees.

 

[gavine]

I realize laptops don't have liquid cooled batteries and sophisticated battery management like Tesla, but I had a mobile workstation for about 5 years. It ran very hot when in use. This was before I understood battery health techniques. The laptop was plugged-in 24/7 and was used Monday through Friday every week. It sat at 100% charge continuously.. After the 5 years, I tested the battery and it lost about 85% of it's capacity. In hindsight, I'm actually surprised that it still had that much left under the circumstances. My current laptop is now about 5 years old. I cycle the battery daily and never leave it over 90% any any period of time. I even make sure it's around 50% over the weekend when not being used. I basically follow the battery health guidelines discussed here and the battery still runs for about the same as when it was new (no noticeable degradation).

As a follow-up to this, I just discovered that my laptop has a BIOS setting to limit the charge to 80% so now I can keep it plugged in and it will not go-over 80%. It's an HP Elitebook. I'm glad to see that manufacturers are recognizing battery health measures and giving users this option.

 

[MorrisonHiker]

I don't have hard data, although it might be out there....but, from what I've learned (mostly on this forum), it's better for battery health to charge more slowly than quickly. So I stand by my opinion that, if it were me, I would try not to charge at the fastest rates very often, especially not every time I charge.

I like your idea of using urban Superchargers. Those are underrated in my opinion and great for charging stops where you're having a meal or shopping. V3 chargers are too fast for that and you have to worry about idle fees.

Urban Superchargers are pretty rare around here. We'd have to drive nearly 200 miles to reach the closest one. They must not be that much cheaper than v3 Superchargers since Tesla really hasn't installed many of the urban Superchargers since v3 came out.

 

[Jayy178]

Is it better to charge less often but up to a higher % (say 80%), or better to charge to 50% and more cycles? I had always thought that there were limited charging cycles so charging every few days or so was better than daily, but this thread infers the opposite with SOC being more important

 

[DayTrippin]

Is it better to charge less often but up to a higher % (say 80%), or better to charge to 50% and more cycles? I had always thought that there were limited charging cycles so charging every few days or so was better than daily, but this thread infers the opposite with SOC being more important

One of the key things is DoD; depth of discharge. It is better to do more frequent, "smaller" cycles than bigger, less frequent ones. It is less stress on the battery. Keeping your average state of charge lower is better, but obviously not zero. I shoot for 50% average state of charge. Some good reading on Battery University Homepage.

 

[gavine]

Is it better to charge less often but up to a higher % (say 80%), or better to charge to 50% and more cycles? I had always thought that there were limited charging cycles so charging every few days or so was better than daily, but this thread infers the opposite with SOC being more important

I agree with what @DayTrippin said.....shallow cycles are better. What I wanted to add is that one "cycle" is 100% to 0% and back to 100%. If you go from, let's say 20% to 70% (a 50% discharge cycle), that basically counts as half of a charge cycle. Therefore, a 25% DoD is a quarter of a cycle and so on. If every time you charged the car was counted as a cycle, then regen-alone would use-up all of the cycles very quickly.

 

[Maarten]

Very interesting article about charging habits, supercharging, etc.

What Does Mr. Data Have to Say About Tesla Battery

Tesla battery is an important and expensive part of the car. Naturally, owners are very interested in knowing more about how to preserve…

maadotaa.medium.com

Tl;dr: We do not have to be very preoccupied with the best charging strategy with respect to degradation.

Note: also a nice read at the end about three taps on your IPhone in order to get something specific on the screen.

 

[DayTrippin]

I read through the article. One concern in general is some of the 3's shown there are showing significant degradation even with low miles. Actually a lot of them are showing significant degredation.

Some key thing that would have been helpful is know what environment the cars being pulled from are. For example the operating temps the cars are typically seeing. Apparently a LOT of people follow Elon's advice and charge to 90%.

A lot of what is analyzed goes against the generally accepted tenets of battery care. Even Tesla tells you not to repeatedly charge to 100%. Extensive supercharger use has shown battery degradation elsewhere but not showing up here.

I'd like to see a broader section of models, broken down by model (in case of some unique result) and all lumped together.

 

[FlatSix911]

Very interesting article about charging habits, supercharging, etc.

What Does Mr. Data Have to Say About Tesla Battery

Tesla battery is an important and expensive part of the car. Naturally, owners are very interested in knowing more about how to preserve…

maadotaa.medium.com

Tl;dr: We do not have to be very preoccupied with the best charging strategy with respect to degradation.
Note: also a nice read at the end about three taps on your IPhone in order to get something specific on the screen.

Great article on charging by a data scientist... thanks for sharing.

I also highly recommend his app for real-time data monitoring.

Tesla App | Stats for Tesla

Get statistics for you Tesla that you can use. Find out your driving efficiency. Send addresses from your phone to your Tesla. Export the stats to you computer.

www.maadotaa.com

 

[ucmndd]

Very interesting article about charging habits, supercharging, etc.

What Does Mr. Data Have to Say About Tesla Battery

Tesla battery is an important and expensive part of the car. Naturally, owners are very interested in knowing more about how to preserve…

maadotaa.medium.com

Tl;dr: We do not have to be very preoccupied with the best charging strategy with respect to degradation.

Note: also a nice read at the end about three taps on your IPhone in order to get something specific on the screen.

Nice article. Goes to show that most all of the hocus pocus and anecdotes about how to maintain battery health on this forum are just that, anecdotes with no data to back them up. Battery degradation seems predominantly calendar based and luck of the draw.

I’m approaching 150,000 miles in my Model S. HOT climate in interior California. Almost always charged daily to 90%, hundreds of supercharging sessions, easily a hundred or more 100% charges. Degradation? 12%, holding almost completely steady for the past 2.5 years.

Countless people with the exact same or worse degradation as me at far less mileage, including the fanatics doing all sorts of goofy stuff like never charging above 50%, rarely if ever supercharging, never even dreaming of charging to 100%, etc etc etc.

Just drive.

 

[zoomer0056]

Nice article. Goes to show that most all of the hocus pocus and anecdotes about how to maintain battery health on this forum are just that, anecdotes with no data to back them up. Battery degradation seems predominantly calendar based and luck of the draw.

I’m approaching 150,000 miles in my Model S. HOT climate in interior California. Almost always charged daily to 90%, hundreds of supercharging sessions, easily a hundred or more 100% charges. Degradation? 12%, holding almost completely steady for the past 2.5 years.

Countless people with the exact same or worse degradation as me at far less mileage, including the fanatics doing all sorts of goofy stuff like never charging above 50%, rarely if ever supercharging, never even dreaming of charging to 100%, etc etc etc.

Just drive.

Looks like you've got an extraordinary battery, great! What year is your MS? On average how low does battery % go daily?

 

[ucmndd]

Looks like you've got an extraordinary battery, great! What year is your MS? On average how low does battery % go daily?

Late 2016 S75.

Pre-pandemic I did a 120 mile round trip 5x/week, typical battery duty cycle was 90%-30%.

I drive a lot less now, make the same trip 1-2x/week, although I still use the car for plenty of moderate distance road trips, mostly within CA.

 

[FlatSix911]

Nice article. Goes to show that most all of the hocus pocus and anecdotes about how to maintain battery health on this forum are just that, anecdotes with no data to back them up. Battery degradation seems predominantly calendar based and luck of the draw.
I’m approaching 150,000 miles in my Model S. HOT climate in interior California. Almost always charged daily to 90%, hundreds of supercharging sessions, easily a hundred or more 100% charges. Degradation? 12%, holding almost completely steady for the past 2.5 years.
Countless people with the exact same or worse degradation as me at far less mileage, including the fanatics doing all sorts of goofy stuff like never charging above 50%, rarely if ever supercharging, never even dreaming of charging to 100%, etc etc etc.
Just drive.

Just drive - I agree completely. Here are his summary findings based on the data from tens of thousands of Stats app users.

Conclusion
I find these results somewhat comforting and liberating because they tell me that:

1. I don’t have to be worried about the battery degradation because it is relatively small and does not go down drastically as the car ages.
2. I don’t have to be super careful about how I charge my car. Lower SoC and higher charge limit do not seem to affect battery degradation in a significant way
3. Supercharging does not cause severe battery degradation

 

[gavine]

Nice article. Goes to show that most all of the hocus pocus and anecdotes about how to maintain battery health on this forum are just that, anecdotes with no data to back them up. Battery degradation seems predominantly calendar based and luck of the draw.

I’m approaching 150,000 miles in my Model S. HOT climate in interior California. Almost always charged daily to 90%, hundreds of supercharging sessions, easily a hundred or more 100% charges. Degradation? 12%, holding almost completely steady for the past 2.5 years.

Countless people with the exact same or worse degradation as me at far less mileage, including the fanatics doing all sorts of goofy stuff like never charging above 50%, rarely if ever supercharging, never even dreaming of charging to 100%, etc etc etc.

Just drive.

How do you know that your 12% degradation is accurate? Perhaps all of those 100% charges have balanced the pack and reset the algorithm to display your mileage more-correctly than those who didn't. It doesn't necessarily mean they have more degradation. It's just what your guess-o-meter shows vs. theirs.

 

[zoomer0056]

How do you know that your 12% degradation is accurate? Perhaps all of those 100% charges have balanced the pack and reset the algorithm to display your mileage more-correctly

Does an unbalanced pack show more or less than actual range? I'm wondering about that.

 

[ucmndd]

How do you know that your 12% degradation is accurate? Perhaps all of those 100% charges have balanced the pack and reset the algorithm to display your mileage more-correctly than those who didn't. It doesn't necessarily mean they have more degradation. It's just what your guess-o-meter shows vs. theirs.

If a battery degrades in the forest and there’s nobody around to panic and make sure it doesn’t sit too long at 100%, does it even make a sound?

It’s inconsequential in either case. I’ve read all sorts of hocus pocus threads in the Model 3 forum about “recovering range” and resetting pack algorithms and all that other sorcery. Success with any of those methods appears to be completely random. So again, we’re back to the observation that the primary factors affecting degradation are time and luck.

Just drive.

 

[DayTrippin]

Just drive - I agree completely. Here are his summary findings based on the data from tens of thousands of Stats app users.

Conclusion
I find these results somewhat comforting and liberating because they tell me that:

1. I don’t have to be worried about the battery degradation because it is relatively small and does not go down drastically as the car ages.
2. I don’t have to be super careful about how I charge my car. Lower SoC and higher charge limit do not seem to affect battery degradation in a significant way
3. Supercharging does not cause severe battery degradation

My concern is some of the findings go counter to a lot of well documented info regarding lithium ion batteries. The info comes from uncontrolled environments so not really sure what all is at play here.

I would encourage reading through battery university. A good reference page on prolonging battery life is here.

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com