Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

[DrChaos]

Thanks for this. Does this refer to charging before a trip or leaving a car sitting? In other words, if I charge to 80% before a road trip, or when I'm going to be out running errands all day, will that quicken my degradation?

The rule is pretty simple, more degradation rate above 55% (about 2x) than below 55%. This is calendar aging and depends on time. All 24 hours count, driving, charging, sitting. Yes the time spent above 55% will degrade it more (especially in the heat another major factor), but the details of the charging cycle don't matter too much for this. This motivates the idea to charge late rather than early, so that the time spent sitting (majority of time) is at a lower charge level. It's time prorated so a small amount of time over 55% means a smaller contribution to degradation.

I charge higher than 55% occasionally when I know I'll make a longer trip, and don't worry about it. Maybe 20 days per year at most.

 

[Owner4523]

The rule is pretty simple, more degradation rate above 55% (about 2x) than below 55%. This is calendar aging and depends on time. All 24 hours count, driving, charging, sitting. Yes the time spent above 55% will degrade it more (especially in the heat another major factor), but the details of the charging cycle don't matter too much for this. This motivates the idea to charge late rather than early, so that the time spent sitting (majority of time) is at a lower charge level. It's time prorated so a small amount of time over 55% means a smaller contribution to degradation.

I charge higher than 55% occasionally when I know I'll make a longer trip, and don't worry about it. Maybe 20 days per year at most.

Thanks. I think most Tesla drivers charge their cars to 80-100% and their batteries are fine. I wonder how much of a difference all of this adds up to over time. I wonder if the benefits of micromanaging the battery makes only a very small difference? Based on what you are saying above, every time you charge the battery to 65% and drive the car, you are doubling the amount of degradation? Plenty of people drive their cars with 80-100% car all the time as well as Super Charge all the time and I believe many experience what looks like very similar amounts of degradation to people who do tons of micromanaging.

 

[DrChaos]

Thanks. I think most Tesla drivers charge their cars to 80-100% and their batteries are fine. I wonder how much of a difference all of this adds up to over time. I wonder if the benefits of micromanaging the battery makes only a very small difference? Based on what you are saying above, every time you charge the battery to 65% and drive the car, you are doubling the amount of degradation?

Only for the amount of time above 55%. If it is perpetually above 55% the calendar degradation will be 2x the calendar degradation of below 55%. If you charge to 65% late, and then drive it down, it will less than 24 hrs above 55%. It's not about maximum SOC per day, but continuous time average.

Plenty of people drive their cars with 80-100% car all the time as well as Super Charge all the time and I believe many experience what looks like very similar amounts of degradation to people who do tons of micromanaging.

There's been posts of people here (including me) who find it otherwise. And most people's idea of 'micromanaging' is not scientifically optimal. The importance of low SOC and importance of calendar aging over cyclic is not commonly known.

You need to believe the peer reviewed science of experiments in controlled conditions, and recognize that range estimation in any single car has its uncertainties in the short run. The batteries in the cars aren't some new exotic thing, we know how they work. The proprietary additives and processing generally add a bit of energy and a bit of longevity to a basic battery but otherwise the physical principles are the same, and so is the behavior w.r.t. calendar aging. The testers even buy commercially available batteries.

 

[Owner4523]

Only for the amount of time above 55%. If it is perpetually above 55% the calendar degradation will be 2x the calendar degradation of below 55%. If you charge to 65% late, and then drive it down, it will less than 24 hrs above 55%. It's not about maximum SOC per day, but continuous time average.


There's been posts of people here (including me) who find it otherwise. And most people's idea of 'micromanaging' is not scientifically optimal. The importance of low SOC and importance of calendar aging over cyclic is not commonly known.

You need to believe the peer reviewed science of experiments in controlled conditions, and recognize that range estimation in any single car has its uncertainties in the short run. The batteries in the cars aren't some new exotic thing, we know how they work. The proprietary additives and processing generally add a bit of energy and a bit of longevity to a basic battery but otherwise the physical principles are the same, and so is the behavior w.r.t. calendar aging. The testers even buy commercially available batteries.

But it looks like at the end of the day, everyone's battery eventually degrades by 12-15% no matter how you use it. How much degradation are you actually stopping by keeping the battery under 55%. Also, the car goes to 80% and stays there for 45 minutes as you drive, how much degradation cold the possibly cause? You say it's 2 x more, but how much is the "more" for that short of time? If you had a car that you never charged to 55% you'd think they would see almost no degradation after 5 years. However, there are people I believe who charge to 90-100% and use Super Charging all the time that have low degradation. I'm just trying to wrap my mind around this topic. It seems like at the end of the day everything pretty much gets to the same place.

 

[AlanSubie4Life]

I wonder if the benefits of micromanaging the battery makes only a very small difference?

If I had followed this I probably would have maybe 7% after 5.5 years rather than 10%.

I believe many experience what looks like very similar amounts of degradation to people who do tons of micromanaging.

@AAKEE has formulas that fit. People who have a situation that allows them to follow this method have much better results. It’s particularly impactful for those in warm climates.

There is apparently a possibility that due to reduced stresses it also reduces chances of battery failure but that is hard to prove. @AAKEE could comment.

But it looks like at the end of the day, everyone's battery eventually degrades by 12-15% no matter how you use it. How much degradation are you actually stopping by keeping the battery under 55%.

That is incorrect. Probably can cut these numbers nearly in half. Obviously capacity loss continues, but the point is to have a car with maximum utility while you own it.

Also, the car goes to 80% and stays there for 45 minutes as you drive, how much degradation cold the possibly cause? You say it's 2 x more, but how much is the "more" for that short of time?

It’s 2x the degradation that would be experienced over that time window (which is basically zero for a short window). It’s just time averaged SOC. Most of the time the car is not being driven so that is when it is important to keep SOC low. So: You can charge it to very high SOC as much as you want - it doesn’t matter much as long as it doesn’t sit there.

 

[Owner4523]

If I had followed this I probably would have maybe 7% after 5.5 years rather than 10%.

@AAKEE has formulas that fit. People who have a situation that allows them to follow this method have much better results. It’s particularly impactful for those in warm climates.

There is apparently a possibility that due to reduced stresses it also reduces chances of battery failure but that is hard to prove. @AAKEE could comment.

That is incorrect. Probably can cut these numbers nearly in half. Obviously capacity loss continues, but the point is to have a car with maximum utility while you own it.

It’s 2x the degradation that would be experienced over that time window (which is basically zero for a short window). It’s just time averaged SOC. Most of the time the car is not being driven so that is when it is important to keep SOC low. So: You can charge it to very high SOC as much as you want - it doesn’t matter much as long as it doesn’t sit there.

Thanks, this is helpful information. My car has less than 3,000 miles and I want to start putting some of these tips into play. I assume at under 3,000 miles I haven't made any mistakes that have caused much degradation? Also, I'm glad to see the difference is from 7% to 10% for you. Even 10% isn't horrible.

 

[kpanda17]

2023 MYP 18 Months old, 13K miles, 5.4% loss, hope this is the level off
seems to be inline with statistics graph seen below

 

[Owner4523]

2023 MYP 18 Months old, 13K miles, 5.4% loss, hope this is the level off
seems to be inline with statistics graph seen below
View attachment 1022623

What app / website are you using to track your battery health?

 

[Bouba]

2023 MYP 18 Months old, 13K miles, 5.4% loss, hope this is the level off
seems to be inline with statistics graph seen below
View attachment 1022623

Does the cars battery meter show that loss as well ?...if you remember what range your car did at 100% (or any level) compared to today. There seems to be some controversy over third party apps not knowing the actual original battery capacity of each particular car model

 

[Owner4523]

Does the cars battery meter show that loss as well ?...if you remember what range your car did at 100% (or any level) compared to today. There seems to be some controversy over third party apps not knowing the actual original battery capacity of each particular car model

I have a MY AWD with the 4860 battery and I"m trying to figure out what my original battery capacity is, I have seen different information out there. How do I make sure the apps / websites out there are accurately measuring my batteries degradation?

 

[kpanda17]

Does the cars battery meter show that loss as well ?...if you remember what range your car did at 100% (or any level) compared to today. There seems to be some controversy over third party apps not knowing the actual original battery capacity of each particular car model

no apps, just my analysis, Tesla app or in-car screen, miles at %, multiply up to 100%, showed 214 miles at 76% yields 269 at 100%, orig 100% is 285 miles, now 269 miles is 5.4% loss/degrade

 

[AlanSubie4Life]

Also, I'm glad to see the difference is from 7% to 10% for you

This is just my estimate. No way for me to prove what would have happened.

I assume at under 3,000 miles I haven't made any mistakes that have caused much degradation?

It’s really more about how long you have had the car and how hot it has been and how high the SOC has been. If you had the car for 6 months in Florida at 80% SOC that would have a definite impact with just 3k miles.

2023 Model Y 4680 is about 70kWh, 68kWh degradation threshold, as I recall. These are approximate numbers from memory. Have to get the exact numbers by looking up (searching) on this site. You can determine degradation threshold by calculating the constant and multiplying by the number of EPA rated miles when new.

 

[kpanda17]

be excited, 10 year old Model S with 10 year old battery tech, 1.2M miles, on 4th battery
our new Tesla will do even better

 

[DrChaos]

Thanks, this is helpful information. My car has less than 3,000 miles and I want to start putting some of these tips into play. I assume at under 3,000 miles I haven't made any mistakes that have caused much degradation? Also, I'm glad to see the difference is from 7% to 10% for you. Even 10% isn't horrible.

Sure. Set charge limit to 52%. Set off-peak charging, end charging early in the morning. That's it. It has impacted my life exactly 0 times.

I have 3.9% degradation after 20 months (extrapolating from miles & state of charge estimate in car). I have seen none obviously apparent in 6 months, though underneath it's happening slowly. There will be some losses after the hot part of the summer (Late July/Aug/Sept/Oct in SoCal).

Degradation goes as sqrt(time) according to research papers so limiting the early life degradation is very valuable. So at 5 years old (60 months) 3.9% * sqrt(3) = 6.75%, and going very slowly.

 

[kpanda17]

Sure. Set charge limit to 52%. Set off-peak charging, end charging early in the morning. That's it. It has impacted my life exactly 0 times.

I have 3.9% degradation after 20 months (extrapolating from miles & state of charge estimate in car). I have seen none obviously apparent in 6 months, though underneath it's happening slowly. There will be some losses after the hot part of the summer (Late July/Aug/Sept/Oct in SoCal).

Degradation goes as sqrt(time) according to research papers so limiting the early life degradation is very valuable. So at 5 years old (60 months) 3.9% * sqrt(3) = 6.75%, and going very slowly.

dont forget to balance the pack with a 95% charge once a month or every other month

1. Let the battery fall below 10%
2. Leave it there for at least an hour
3. Charge the battery to 100%

 

[Owner4523]

dont forget to balance the pack with a 95% charge once a month or every other month

1. Let the battery fall below 10%
2. Leave it there for at least an hour
3. Charge the battery to 100%

@AAKEE - what are your thoughts on this?

 

[AlanSubie4Life]

@AAKEE - what are your thoughts on this?

It’s unnecessary. Just charge to 100% when you need it.

@AAKEE has commented before on this many times:


Cell Balancing- What's the benefit? Best Way Without Battery Stress?

 

[nicksp]

But it looks like at the end of the day, everyone's battery eventually degrades by 12-15% no matter how you use it. How much degradation are you actually stopping by keeping the battery under 55%. Also, the car goes to 80% and stays there for 45 minutes as you drive, how much degradation cold the possibly cause? You say it's 2 x more, but how much is the "more" for that short of time? If you had a car that you never charged to 55% you'd think they would see almost no degradation after 5 years. However, there are people I believe who charge to 90-100% and use Super Charging all the time that have low degradation. I'm just trying to wrap my mind around this topic. It seems like at the end of the day everything pretty much gets to the same place.

I agree. Just charge up to whatever your needs are and just drive the damn car.

 

[Bouba]

no apps, just my analysis, Tesla app or in-car screen, miles at %, multiply up to 100%, showed 214 miles at 76% yields 269 at 100%, orig 100% is 285 miles, now 269 miles is 5.4% loss/degrade

That’s probably only a little high for just 20 months old (my Long Range, using the same method of calculations shows about a 3.6% loss over 29 months)....I have never tried a rebalancing campaign, I was saving it for a dramatic loss but you should think about it. Also 285 miles at 100% seems quite low for a new car

 

[AlanSubie4Life]

I agree. Just charge up to whatever your needs are and just drive the damn car.

This is exactly right of course! But no more than needed, with ample margin. This will put many owners below 55% the vast majority of the time.