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What should my ideal charge percentage be?

Fiver

Active Member
Apr 10, 2015
1,853
1,544
Utah
Well if all that were true (not saying it is not) why not put it in the manual. If their batteries lasted longer then they would make more money. Wondering if you did 50% and pack went bad if you voided warranty by NOT following manual operation instructions? You know the huge amount of data they collect.

M
Because the manual is written for the lowest common denominator. People that don’t dive deeper into how lithium batteries work. There really isn’t any significant harm leaving your car plugged in at 90%, and that setting allows for decent range. Can you imagine if Tesla said "here’s your big battery car, but for best results long term only use 60% of that battery"? The media would have a field day.

So yea, if you want to leave the car plugged in and set to 90% go for it, but anyone who knows anything about lithium ion batteries knows that storing them at about 50% charge is better for longevity. It won’t change the fact that batteries lose capacity as they age over time, but slows down that process a little. If you don’t need the range, keep it in the middle of the pack. When you do need the range, charge it up to whatever you need. That’s part of why, even though I leave the car set to 50% I still plug in. I can always remotely increase the charge percentage should I know I need the extra range.

How often do you completely out of the blue and with no warning, need to drive 240 miles?
 

Rsilb3

New Member
Jul 25, 2020
2
0
Colorado
Given the introduction of the "slider" I would like Tesla to give a number (percentage charge) that is optimal for the life of the pack. If you never (or almost never) need the full, or even standard charge range; what is the best level to charge to on a daily basis? Most driving days for me are less than 30 miles. What's my number? I'm certain it wouldn't totally end speculation. If Tesla engineers came up with a number for this scenario it would end any speculation for me.
Been told optimal charge is 80 to 90 %. Above that is reserved for topping off directly before going on road trip.
 

Truthman

Member
Aug 3, 2020
27
4
Sacramento
Given the introduction of the "slider" I would like Tesla to give a number (percentage charge) that is optimal for the life of the pack. If you never (or almost never) need the full, or even standard charge range; what is the best level to charge to on a daily basis? Most driving days for me are less than 30 miles. What's my number? I'm certain it wouldn't totally end speculation. If Tesla engineers came up with a number for this scenario it would end any speculation for me.
Hi, I’m a former Tesla employee and it is recommended to charge daily; you pick—between 80% to 90%. Use a regular charging regiment and don’t drop below 20% or it will thriwb
Given the introduction of the "slider" I would like Tesla to give a number (percentage charge) that is optimal for the life of the pack. If you never (or almost never) need the full, or even standard charge range; what is the best level to charge to on a daily basis? Most driving days for me are less than 30 miles. What's my number? I'm certain it wouldn't totally end speculation. If Tesla engineers came up with a number for this scenario it would end any speculation for me.
 
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Truthman

Member
Aug 3, 2020
27
4
Sacramento
Hi, I’m a former Tesla employee and it is recommended to charge daily; you pick—between 80% to 90%. Use a regular charging regiment and don’t drop below 20% or it will thriwb
They won’t come up with a number. They have to protect themselves. That’s why there’s ambiguity and no official documentation for customers.
 

Truthman

Member
Aug 3, 2020
27
4
Sacramento
They won’t come up with a number. They have to protect themselves. That’s why there’s ambiguity and no official documentation for customers.
It is recommended to charge between 80% and 90%. Don’t drop below 20%. The optimal would be 40% to 80 or 90. The more consistent you are with your driving and charging habits the more accurate the range estimate will be.
 
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Klaus

Member
Apr 20, 2013
513
62
It is recommended to charge between 80% and 90%. Don’t drop below 20%. The optimal would be 40% to 80 or 90. The more consistent you are with your driving and charging habits the more accurate the range estimate will be.
Well, there is the range estimate which is generated by an algorithm of which we only know a few pieces. And then there is the real battery capacity which gets affected by different factors. People have figured out in the past that charging to less than 90% may result in accumulating range estimate errors. There is also the issue of cell balancing which used to occur at 93% charge or higher, in 85 kWh times. Lack of balancing will at least temporarily result in reduced range/capacity. Charging to higher than 90% will diminish real capacity more quickly, so there are trade offs. We’ve watched Tesla adjust those trade offs over time, with preconditioning, decreased and increased max charge power and fast charge power “gate”. Recall the instantaneous range estimate changes after certain software updates. Aside from a few experts in the Tesla battery labs, some of the executives in charge and probably a few external experts no one really knows the parameters of those trade offs in enough detail to make definitive statements, Tesla employee or not. And Tesla the company will never tell us because they want to avoid the liability. All my opinion and accumulated tidbits from memory, take it as such.
 
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Truthman

Member
Aug 3, 2020
27
4
Sacramento
Some Tesla insiders will tell you 80% while others will say 90%. You’ll get varying opinions from engineers, technicians, etc...That’s what makes it so frustrating. One engineering document states one percentage while another lists a different one. Yes, this is absolutely true. Lol. But the only two numbers that come up are 80 or 90.
 

Fiver

Active Member
Apr 10, 2015
1,853
1,544
Utah
Also, at this point there are so many different flavors of battery packs that what is best for one might not be for another. I think each pack size has had at least 4-6 versions during their production runs. Honestly beyond the broad strokes (charge for what you need, keep it in the middle of the pack, avoid going above 90, and below 15%) there really aren't any hard numbers, as everyone is driving on different cells.
 
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arnis

Member
Apr 13, 2015
920
596
Estonia
And the reason WHY Tesla will never state a number...because EPA.
Nissan did specify "recommended" SOC and look what happened.
EPA takes BATTERY SAVER MODE (80%) in consideration when calculating official range.
This is why Nissan disabled 80% mode a year later... only in US. ONLY..in US. And it's still missing. Idi0ts :confused::mad:
 

Candleflame

Active Member
Mar 9, 2015
2,507
1,144
QLD, Australia
Hi, I’m a former Tesla employee and it is recommended to charge daily; you pick—between 80% to 90%. Use a regular charging regiment and don’t drop below 20% or it will thriwb

I dont think Tesla will ever share their battery care secrets. Im sure they have detailed data on charging behaviours and impact of range.

Afaik the 90% number comes from Model S community data where people noticed that the people with the least degradation are the ones who just plug in and set their range to 90% every day. The assumption is that its not true degradation for cars which charge to 80% but just an estimation error which can take months to correct on an 80% car.

Out of interest, why do you think that dropping below 20% is bad for the car? All evidence we have on lithium ion batteries is that cycling 0 - 70% is WAY healthier than 30 - 100% or even 20 - 90% for battery longevity.
 
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Jughead135

Member
Feb 19, 2020
195
83
Georgia
Afaik the 90% number comes from Model S community data where people noticed that the people with the least degradation are the ones who just plug in and set their range to 90% every day. The assumption is that its not true degradation for cars which charge to 80% but just an estimation error which can take months to correct on an 80% car.

Out of interest, why do you think that dropping below 20% is bad for the car? All evidence we have on lithium ion batteries is that cycling 0 - 70% is WAY healthier than 30 - 100% or even 20 - 90% for battery longevity.


I'm confused. I'd thought that keeping the battery in the mid-range (50%, +/-) was ideal for longer parking periods; and staying relatively low (<~80%) was the way to go for daily driving.

Sounds like you're saying 90% is an ideal target? Does that apply to storage as well? And, if per your last paragraph, going to 70% is "WAY healthier" than 90%.... :confused::confused::confused:

I'm still a Tesla newbie, and I want to do all I can to get as much longevity out of my car. Please help me understand this!!
 

Candleflame

Active Member
Mar 9, 2015
2,507
1,144
QLD, Australia
I confirm. I've cycled my EV between 1-7% and 80% a LOT and I have one of the best battery state in my climate.

i also do lots of long range traveling on either slow DC or just 3 phase, often cycling 70 - 0% or 80% - 0% and until the 0.20 update i had one of the best batteries according to teslafi. I could charge to like 493km until a few weeks ago. The 0.20 update reduced this to 470 km though. havnt done a full charge since then though so who knows...
 

Candleflame

Active Member
Mar 9, 2015
2,507
1,144
QLD, Australia
I'm confused. I'd thought that keeping the battery in the mid-range (50%, +/-) was ideal for longer parking periods; and staying relatively low (<~80%) was the way to go for daily driving.

Sounds like you're saying 90% is an ideal target? Does that apply to storage as well? And, if per your last paragraph, going to 70% is "WAY healthier" than 90%.... :confused::confused::confused:

I'm still a Tesla newbie, and I want to do all I can to get as much longevity out of my car. Please help me understand this!!

we are talking about cycling. for storage probably 60% is the best given that you got a 3% hidden buffer and like 5% visible buffer on the bottom....
 

Electric700

Active Member
May 21, 2013
1,695
358
Florida, United States
I think 10 - 80% is better for the battery than 0 - 80%. Plus, when you go to 0% you leave no room for detours or other issues. Just take a break and grab some food at a Supercharger so you can stay above 9%!

You should be fine with 10 - 85 or 90% too.
 

arnis

Member
Apr 13, 2015
920
596
Estonia
Logistical and emotional issues have nothing to do with battery health. Let's keep them separate.
0% is actually VERY high voltage and is "healthwise" far from zero.
0-80% gives better cycle life. But difference is less than 1% capacity drop per year. So hardly matters.
 

Candleflame

Active Member
Mar 9, 2015
2,507
1,144
QLD, Australia
I think 10 - 80% is better for the battery than 0 - 80%. Plus, when you go to 0% you leave no room for detours or other issues. Just take a break and grab some food at a Supercharger so you can stay above 9%!

You should be fine with 10 - 85 or 90% too.

of course it is. but the question is... is 0 - 70% better than 10-80%?

The commet of staying above 9% is easy but not every country has dense supercharger coverage like the USA. I.e. my nearest supercharger is 1350km away. So the cars see a lot of deep cycling from i.e. 95% to 3%.
 

af88

Member
Sep 28, 2019
199
33
Cali
What is important is to understand is the Voltage of the cell. What Tesla does not do and I know this from experience with the PW is provide cell voltage and BMS data. This is far more important than an arbitrary %, as the 100% is not a true representation of voltage from nominal levels in the PW. I don't know if the same logic is used by Tesla when it comes to car batteries, but this is what is actually far more important to know first before talking about %.

I've had many discussions with Tesla engineers (HW and SW) about this, the reason they don't provide this information is simply to protect Tesla's interest and their claims. It creates a clout of ambiguity, but I also understand why Tesla does this as the masses don't understand how Li cell technology works. Most people buy a new phone every 1-3 years, they certainly don't care about degradation, battery storage, fast charging and how all these factors affect battery life. Same applies to EV's using the same or similar Li chemistry.

In any case, assuming unlike the Tesla PW, the auto batteries and BMS % reporting in the car correlates to max recommended cell voltage, the nominal happy storage % for car battery is as follows below; caveat here is assumed cell voltage and IR, along with what Tesla uses in their algorithm as max charge. Having said that, I have seen a chart of degradation of a M3 LR and after thousands of charge cycles the packs with least amount of degradation was a max charge of 75% and no lower than 65% before being charged which equates to 3.15Vdc/cell to 2.73Vdc/cell for what it's worth.

~4.2Vdc/cell > 100%
~3.6Vdc/cell > 85.71%

In a nutshell, don't ever expect Tesla to be forthcoming with this information. Battery replacement is not cheap on these cars and they will likely replace anything with a hard failure with refurbished pack (confirmed by Tesla support center). Best advice if you want your battery to last is educate yourself on Li cell technology and take care not to abuse the battery. Otherwise expect to treat your car like a cell phone except with a much larger price tag.
 

wayner

Active Member
Oct 29, 2014
3,810
1,385
Toronto
Any idea on what the real world experience is for Model Ss that have been in the field for many years and have had hundreds of charge cycles? Surely we should have a better understanding of how those batteries have degraded over time? I have had my car for 6.5 years and I am nowhere near a pioneer as people have had cars for several years longer and driver WAY more than me as I have only driven 65,000km in my time.
 

gavine

Petrol Head turned EV Enthusiast
Apr 1, 2014
2,569
2,102
Philadelphia, PA
Any idea on what the real world experience is for Model Ss that have been in the field for many years and have had hundreds of charge cycles? Surely we should have a better understanding of how those batteries have degraded over time? I have had my car for 6.5 years and I am nowhere near a pioneer as people have had cars for several years longer and driver WAY more than me as I have only driven 65,000km in my time.

 
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