SOC, minimal bottom and above top SOC range iddling time

[Nikon201068]

Hello TMCers, I like to know how long can the car sit iddling at bottom SOC (let's say around 20% or less) before I should charge it back up to at least 50% or more. Also, how long can the car sit iddling at above SOC (let's say 90% or more) before it should be driven to bring the SOC to more ideal range? Is it few hours or a day or more? Thank you kindly for your inputs.
Edit: I mainly like to know in regard to battery degradation how long or how soon you should charge or drive off to minimize battery degradation.

 

[Snerruc]

Hello TMCers, I like to know how long can the car sit iddling at bottom SOC (let's say around 20% or less) before I should charge it back up to at least 50% or more. Also, how long can the car sit iddling at above SOC (let's say 90% or more) before it should be driven to bring the SOC to more ideal range? Is it few hours or a day or more? Thank you kindly for your inputs.

Car can sit indefinitely at 90%. Same for 10%, unless you leave something turned on.

 

[Nikon201068]

Car can sit indefinitely at 90%. Same for 10%, unless you leave something turned on.

Thank you for your response. I realize the car can sit idefinitely at those levels. Perhaps I was not clear with my questions. I mainly wanted to know in regard to battery degradation how long or how soon you should charge or drive off to minimize battery degradation.

 

[Nikon201068]

I charge my cars mostly at home. My off peak hours are from 12 am to 3 pm. I like to charge during off-peak if I can. For example, I have commute round trip about 100+ miles so by the time I get home around 6pm the car could be at 15-30% SOC. Can I wait until my off-peak hours after 12am the next day to charge back up or I should plug in asap? Thank you

 

[ucmndd]

Lower states of charge are better for battery longevity as a general rule. There is zero harm in letting the car sit at low states of charge.

 

[Nikon201068]

Lower states of charge are better for battery longevity as a general rule. There is zero harm in letting the car sit at low states of charge.

Thank you

 

[SageBrush]

Can I wait until my off-peak hours after 12am the next day to charge back up

No problem letting the car sit at 15 - 20% SoC

Is your off-peak really only 3 hours ?
---
As for SoC > 80%, less time sitting at high SoC will result in less degradation over time. This is particularly true as pack temperature increases. I shoot for less than an hour, but anything less than a couple of hours is probably fine on a daily basis.

 

[Nikon201068]

No problem letting the car sit at 15 - 20% SoC

Is your off-peak really only 3 hours ?
---
As for SoC > 80%, less time sitting at high SoC will result in less degradation over time. This is particularly true as pack temperature increases. I shoot for less than an hour, but anything less than a couple of hours is probably fine on a daily basis.

Thank you much.
btw, my off-peak is from 12am to 3pm. So it's about 15 hours.

 

[SageBrush]

btw, my off-peak is from 12am to 3pm. So it's about 15 hours.

That makes more sense
You can set your car to finish charging about the time you leave for work, and not worry about charging to 90%

 

[BitJam]

Lower states of charge are better for battery longevity as a general rule. There is zero harm in letting the car sit at low states of charge.

I disagree. Low states of charge are just as bad as (or worse than) high states of charge. If you are storing your car for a long time then it's best to set it to 50% SoC. One source for this information is Kyle Conner from Out of Spec Motoring.

Even Tesla says this.

​

Model 3 Owner's Manual | Tesla

Learn about your vehicle’s battery and battery best practices.

www.tesla.com

Never allow the Battery to fully discharge.​

​

Discharging the Battery to 0% may result in damage to vehicle components. To protect against a complete discharge, Model 3 enters a low-power consumption mode when the displayed charge level drops to approximately 0%. In this mode, the Battery stops supporting the onboard electronics and auxiliary low voltage battery. Once this low-power consumption mode is active, immediately plug in Model 3 to prevent a jump-start and low voltage battery replacement.​

​

OTOH both Tesla and Kyle recommend topping the car up to 100% right before leaving for a road trip.

 

[beatle]

Letting the battery discharge fully to 0% is not the same as having a low SoC. Since you can't set the desired SoC to less than 50% anyway, this is pretty much moot, but that's not what the OP was asking.

WRT the OP's question, how long you can let the car sit from 20% before needing to charge depends on your phantom drain and battery size. Cold (or high) temperatures and use of sentry mode can contribute to more phantom drain. I don't think I would go more than a week without charging the car if my SoC was that low, but you should easily be good for a few days.

 

[AAKEE]

Perhaps I was not clear with my questions. I mainly wanted to know in regard to battery degradation how long or how soon you should charge or drive off to minimize battery degradation.

You will get conflicting answers about this.
The main reason is that there are a lot of forum myths. A lot of people got cought by these myths.

For low SOC = the lower SOC the better, when we are talking degradation. Even down to 0% if we only think about the lithium cells.
If the Hv Battery goes too low it shut down to protect itself, and then the 12V battery is mot charged. Most Teslas have a lead scud battery that does not like to be discharged.
So, keeping low SOC but not below 0% displayed (to safeguard the 12V battery) is safe.
This is a calendar aging curve from actual testing. Most teslas have the NCA chemistry, all LR and Performance have in USA.

(This is one chart but the research comes up with the same result each time. This is valid data.)

We can clearly see that low SOC is causing less degradation from time.

High SOC cause more degradation but there is not a big difference between 65-100%, so leaving the car at 90% is “safe”.
It cause more degradation than if below 60% but about the same as most people charge to, 70-80%.

For Cyclic aging, low SOC is better and small cycles is better.
100% is worse but not a very big difference to 80 or 90%.

This chart shows NCA cells cycled to 0 % from 100%, about 90% and about 80%.
Normal driving /charging is at the same rate as the grey lines, sometimes hidden behind the blue line.

100-0% cycles did hold about 625 cycles before they lost 20%.
90-0% cycles did hold for 800 FCE (full cycles equivalent) before they lost 20%
80-0% did hold up 1000 FCE cycles before they lost 20%.

625 cycles is about 250.000 km or 155.000miles
800 cycles is 320.000 km or 200.000 miles
1000 cycles is about 400.000 km 250.000 miles.
As we see, going down to 0% does not kill the battery.
We also see that 100% will not kill the battery but it reduce the cycle life with about 40% compared to 80% cycles.

 

[Nikon201068]

You will get conflicting answers about this.
The main reason is that there are a lot of forum myths. A lot of people got cought by these myths.

For low SOC = the lower SOC the better, when we are talking degradation. Even down to 0% if we only think about the lithium cells.
If the Hv Battery goes too low it shut down to protect itself, and then the 12V battery is mot charged. Most Teslas have a lead scud battery that does not like to be discharged.
So, keeping low SOC but not below 0% displayed (to safeguard the 12V battery) is safe.
This is a calendar aging curve from actual testing. Most teslas have the NCA chemistry, all LR and Performance have in USA.
View attachment 903681
(This is one chart but the research comes up with the same result each time. This is valid data.)

We can clearly see that low SOC is causing less degradation from time.

High SOC cause more degradation but there is not a big difference between 65-100%, so leaving the car at 90% is “safe”.
It cause more degradation than if below 60% but about the same as most people charge to, 70-80%.

For Cyclic aging, low SOC is better and small cycles is better.
100% is worse but not a very big difference to 80 or 90%.

This chart shows NCA cells cycled to 0 % from 100%, about 90% and about 80%.
Normal driving /charging is at the same rate as the grey lines, sometimes hidden behind the blue line.

100-0% cycles did hold about 625 cycles before they lost 20%.
90-0% cycles did hold for 800 FCE (full cycles equivalent) before they lost 20%
80-0% did hold up 1000 FCE cycles before they lost 20%.

View attachment 903682

625 cycles is about 250.000 km or 155.000miles
800 cycles is 320.000 km or 200.000 miles
1000 cycles is about 400.000 km 250.000 miles.
As we see, going down to 0% does not kill the battery.
We also see that 100% will not kill the battery but it reduce the cycle life with about 40% compared to 80% cycles.

Wow. Very informative info. Thank you much

 

[SageBrush]

High SOC cause more degradation but there is not a big difference between 65-100%, so leaving the car at 90% is “safe”.
It cause more degradation than if below 60% but about the same as most people charge to, 70-80%.

You are reading the graph the same way I would read it, but you will have to come up with a reasonable physical mechanism before I take it seriously.
Arrhenius is turning over in his grave. Until proven otherwise, this observation is artefact

 

[ucmndd]

I disagree. Low states of charge are just as bad as (or worse than) high states of charge.

You can disagree all you want, but you’re wrong. Read some of what @AAKEE has posted for enlightenment.

 

[zoomer0056]

Hello TMCers, I like to know how long can the car sit iddling at bottom SOC (let's say around 20% or less) before I should charge it back up to at least 50% or more. Also, how long can the car sit iddling at above SOC (let's say 90% or more) before it should be driven to bring the SOC to more ideal range? Is it few hours or a day or more? Thank you kindly for your inputs.
Edit: I mainly like to know in regard to battery degradation how long or how soon you should charge or drive off to minimize battery degradation.

Plan on loosing 1% a day to help your decision.

 

[AAKEE]

You are reading the graph the same way I would read it, but you will have to come up with a reasonable physical mechanism before I take it seriously.
Arrhenius is turning over in his grave. Until proven otherwise, this observation is artefact

I have read about 200 different research reports. More or less any of these support the same results.
It is not only a question of reading one graph, this is science telling us how it really works.

I did buy 35 pieces of Panasonic 2170 two different batches to test for my self.
I’m not worryed that the research result is not valid but mostly to show others, I make sure the panna 2170 NCA is tested, as we do not have very many tests of these.
I am about one year / one half year into the calendar aging testing, and one thing is clear: the only cells that actually did increase the capacity was the ones stored at very low SOC. All cells stored at 20% or below did increasecthe capacity, all cells above did loose capacity.
So far, I have [tick in the box] graphs following that graph above, except for the ones that increased the capacity (this has been sen in other research reports, so it is covered as well in research).

There is more faulty rumors or myths then it is correct information on forums, and it is time to change this.

You can start by searching for lithium ion + calendar aging and read the research reports.
There is also a lot of internet sites with articles, many if them is fooled by the rumors, spreading myths.
Go for the research reports that actually did test lithium batteries, there we find qualitative data.

Examples:
https://mediatum.ub.tum.de/doc/1355829/document.pdf

ShieldSquare Captcha

https://publications.lib.chalmers.se/records/fulltext/249356/249356.pdf

 

[BitJam]

You can disagree all you want, but you’re wrong. Read some of what @AAKEE has posted for enlightenment.

I already had and I marked it as informative. It was too late to change my previous post.

 

[AAKEE]

I already had and I marked it as informative. It was too late to change my previous post.

Also, it will take time to gain thrust to the insight that what you learned earlier might not be right.

I know there is not many others that spread facts about batteries that comes from research and real tests. Some others do, that theoretically could have been “fooled” by me.

One single source , like me shouldn’t be accepted without thorough checks of the things I say. What anyone that is skeptical should do is to read some of the research I link to, and then search the net for ”lithium ion + calendar aging”or ”lithium ion + cyclic aging” and read some research reports (not online articles on EV sites, or communities: these very often is hit by the myths)

I was hit by some battery myths about 15 year back, and did start reading research.
Some of the myths I learned as myths, but one thing with lithium polymer batteries that seems valid is to not go below 20% when using a lot of power, as model R/C helicopters do.

When I got my M3P, I had a hard time to accept that I wouldnt need a egg between the accxelerator and my foot, as both Lithium ion is less sensitive, and Tesla limit the power at low SOC. Also, the R/C helicopter average about 10C which would be some 800 kW power in a Tesla.

Even today, knowing what I know it is so deeply routed in the spine that the right foot almost do not follow my commands for full power at low SOC. I know, I should know better than that…

 

[AAKEE]

Even Tesla says this.

Its a really good thing that you refer to what Tesla actually states.
Many people refer to things “Tesla says” that actually is not found anywhere in Teslas information (like ”Do not to leave the car at 100%” or 80% is the best SOC” etc.)

Knowing what I know from the research, all information Tesla states match this too.

There is no single information Tesla give us that contradicts the research.

One big point is that Teslas advice most probably will not be the one that reduce the degradation to a absolute minimum.
Tesla would like to give us as few rules and ”do not” as possible to make the Tesla ownership easy. This while at the same time making sure the cars have a acceptable degradation: No or very few battery changes on warranty that was csused by too high degradation. Also, we could guess that if the most of the batteries survive the car, it is good enough.