Max charge to leave at car for a week

90% is a normal charge to value no matter what. I am not sure what the issue you are worried about is.

Unless you have a 100D and a tailwind, I doubt you are going to make the 200 mile return trip after losing 10% to 20% in vampire drain, so you are going to have to charge somewhere on the way home.

 

you could make some changes to get less vampire drain on the battery as well...

1 turning off cabin overheat protection
2 Always Connected' must be turned off.
3 Energy Savings' must be turned on.


as far as long term usage, charge to what you need on a daily basis however less charge will equal more lifespan as you have read. Charging to around 70% will give you much more lifespan vs 90 but if you really need to use more then 70% of your battery then charge more. Also if you use less then you could charge less on a daily basis. Personally I charge to 60% daily but if I know I need to travel further tomorrow ill set my car to charge more tonight to be prepared.


Heres a chart showing a general example of how charge percentage of a lithium ion battery relates to they number of cycles you get. These aren't exact numbers for a Tesla but it gives you an idea of how reducing your daily charge limit can increase the cycle count.

 

The notch at the end, 90%, is the top of the daily charge level. The range charging starts after that.

There has been a debate for years about 80% being ideal. I see this quote from Jeff Dahn, a renowned battery researcher in Electrek that states he thinks that 70% is the ideal daily charge level. The manual states 70% to 90% for longest life. So going to 90% a few times is certainly not going to be a big issue.

 

I charged my Model S to 90% every night for five years, except when I charged to 100% for trips. No worries. Did you know that early versions of the firmware, before the slider was introduced, had only two settings “daily” and “trip”? The daily setting was 92%.

Whether you routinely charge your car to 80% or 90% may give a statistically significant difference after many years but it’s not clinically meaningful.

 

The ATL airport parking lots/structure has Chargers at no additional cost. They are slow (4-5mph) but that’s not a problem since most EVs will be plugged in for days. Just leave it plugged in and you’ll be at 90% when you return. Vampire drain will happen but once it drops 10% it will top you off again. You can also remotely set the charge to 100% the night before you return.

 

90% is fine. I generally leave my car on a charger at the airport when I travel. when I board my flight home, I set it to 100% range charge on my app so I can have a full battery leaving the airport.