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Ideal charge limit for new MS 85 (100 miles per day usage)
- Thread starter theatwar99
- Start date
ThosEM
Space Weatherman
I've tried 90% and lower SOC values on the strength of arguments made here. But then I realized that I've never seen any data or evidence in support of the claim that lower SOC is "healthier". So the two points made above seem definitive to me. If you ever have to make a warranty claim concerning your battery, which position do you want to be in: having followed Tesla recommendations, or having followed hearsay/forum recommendations?
Case in point: when closing your frunk, did you ever fail to place both hands on the extreme corners of the hood as directed in the owner's guide? Well, then, Tesla is not responsible for your frunk "crease."
No question about it the advice is highly variable, including advice from Tesla Service Center people. Why?
since widespread use of li-ion technologies in automotive applications is less than a decade old there really is not established history of apples-apples comparisons. Even exact chemistries, manufacturing technology and process, charging protocols, protective circuitry and battery management systems have been constantly evolving. There are at least five distinct 85 KWH battery packs for Tesla, reflecting changes in most, if not all, of those factors.
Some experienced Model S drivers (one person I met with 65,000 miles and essentially new performance is an example, as is Cottonwood) say use 100% anytime and run close to Zero too, if you dare, because the Tesla BMS will protect you from harm.
Other experienced people say that li-ion, regardless of specific chemistry or BMS, are happiest in the middle SOC levels so treat your battery packs accordingly. Tesla encourages that idea by describing 20% to 90% SOC as the preferred daily range level going outside that range only "when necessary" or "for long trips" depending on which advice you read.
I am am in the latter camp. I have never gone below 20%, not once. I often have arrived at 20%. I do not go near empty in ICE, either. I do go to 100% if I am a leg with expected bad weather, low temperatures, substantial altitude change or undependable charging access at my destination.
I think we all know the precise SOC algorithms themselves change and that the most precise methods of establishing algorithms accuracy require full charge following by prompt nearly full discharge them recharging. Such a practice is itself somewhat abusive and yields pretty small incremental benefit, so why bother?
As several people say, we need not agonise about this. Our cars are built to handle normal use. Probably better to avoid everyday charging to above 90% or everyday discharge below 20%. Probably better to plug it in whenever we can, because Teska recommend that. Anyway, dice and enjoy!
since widespread use of li-ion technologies in automotive applications is less than a decade old there really is not established history of apples-apples comparisons. Even exact chemistries, manufacturing technology and process, charging protocols, protective circuitry and battery management systems have been constantly evolving. There are at least five distinct 85 KWH battery packs for Tesla, reflecting changes in most, if not all, of those factors.
Some experienced Model S drivers (one person I met with 65,000 miles and essentially new performance is an example, as is Cottonwood) say use 100% anytime and run close to Zero too, if you dare, because the Tesla BMS will protect you from harm.
Other experienced people say that li-ion, regardless of specific chemistry or BMS, are happiest in the middle SOC levels so treat your battery packs accordingly. Tesla encourages that idea by describing 20% to 90% SOC as the preferred daily range level going outside that range only "when necessary" or "for long trips" depending on which advice you read.
I am am in the latter camp. I have never gone below 20%, not once. I often have arrived at 20%. I do not go near empty in ICE, either. I do go to 100% if I am a leg with expected bad weather, low temperatures, substantial altitude change or undependable charging access at my destination.
I think we all know the precise SOC algorithms themselves change and that the most precise methods of establishing algorithms accuracy require full charge following by prompt nearly full discharge them recharging. Such a practice is itself somewhat abusive and yields pretty small incremental benefit, so why bother?
As several people say, we need not agonise about this. Our cars are built to handle normal use. Probably better to avoid everyday charging to above 90% or everyday discharge below 20%. Probably better to plug it in whenever we can, because Teska recommend that. Anyway, dice and enjoy!
I can't speak for everyone that bought a car this year but for me and my friends the 90% recommendation has been a consistent message from Tesla.
taurusking
Member
That's quite interesting because its been more than a year I took delivery of my car and they never came up with 90% recommendation.
Looks like we need a poll from new buyers to see what kind of instructions they are getting from Tesla.
Nevertheless I have been charging to 90%
cantdecide
Member
My story is that at 2 years and 40k miles my range had dropped from 265 to 260 on my P85. Typically I charged to 90% but to 100% once per week (where I would drive it an hour or two later). Is anyone going to pay less second hand as a result?
A more conservative driving pattern would be unlikely to have improved that even 1 mile. It would probably be more beneficial to the battery to always chose shortest-route instead of shortest-time and save a few percent on the milage.
Life isn't worth wasting on minor 0.01% optimizations like that... Just charge to 90% daily and 100% when needed and take away the stress... And enjoy your car!
A more conservative driving pattern would be unlikely to have improved that even 1 mile. It would probably be more beneficial to the battery to always chose shortest-route instead of shortest-time and save a few percent on the milage.
Life isn't worth wasting on minor 0.01% optimizations like that... Just charge to 90% daily and 100% when needed and take away the stress... And enjoy your car!
BertL
Active Member
Right.
- 90% being used as my "normal" daily charge has been confirmed to me from 4 different physical Tesla employees since delivery on 10/5/2015: during delivery independently by both of my Delivery Specialists, again by my Service Advisor last week as part of my whole 90D reduced range issue discussion, and a month or so ago when I was talking to Tesla Tech Support via the 800 number for a HPWC problem I was having.
- 90% is also what came set as the default in my 6.2 software on my MS upon delivery
- While the current Owner's Manual suggests anything from 50-100% can be set based upon need, as a software and technical support guy my whole career, I take special note that there is a distinct physical and graphical "indent" in 6.2 and 7.0 charging software suggesting 90% is some sort of "sweet spot" or whatever one wants to call it on the UI. IMHO it's something Tesla has specifically chosen to code and provide to all owners... not 70%, 80%, 93%, or some other number that may have been used in the past. I find it hard to believe Tesla did not have specific intent with their decision to implement this design point that helps coach and suggest a good default if you personally don't have a better reason to override it.
Wow. Some of you seem to be unaware of a very important fact.
@msnow, Quote: “I don't see why you just don't follow the advice of Tesla. They are the experts and are accountable.”
@ThosEM, Quote: “If you ever have to make a warranty claim concerning your battery, […] “
@BertL, Quote: “Tesla has also retroactively increased the traction battery warranty to 8 years (longer if mandated by local jurisdiction) since early MS came off the line, and that warranty goes so far as to have almost no exclusions as to what an owner may have done to it beyond physically tampering or damaging it in a wreck.”
All of you seem completely unaware that the warranty text does actually very specifically EXCLUDE degradation of capacity from warranty coverage. So no, they are not “accountable” for this, and even with few other exclusions, this sure is one.
@ThosEM, Quote: “But then I realized that I've never seen any data or evidence in support of the claim that lower SOC is "healthier".”
Then you just haven’t actually read any of the data from battery degradation studies that have been done by the experts. Mid-range state of charge is established as being healthiest.
People seem to be taking a fact: “Tesla sales people recommend 90%.” but are drawing the wrong conclusion from it: “It must be best for the health of the battery.” It is obvious why the sales and PR people tell people to use 90%. If they told people to use 50% because it is best for avoiding degradation, there would be huge wailing and gnashing of teeth about range anxiety and panic, and “why did I spend $$$$$ on this car, when I can’t use more than half the battery and can’t go where I need to?”, etc. etc. etc. They are telling people a higher level because they want people to have more range to use to not be so upset and frustrated about having a Nissan Leaf range at 4X the price.
I seriously can’t get my head around how people here can mentally hold these two ideas in their head simultaneously:
I’m not saying don’t use 90%. I’m just saying it doesn’t make the least bit of sense to say that it’s the ideal level for charging for battery health.
@msnow, Quote: “I don't see why you just don't follow the advice of Tesla. They are the experts and are accountable.”
@ThosEM, Quote: “If you ever have to make a warranty claim concerning your battery, […] “
@BertL, Quote: “Tesla has also retroactively increased the traction battery warranty to 8 years (longer if mandated by local jurisdiction) since early MS came off the line, and that warranty goes so far as to have almost no exclusions as to what an owner may have done to it beyond physically tampering or damaging it in a wreck.”
All of you seem completely unaware that the warranty text does actually very specifically EXCLUDE degradation of capacity from warranty coverage. So no, they are not “accountable” for this, and even with few other exclusions, this sure is one.
@ThosEM, Quote: “But then I realized that I've never seen any data or evidence in support of the claim that lower SOC is "healthier".”
Then you just haven’t actually read any of the data from battery degradation studies that have been done by the experts. Mid-range state of charge is established as being healthiest.
People seem to be taking a fact: “Tesla sales people recommend 90%.” but are drawing the wrong conclusion from it: “It must be best for the health of the battery.” It is obvious why the sales and PR people tell people to use 90%. If they told people to use 50% because it is best for avoiding degradation, there would be huge wailing and gnashing of teeth about range anxiety and panic, and “why did I spend $$$$$ on this car, when I can’t use more than half the battery and can’t go where I need to?”, etc. etc. etc. They are telling people a higher level because they want people to have more range to use to not be so upset and frustrated about having a Nissan Leaf range at 4X the price.
I seriously can’t get my head around how people here can mentally hold these two ideas in their head simultaneously:
- 91% is specifically recommended against and is not OK for daily usage, and is in the “trip zone” on the car, and will give warnings not to use it too much.
- 90%, a difference so small as to be in the measurement noise, is magically the best, most ideal place to charge to and is the best level for the batteries.
I’m not saying don’t use 90%. I’m just saying it doesn’t make the least bit of sense to say that it’s the ideal level for charging for battery health.
The Tobacco Companies all called... they said cigarettes were actually good for you.
The Oil Companies all called... they were all in agreement, global warning is a myth and gasoline is like "butta".
Yep, no "big important company" or industry would put out conflicting or contrary information to actual fact for their own gain. Nope. They know all, so follow their recommendations without thinking or due diligence... they are all knowing, right?
@Rocky_H, the limited battery warranty does cover defects and other things related to the battery but not issues relating to "normal use". I'm not going to get into the legalities or guess as to the definition of "normal" as I'm not a lawyer but to the extent you abuse your battery it is specifically not covered as is "normal" degradation. So they ARE in fact accountable beyond the exclusions!
Regarding who recommended the 90% to me it was my Delivery Specialist, two different Service Advisors and two different Service Technicians. As the manufacturers yes I look at them as the authoritative source for their product. The rest of your argument that charging to 90% is some marketing ploy doesn't make sense to me in addition to being pure speculation.
Regarding who recommended the 90% to me it was my Delivery Specialist, two different Service Advisors and two different Service Technicians. As the manufacturers yes I look at them as the authoritative source for their product. The rest of your argument that charging to 90% is some marketing ploy doesn't make sense to me in addition to being pure speculation.
Soolim
Member
Tesla does not guarantee any battery degradation due to too many factors, hence we are having this armchair discussion on what is best for the battery. Some delivery specialist does not know any better than the more knowledgeable members of this forum (not me).:tongue: Two things I know that Tesla does not recommend:
1) charge to 100% and leave it there
2) drain the battery to 0 remaining km.
Other than that, charge to 50% or 90% that works for your daily drive is a personal preference (i.e. whatever makes you happy).:wink:
Happy New Year to everyone! :biggrin:
1) charge to 100% and leave it there
2) drain the battery to 0 remaining km.
Other than that, charge to 50% or 90% that works for your daily drive is a personal preference (i.e. whatever makes you happy).:wink:
Happy New Year to everyone! :biggrin:
I agree with you but for the record Tesla service people are telling customers this not just some random DS.
I also know there are several very knowledgable people on this forum including you [emoji6] but no two of you agree on this.
Happy New Year!!
Mike
No one is saying that 90% is the ideal level for battery health. We're saying it's the ideal level for maximizing range without significantly harming the battery, or having to think about how much range you have when the unexpected comes up. That's not to say 91% would, but you have to draw the line somewhere and it's a nice round number. Remember the original firmware set 93% charge for daily use. I don't know what battery degradation studies you are referring to, there are none with Tesla batteries that show concerning degradation at 90% usual charge. There may be a statistically significant drop in range compared to 70 or 80% but it's not likely to be a meaningful difference. If someone is that concerned about a loss of an additional 2 or 3 miles of range after X years then they aren't giving themselves enough of a charging buffer on trips.
I think that is reasonable advice, and is essentially what Tesla says (service and sales employees parroting their customer relations training line of "90%" notwithstanding).
I do not believe there is a single "ideal" state of charge, or even a very narrow range of "ideal". 50 to 90% is likely all the same in terms of long term battery health. The fact is we really don't know for sure. Tesla likely has good data for 3 year old batteries (but no proven data for 10 year old batteries because there aren't any) but they aren't going to reveal the numbers. I seriously doubt that their internal date supports the view that 90% is "ideal".
I would charge to 90%, timed to complete when you leave in the morning. This way your car will sit at about 70% for 8 hours at work and somewhere around 50% for 10-12 hours before charging starts again. This minimizes the time at a higher SOC and maximizes your driving range, should you need it. Also, it seems that charging to 90% regularly maintains the range the car thinks it has. Also, I would do a range charge every couple of months to allow the pack to rebalance.
Rebalancing is triggered at 93% according to WK57 who's done a lot of research on this. Once triggered, it balances at any SOC. Based on this research, it shouldn't be necessary to do the full 100% charge to balance the battery.
Previously, I've charged to 80% and 100% when needed. I have the timer set for 02;30 so most of the day it sits at less than 80%. This winter I started 90% charge (with the same timer), but will go back to 80% when the weather warms up. A typical day is 50-60 miles.
Cottonwood
Roadster#433, Model S#S37
Most days for me are 30-60 miles. I charge to 80%, normally.
If I know that I will have a 100 mile or more day, I charge to 90%. Before starting on a long, multi-charge trip, I set the timer to start charging from 90% to 100% at 2 hours before I leave; that way, the full 100% finishes, then I drive the 100% charge off soon after.. If I will leave the car for more than a week, I set the charge at 50-60%, leave the car plugged in, and let the vampire suck the battery down towards that level.
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