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Long term storage charging questions

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New Tesla owner and first post to the forum. What could possibly go wrong?

I have searched for answers to my questions, but I haven't found exactly my situation;
plenty questions about storage not plugged in, but mine are about plugged in.
If you disagree, please point me at the post I should have found and I'll deal with it.

2 new Teslas, Model 3 and Model Y, had them about 2 weeks. Located in Texas, so summers are hot.

Going to leave them for about 3 weeks in March and maybe 2.5 months in the summer.
The Y will probably be plugged into a Tesla Wall charger in an attached double garage.
Although the Wall Charger is comissioned for 48A, I'll probably set the car down to take only 18A.
This will be fine in March, but will reach 100F, perhaps 110F in the summer.
The 3 will be plugged into a Mobile charger plugged into a 60-50 socket and the car is set to take only 12A
It will be stored in a larger high roofed metal building. Summer temperatures may reach 95F

Both cars will be set to charge to 50%, and left somewhere in the 40% to 60% range.
Sentry Mode will be off, Cabin Overheat Protection will be off. They don't have summon modes.
Only the Tesla app is used. I'll probably also turn both cars "Off".

If either are below 50% when left, then they should charge to 50% and then stop.
I'm thinking they will then, if left long enough, drain eventually to below 50% SoC and then start charging again back up
to 50%, and then stop, which won't take long. I think that's what the Tesla OM is telling me. Is that correct?

I also read that drains from items that usually come from the HV battery will be fed directly from the plugged in charger.

That being the case, it seems that I could leave Sentry mode on for the 3 week period, because it would be plugged in,
and because it's still a novelty. The novelty should be worn off by the summer.

The harder questions:

If there is a storm induced power outage, will the home chargers start being available to charge again when th epower comes back?
That's assuming they aren't electrically fried. I think I remember reading that the Wall Charger had a built in surge protector.

If the SoC is below 50%, will the car just resume charging? (Presuming the outage wasn't long enough to totally drain the car)

Any thoughts on leaving a car in the small double garage with temps up to possibly 110F? Presumably Arizona has it worse.
As it's plugged in, I could enable COP, but the heat will have trouble leaving the garage, so I doubt it will help.
Maybe they'll both have to go in the 95F - 100F space.
 
...Texas, so summers are hot...
As long as you plug in, you are fine. Even 120V is adequate for your case.
...left somewhere in the 40% to 60% range...
It only allows you to set down to 50%, not 40%.

Sentry Mode will be off, Cabin Overheat Protection will be off.
If you don't mind paying for the electricity bill, there's no harm in keeping them on.
...if left long enough, drain eventually to below 50% SoC and then start charging again back up
to 50%, and then stop, which won't take long. I think that's what the Tesla OM is telling me. Is that correct?..
Yes.
...also read that drains from items that usually come from the HV battery will be fed directly from the plugged in charger...
Low voltage equipments (computers, lights, connectivity, entertainment, sentry mode, BMS...) run on your 12V battery and that battery is recharged by your HV battery.

HVAC uses shore power if you plug your car in. If not, it uses your HV battery.

HVAC does turn on and off automatically even in its deep sleep to protect the HV battery health.

That being the case, it seems that I could leave Sentry mode on for the 3 week period, because it would be plugged in,
and because it's still a novelty. The novelty should be worn off by the summer.
That's fine. No harms when your cars are plugged in.
The harder questions:

If there is a storm induced power outage, will the home chargers start being available to charge again when th epower comes back?
That's assuming they aren't electrically fried. I think I remember reading that the Wall Charger had a built in surge protector.
Yes. If nothing is broken because of the storm. Your car is automatically charged again after a power outage.
If the SoC is below 50%, will the car just resume charging? (Presuming the outage wasn't long enough to totally drain the car)
Yes.
Any thoughts on leaving a car in the small double garage with temps up to possibly 110F? Presumably Arizona has it worse.
As it's plugged in, I could enable COP, but the heat will have trouble leaving the garage, so I doubt it will help.
Maybe they'll both have to go in the 95F - 100F space.
As long as you plug them in, you are covered for the TX, AZ indoor/outdoor extreme heat. Your car has BMS Battery Management System that actively protects your battery from heat and cold damage.

Heat is a concern with a system without active thermoregulation, such as your cell phone that has no HVAC, and it is at the mercy of the nice ambient temperature.

Same with the older Nissan Leaf that only had a passive air cooling system and prayed for nice temperature weather.
 
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