What Percent is Your Tesla Charged to While at Home?

[johnnycnote]

Nope.
Its more like whatever degradation you hsve at 80%, 55% will cut that in half.

First year might give about 5-6% degradation for many people, so 2.5-3% less.
After X years when the 80% would have 15% degradation, the 55% car would have 7.5%

When driving (or charging) the SOC can not be really measured. That is because the SOC is defined by the open circuit voltage (OCV) or resting voltage.

SOC displayed while driving needs therefore to be estimated/calculated.
Example: Having 100% and a estimated capacity of 100 kWh, then after using up 50kWh we should have 50% SOC left.
After parking the OCV is measured and the real SOC is displayed.
After each drive and each charge the SOC is measured when the car is at rest and the SOC is updated. For short drives we probably do not see any difference but after a long drive it might be, if the BMS capacity estimation is not spot on.

Its not bad.

In general, low SOC is god.
From one of the latest research tests the wear is slightly higher below 25% or so, but the cyclic wear is anyhow very low.
You can use the whole SOC range as you like or need.

I use low SOC often and down to ~0% whenever I need.

There are a few simple rules to minimize degradation. I do not list them in this post though.



SC = Service Center, SuC = Supercharging I guess.

Superchsrging to 100% is not dangerous.
The car reduce the charging speed at higher SOC’s, so for the last 10% its rather slow.

I voted 90%, but I've been charging to 100% the last couple of months. Been traveling for work more

 

[nicksp]

I voted 90%, but I've been charging to 100% the last couple of months. Been traveling for work more

Oh no. There goes your battery. JK. You should be fine. There are many who charge to 100% and their batteries are fine.

 

[AAKEE]

Keep in mind that these charts at low speed are not correct (not sure why). The torque doesn't behave that way and it doesn't increase with speed at low SOC as is seen around 30-35mph in these plots. All the power curves should lie roughly on top of each other up to 30mph (which they don't here).

Adding on to @AlanSubie4Life answer:

There is a torque limit applied that keeps the torque at a max level as long as the battery can deliver voltage and current enough for this.

As power is [torque x rpm] we actually have almost no power in the begining of the pull from zero, as the rpm starts at zero.

This is in perfect harmony with the laws of nature.
The driving wheels can only take a certain amount of torque before the spin and loose the good grip. This is the reason to have that torque limitation. Its not possible to put down 500Hp at low speed.

So basically the car has 0hp at 0 mph, but a lot of torque. And at some 70kph/ 43mph the M3P still delivers max torque but it starts to reduce about there.

The power will describe a almost straight line from 0mph and 0kW to 43mph where it starts to bend down and reach the about 500hp max at some 85 kph/ 53mph or so.

The trick question would be, how many hp does the Plaid deliver at very low speed? 1000? Nope!

(I did not find a official picture for the M3P, so I webt with this instead).

It would be possible or even really easy to let the car/engibes put put much more torque at low speeds (resulting in higher power) but we would only have wheel spin as a result that would need to be restricted by the ASR.
Also,,having instantly much more torque would need a beefier transmission, not to break causing a higher weight of the car.

As the need for power is not that high at lower speeds, the low SOC do not cause a massive drop in low speed acceleration.
But as the battery droop in voltage at load with low SOC there will be a reduction in torque as well, if the battery is not wsrm enough to not drop tso much as it affects the torque.
Living in a warm climate at summer probably reduce the ”loss” (almost)completely on a 0-40 mph drag but living cold or not in the warm summer makes us notice that the pull is weaker.

Charging late at max power will heat the battery, and the heat will be there st the next stop light pull!
(Charging late is one of the things to do to reduce calendar aging so a double win).

 

[AAKEE]

You should be fine. There are many who charge to 100% and their batteries are fine.

Exactly!

All other Panasonic NCR18650 and 2170 that Panasonic makes, (and all other brands making lithium batteries) are actually made to be charhed to 100% and to be discharged to 0% without breaking.

It is fun to see how people think tesla on purpose use specially made cells that can not stand 100% and 0%. The people at Teslas design department are evil and like our batteries to die

No, of course not.

The batteries do not get damaged staying at 100%, but the rate of degradation is higher than at low SOC. In most normal cases there are no or only small differences in calendar aging between 80-90-100%.
This is the reason Tesla do not write anything in the manual about not leaving it at 100%.
(In most cases there is no reason to leave it at 100%, so we can do it if we need to).

 

[DrChaos]

For example, I kept my car's limit at 50% for all but about 10 days in my first year. I had degradation from 358 miles when new to about 342 in 12 months, that's 4.4%. Temperatures were moderate. Less than 5-6% typical 1 year but more than half of typical. And of course BMS calibration uncertainty adds to this.

One more update on my personal car: the above measurement might have been pessimistic because of BMS calibration error. A full charge recently gave 344 miles at 16 months.

I am now setting charge limit to a random number between 50 and 55% each night, that seems to get more BMS recalibration and the extrapolated range is 343-346.

In a nutshell: following the science really works, keeping SOC <= 55% almost every day lowers degradation rate, and I learned it all here on TMC forums

 

[nicksp]

Exactly!

All other Panasonic NCR18650 and 2170 that Panasonic makes, (and all other brands making lithium batteries) are actually made to be charhed to 100% and to be discharged to 0% without breaking.

It is fun to see how people think tesla on purpose use specially made cells that can not stand 100% and 0%. The people at Teslas design department are evil and like our batteries to die

No, of course not.

The batteries do not get damaged staying at 100%, but the rate of degradation is higher than at low SOC. In most normal cases there are no or only small differences in calendar aging between 80-90-100%.
This is the reason Tesla do not write anything in the manual about not leaving it at 100%.
(In most cases there is no reason to leave it at 100%, so we can do it if we need to).

People get obsessed with these charging and discharging numbers to the point of panic. There was a study done on 12.5k cars which used supercharging and charged to 100%. Those batteries held up pretty well. If Tesla sells me a car with 310 miles then that's what I'm going to go by. I

 

[DrChaos]

People get obsessed with these charging and discharging numbers to the point of panic. There was a study done on 12.5k cars which used supercharging and charged to 100%. Those batteries held up pretty well. If Tesla sells me a car with 310 miles then that's what I'm going to go by. I

the people who supercharged often probably didn't have home charging, and they likely drove their cars down to lower SOC on average than people who set their car to 90% and stayed between 75-90% almost every day, which is not great for calendar aging. So as we've been saying, cyclic aging doesn't matter that much until car is very old unless you drive tons of miles commercially.

What is true is that people outside of here concentrate much too much on supercharging and cyclic aging, and not calendar aging and SOC, which is what actually matters. Look at all the statistics collecting apps, the x-axis is always 'miles/km driven', and not age. Legacy from ICE thinking---and even there engine wear should go as hours in use, not distance though suspension ages as miles. Commercial engines (aircraft/heavy equipment) measure hours.

 

[DrChaos]

Exactly!

All other Panasonic NCR18650 and 2170 that Panasonic makes, (and all other brands making lithium batteries) are actually made to be charhed to 100% and to be discharged to 0% without breaking.

It is fun to see how people think tesla on purpose use specially made cells that can not stand 100% and 0%. The people at Teslas design department are evil and like our batteries to die

No, of course not.

The batteries do not get damaged staying at 100%, but the rate of degradation is higher than at low SOC. In most normal cases there are no or only small differences in calendar aging between 80-90-100%.
This is the reason Tesla do not write anything in the manual about not leaving it at 100%.
(In most cases there is no reason to leave it at 100%, so we can do it if we need to).

NMC does have fast degradation at 100% more than 90% right? And most cars outside Tesla are NMC, not NCA.

 

[AAKEE]

NMC does have fast degradation at 100% more than 90% right? And most cars outside Tesla are NMC, not NCA.

There is not very much calendar aging tests om the common NMC used in many EV’s.
There is a lot of research doing cyclic aging tests though. The researchers focus on cycles.
In general, what we see from calendar aging testa they do not seem to differ very much.
LG NCMA (NMC811 but 80% nickel, 8% cobalt, 8% manganese and 4% aluminium) seem to hold up very good. Still about half calendar aging at 50% vs 100% but the 100% is not bad at all at normal temperatures.

NMC in general are doing about as NCA but more sensible to high temperatures + high SOC. This “issue” is probably reduced in latest generations.
There is also quite a few NMC tests showing that 80-90% is causing about the same calendar aging as 100% so in general we can not say that NMC is more sensitive to 100%.

 

[AAKEE]

People get obsessed with these charging and discharging numbers to the point of panic. There was a study done on 12.5k cars which used supercharging and charged to 100%. Those batteries held up pretty well. If Tesla sells me a car with 310 miles then that's what I'm going to go by. I

Regardless of that study we know that supercharging/fast charging causes lithium plating which in the long term/many fast charges cause short cuts in the cells.

As @DrChaos wrote, there might be reasons for the outcome of the research result in that case.

Also, knowing about a few EVs where the battery broke due to internal cell shorts which was extensively supercharged, they did not show very high degradation before the battery did break down.

 

[KenBlub]

I’ve seen and believe the calendar degradation graph regarding my NMC battery. My charge limit is 50%. I set my car to charge every night and be charged before I leave in the morning. My longest drive in a day is 50 to 32%. The drive gets me there and back by 2:00pm

While it’s certainly not difficult to set up a charging schedule to charge at night, I’d rather just plug in when I get home if I can still minimize degradation

Looking at the degradation difference between 25 and 50% with NCM, any reason why I shouldn’t just plug in every day at 2:00pm and charge to 50% ? It would then sit at 50% overnight instead of 30% but the graph suggests to me I’d incur no extra degradation.

Will my “plan” work?

 

[E90alex]

The degradation difference should be minimal.

But if you leave at a set time everyday, there’s other benefits to complete charging right before use versus letting it sit charged overnight. The battery will be warmer which is more efficient and enables more regen in cold weather.

 

[KenBlub]

The degradation difference should be minimal.

But if you leave at a set time everyday, there’s other benefits to complete charging right before use versus letting it sit charged overnight. The battery will be warmer which is more efficient and enables more regen in cold weather.

Good point. Thanks. Not so cold now in Ohio but it definitely will get colder soon. I’m trying to develop a system to make my laziness work for me.

 

[AAKEE]

I’ve seen and believe the calendar degradation graph regarding my NMC battery. My charge limit is 50%. I set my car to charge every night and be charged before I leave in the morning. My longest drive in a day is 50 to 32%. The drive gets me there and back by 2:00pm

While it’s certainly not difficult to set up a charging schedule to charge at night, I’d rather just plug in when I get home if I can still minimize degradation

Looking at the degradation difference between 25 and 50% with NCM, any reason why I shouldn’t just plug in every day at 2:00pm and charge to 50% ? It would then sit at 50% overnight instead of 30% but the graph suggests to me I’d incur no extra degradation.

Will my “plan” work?

It is OK, but in general, charge late.

My collegue with a M3LR LG NMC 78.8 kWh does that and had 78kWh nominal full pack after > 1 year and 40K km.

 

[KenBlub]

It is OK, but in general, charge late.

My collegue with a M3LR LG NMC 78.8 kWh does that and had 78kWh nominal full pack after > 1 year and 40K km.

I assume you mean your colleague charged “late” and not “early” like I proposed.

 

[AAKEE]

I assume you mean your colleague charged “late” and not “early” like I proposed.

Yep.

He:
-Charges late
-Charge to 55-60% ( NMC has the "step" at 62% true SOC so 60% is safe)

 

[3sr+buyer]

Looking at the degradation difference between 25 and 50% with NCM, any reason why I shouldn’t just plug in every day at 2:00pm and charge to 50% ? It would then sit at 50% overnight instead of 30% but the graph suggests to me I’d incur no extra degradation.

If you have time-of-use metering, or just want to avoid using electricity during peak hours, you may want to check whether starting charging at 2pm will complete before peak hours.

 

[KenBlub]

If you have time-of-use metering, or just want to avoid using electricity during peak hours, you may want to check whether starting charging at 2pm will complete before peak hours.

Thanks. My plan has no off peak so it costs me $0.12 per kw no matter when I charge. Going from 50 to 30% costs me just under 70 miles and my M3 LR charges at 44 miles per hour so it’s only a 2 hour charge.

It’s easy for my lifestyle to keep a low SOC and I’m just trying to learn what parameters are most important. I guess I was asking if storing at 30% SOC made a difference vs storing at 50% and I’m learning the answer is “yes”.

 

[DrChaos]

I’ve seen and believe the calendar degradation graph regarding my NMC battery. My charge limit is 50%. I set my car to charge every night and be charged before I leave in the morning. My longest drive in a day is 50 to 32%. The drive gets me there and back by 2:00pm

While it’s certainly not difficult to set up a charging schedule to charge at night, I’d rather just plug in when I get home if I can still minimize degradation

I guess I don't understand the problem---I plug in when I get home but the charging is automatically at night and complete by 6am (end of my low cost electricity period).

If you have a time of use electricity plan (which can be beneficial with EVs), later charging is better as well.

 

[AlanSubie4Life]

Thanks. My plan has no off peak so it costs me $0.12 per kw no matter when I charge. Going from 50 to 30% costs me just under 70 miles and my M3 LR charges at 44 miles per hour so it’s only a 2 hour charge.

It’s easy for my lifestyle to keep a low SOC and I’m just trying to learn what parameters are most important. I guess I was asking if storing at 30% SOC made a difference vs storing at 50% and I’m learning the answer is “yes”.

If I were you in your apparent specific situation, I would just charge right away. It just helps ensure that in the event of unexpected needs later in the evening, I have higher likelihood of having enough charge to stay above 20% when parking (for feature use).

You’re already getting most of the benefit with your ~50% charge level, and only getting marginal benefit for further average charge level reductions (they would help of course).

That way it is more convenient. You’re already sacrificing a small amount of convenience (easily addressed by remembering to charge car to higher level when needed - but possible to forget!); no pressing need to give up more.

For me, if I did not have massive cost reductions for charging overnight (something like 4x cheaper), I would just start charging immediately to 55% upon plugging in.

You could also split the difference and only delay charging when the weather is warm. In winter time it matters a bit less, assuming your garage is not climate controlled.

Just make it as convenient as you need it to be.