Daily Charge Rate - 80/85/90 % ?

[DanCar]

This matters more during summer than winter. Higher temperatures allow for increased charging capacity but cause batteries to degrade faster. If battery is 86 degrees or above then degradation is 20% more than 68 degrees according to battery university: Discharging at High and Low Temperatures

 

[Marcust99]

Stupid Q, but can you set the charge limit as a percentage as opposed to using the slider? I can't see how to do this?

 

[Gor-Gor]

Stupid Q, but you do you set the charge limit as a percentage as opposed to using the slider? I can't see how to do this?

I believe you can only use the slider, and I'm basing this off the owner's manual.

 

[DanDi58]

Stupid Q, but can you set the charge limit as a percentage as opposed to using the slider? I can't see how to do this?

Not sure I understand the question - that's how you set the percent upper limit, by using the slider.....

 

[Marcust99]

Not sure I understand the question - that's how you set the percent upper limit, by using the slider.....

Right, but say you want to set the limit to 75%. Just by using the slider, how do you know you're at 75 and not, 70 if there's no numeric value showing?

 

[DanDi58]

Right, but say you want to set the limit to 75%. Just by using the slider, how do you know you're at 75 and not, 70 if there's no numeric value showing?

If you're talking about the phone app, the number shows in the lower left hand corner of the battery icon as you slide.

 

[Fourdoor]

Right, but say you want to set the limit to 75%. Just by using the slider, how do you know you're at 75 and not, 70 if there's no numeric value showing?

From what I have read here in another thread, the charge limit slider in the phone app has a numeric value when you are adjusting it, so use your phone to set your charge limit.

Keith

 

[Zoomit]

I'm not sure I'm following.. What I meant was that 10 charges from 65 - 75% = 1 cycle.. So, they charge from 65 to 75, discharge to 65 and repeat until they reach one full cycle.. 1 cycle is not the same as one charge.

The authors clearly indicate one cycle in their study is, for example, from 75 to 65 and back to 75. This is not how a battery discharge/recharge cycle is normally defined, hence the need to normalize the data to distance. It’s not a great dataset, but it surfaces occasionally and appears to be frequently misinterpreted.

 

[Fourdoor]

The authors clearly indicate one cycle in their study is, for example, from 75 to 65 and back to 75. This is not how a battery discharge/recharge cycle is normally defined, hence the need to normalize the data to distance. It’s not a great dataset, but it surfaces occasionally and appears to be frequently misinterpreted.

Every battery study I have seen defines one cycle as any combination of charging and discharging that totals up to one full to empty and back to full equivalent. If your study is 100 to 50 and back to 100 over and over again, then two charges = one cycle If your study uses 75 to 25 and back to 75... you guessed it, two samples = one cycle. If your study uses 70 to 60 and back to 70 then it takes 10 samples to = one cycle. No idea what you are talking about with normalizing the data to distance... batteries in devices that travel a distance is a new phenomenon... battery testing has existed from not long after the first battery was invented.

They say in that study that they repeat the charge discharge loop repeatedly in the DST until the stop level is reached. The confusion is caused by them not defining "stop level" The stop level is defined by how many discharge / charge loops it take to be equal to one full discharge /charge cycle. For a 10% SOC spread it takes 10 loops to reach stop level. For a 25% SOC spread it takes 4 loops to reach stop level... you do not need to "normalize" the data in their graphs.

Keith

 

[rijc99]

Right, but say you want to set the limit to 75%. Just by using the slider, how do you know you're at 75 and not, 70 if there's no numeric value showing?

I have my car display to show percentage so when I use the slider in app it shows percentage.

 

[Zoomit]

Every battery study I have seen defines one cycle as any combination of charging and discharging that totals up to one full to empty and back to full equivalent. If your study is 100 to 50 and back to 100 over and over again, then two charges = one cycle If your study uses 75 to 25 and back to 75... you guessed it, two samples = one cycle. If your study uses 70 to 60 and back to 70 then it takes 10 samples to = one cycle. No idea what you are talking about with normalizing the data to distance... batteries in devices that travel a distance is a new phenomenon... battery testing has existed from not long after the first battery was invented.

Keith

I totally understand, hence why I quoted their statement that indicates they did something different. Please read the paper and suggest an alternative interpretation of their test description.

 

[Fourdoor]

I totally understand, hence why I quoted their statement that indicates they did something different. Please read the paper and suggest an alternative interpretation of their test description.

I read the section of their paper on the DST. You are misinterpreting it. They did the same as every other battery tester. The part that confused you is they didn't DIRECTLY define "stop level". It is clear in the context of the relevant paragraph that "stop level" = "number of charging loops required to complete one full cycle". But they didn't DIRECTLY state this, so you can interpret it as you please and I can talk until I am blue in the face. You invested a lot of time and effort into interpreting their graphs. Human nature says that you will not re-read the paragraph with an open mind after poring all of this effort into your interpretation, so I am wasting my breath.

Keith

 

[Marcust99]

View attachment 671320
I have my car display to show percentage so when I use the slider in app it shows percentage.

I figured out the issue. The default preference on the car is to show measurment by distance and not percentage. So I just changed it to %. All good!

 

[Zoomit]

Human nature says that you will not re-read the paragraph with an open mind after poring all of this effort into your interpretation, so I am wasting my breath.

Please reread your (condescending) remark and then ponder the most logical reason why the top line dataset extends to nearly double the number of DST cycles as the bottom line.

 

[Marcust99]

Saw a Tweet from Elon where he said charging to 90% was fine but no more as regen braking wouldn't work. If Elon says it's fine,
I gotta think it's OK...

 

[Rocky_H]

Saw a Tweet from Elon where he said charging to 90% was fine but no more as regen braking wouldn't work. If Elon says it's fine,
I gotta think it's OK...

Musk is a CEO who is trying to sell a product people will want to use. Telling people to only charge to 50% would not work for that. So he's not saying what is most ideal, just something that is fairly reasonable. So that's why it shows the DAILY charge limit area from 50% to 90%. Pick some reasonable level that works for you in that area somewhere.

Think about it for a second. If you use a limit of 91% for a few days or more, the car will show a warning on the screen that doing that constantly is harmful to the battery, so why in the world do people still think that 90% is somehow perfect? That makes no sense at all. Going a bit farther down from the top is still helpful.

 

[patnshan]

Saw a Tweet from Elon where he said charging to 90% was fine but no more as regen braking wouldn't work. If Elon says it's fine,
I gotta think it's OK...

I go to 90 and it's fine for me. No issues on STATS with battery degradation yet.

 

[Iceman23]

I understood charging slightly different.
Keeping this mid charge level will give you weaker range numbers even though it’s still strong.

example, I charge 40-70% all winter and then try a 100% charge and my full range is only 264 mi vs the 306 mi it can charge to.

MTP fix this I run the battery down to about 5% and then give it a full charge to recover all of my range back.

I only do this about every 90 days roughly so it’s not often to keep the BMS and battery’s happy.
Feel free to correct me and if you want to help everyone in 1 reply, please list it out in steps on how we should maintain best battery health

 

[metroplex]

I only use about 10% of SOC on a daily basis. Looking at the graphs, they cover a wider range of DoD and Avg. SOC
Should I just charge to 70%, run down to 60% and charge on a daily basis? Or do I really want to hover around 50% SOC (So charge to 65% run to 55%, etc)?

Or do I want to just set it to charge to 80% and run it down to 70% on a daily basis?

 

[jcanoe]

I only use about 10% of SOC on a daily basis. Looking at the graphs, they cover a wider range of DoD and Avg. SOC
Should I just charge to 70%, run down to 60% and charge on a daily basis? Or do I really want to hover around 50% SOC (So charge to 65% run to 55%, etc)?

Or do I want to just set it to charge to 80% and run it down to 70% on a daily basis?

Try not to obsess about the charging level and charging frequency of your Tesla Model Y. Any routine where you charge daily or frequently and maintain the battery state of charge (SOC) between 50% and 90% is fine.

Ask yourself, if you arrive home down 10% from the set maximum SOC at the end of the day how many hours would it take to bring the charge level to 90% for starting out on a longer drive or trip. If longer than a couple of hours perhaps it would be better to raise the daily charge limit so that you can always top up before leaving on a trip with little time or notice.