So, in my
opinion, I wouldn't own an EV unless I could charge at home in some way. It's way more hassle, and you don't get the often-cited benefit ("Stop for charge? My car is always full every morning!") while lacking the quick fill up capability of a gas vehicle.
We have the LR. We started with only basic 120V charging, and the car went at least 120km every day (75mi). Even with charging 100% of the time it was at home, we'd still need to stop somewhere once a week for some extra charge (one brunch place nearby a charger got extra business from us during this time). Going to the next town over means we'd always need to stop at the Supercharger to make it through the next week. This actually turned 30 minute trips into 70 minute trips (one-way), as we often had to overshoot our destination to get to the charger and then sit for charging.
Story time. We recently were in Montrose, CO without charging at the hotel in cold weather. My wife was at work during the day but didn't take the Tesla. For the few short trips we did (e.g. dinner in the evenings, and only sometimes, sometimes a lunch run) it was
an absolute chore to keep that thing charged. Of the 3 or so chargers available, only 1 was convenient for stopping at during other activities. Even then, it was too far from many places and we often had to get the whole group of workers to pick a different place for dinner
just so the EV could charge. A couple times I went an hour out of my way to hit a CHAdeMO station so I'd spend less time overall charging (just 3 hours!). Many times though, I just took the dog and sat at the L2 charger watching YouTube videos for hours. This was a good simulation of not having charging at home, and I want nothing to do with it. Too much wasted time and fussing around with where I'm "allowed" to go so there's a convenient charger nearby, not to mention the trips and waiting explicitly for charging.
What you will need to do is build some new habits to make this work:
- Use public charging habitually. Use it everywhere if stopped for 10 minutes or more. Change where you frequent (groceries etc.) so that it's reasonable near a charger. If you haven't used it yet, I highly recommend PlugShare for finding chargers and checking in.
- Get used to walking further (since you parked further for charging). This is a benefit of sorts, but don't forget an umbrella!
- Never get to the point where a station not being available would ruin your day. This is public charging, someone else may be using it. Basically, don't run your charge down very low if it's preventable by charging more frequently (which is less convenient, but missing a critical charge is even more so).
- Plan for a lot of extra time needed when going places. Getting anywhere where a Supercharger is needed will take more time than you think (and because you don't have at-home charging, this will happen more frequently) due to both the detour and the charge time.
You
will need to turn these off, and ensure any new features that cause battery drain are turned off:
- Sentry Mode (consumes about 14%/day for SR+)
- Summon Standby (probably consumes the same as Sentry, though if one is on the other doesn't require more power I don't think)
- Cabin Overheat Protection (if it's parked in the sun or somewhere warm)
- Don't access the app often. This wakes the car and starts consuming the same 14%/day until it falls asleep (generally within a few minutes, but sometimes it stays awake longer).
You will need to keep in mind...
- Short hops with heating the cabin are the worst for battery drain. Double the expected usage (i.e. if showing 250mi range, assume it's actually 125mi for your short hop purposes).
- The LR can charge faster at some L2 stations than the SR+, but stations with this much power available are actually pretty rare (generally they're Tesla wall chargers, not J1772 plugs).
And to address your direct questions...
- I wouldn't park the car with less than 50% (to give buffer for the next day). Less could be fine, but this wouldn't be negotiable in Winter climates if you need to go 50 miles.
- Typical drain according to old Stats app numbers is equivalent to about 60W. For a 12h period, that's not quite 1% on the SR+. This probably includes the car waking itself, vampire drain, etc. and isn't the most accurate number. In your case, I'd expect it to be slightly less since it's not plugged in.
- Drain on a cold night outside is potentially much, much worse. There's contention on here about at what point it will heat the battery, by how much, or if it does at all. Most people in cold conditions don't leave the car unplugged so wouldn't really notice. In my apparently rare experience, you can lose a lot (equivalent to 15% on the SR+). I don't know if that would happen at 20F.
- Preconditioning the cabin now sometimes preheats the battery as well, which draws a lot more power. I too choose to retain a significant other and will choose heat anyways, but try to delay it until you get in the car if the battery is lower than you'd like. The heat starts blowing in about 30 seconds.
- Long-term storage various significantly. I've seen anywhere from 1%/day to 1%/week. Leaving it unplugged actually seems to help, anecdotally, so I'd expect closer to the 1%/week mark for you. If it's cold, I'm not sure how this would work though.
- With the LR, some things actually do change significantly. For one, it adds more range faster at a Supercharger. Having that extra 70mi is also quite significant when you have only a few to play with already. See below. Things like Sentry and the car being randomly awake take the same power from SR+ and LR, but the LR can supply that power for longer.
- If you charge to 90% the night before, you can expect anywhere between 87-92% in the morning due to various factors.
Effective Daily Range:
This is what I use to tell people the actual daily range.
You will only charge to 90% maximum and keep it above 10% minimum. Thus,
only 80% of your capacity is actually used on a day-to-day basis. In terms of "range", that's also 80%.
For a "warm winter", using an extra 30% for the same range is normal in an LR (this would actually be worse in the SR+, as the heat power is the same but with a smaller battery). Add in some other minor losses and you're at 60% of rated range.
That means a 250mi-rated SR+ can be expected to get you around only 150mi within 10-90%.
For a 320mi-rated LR, that's 192mi.
If you wanted to use 20%-80 like many do, that's only 46% of rated. 115mi in the SR+, 147mi in the LR. And keep in mind I didn't factor in that the SR+ should actually be draining more compared to the LR in terms of percent in Winter.
Happy news, it's not Winter all year long!?
tl;dr: It's not impossible but it's highly impractical. You need to love it so much that you're OK with all the extra time and steps needed to keep the car moving. These are my personal observations (plus similar data from other users on here).