Leave car plugged in while I'm away?

[Mikedrives]

2019 Model 3 SR+, software limited to SR, 11K miles. I'm going away for six days with the forecast for hot sunny days, 88º, etc. I can park the car in the back of the house and leave it plugged in. It will have partial sun most of the day, full sun from 4-7pm.

Should I leave it plugged in? When it hits 115º inside it turns on the AC, correct? I have it set to charge to the top of the daily driving range. But I've never known the car to re-initiate charging after it has stopped, and don't know if that matters.

Or should I park it under the shady trees out front? I don't much care how much less charge it has when I return, I just wonder what best practices are, and what is best for the long-term life of the battery. Thank you!

 

[Leeclanual]

It won’t hurt to leave it plugged in...

 

[DirtyT3sla]

Absolutely yes plugged in. I personally would keep the charge capped at 60% or 70%, but anywhere 90% or below is fine. You can leave Cabin Overheat Protection on to keep it cooler during the sunny days. And since plugged in, feel free to keep checking the app to see how it's doing!

 

[1.21GW]

leave it plugged in. no worries

Tesla engineers did much of the thinking and battery management for you... The car will protect itself.

"A plugged in Tesla is a happy Tesla"

 

[EV3_]

Correct me if I'm wrong, but doesn't Cabin Overheat protection stop after 12 hours?

 

[Mikedrives]

Thanks, all. But does it ever really draw more juice after it has stopped the initial charge? I don't know why I care, but I thought that was the point of keeping it plugged in, yet I've never known it to start re-charging. And Cabin Overheat Protection On is the default, right? I didn't even know you could defeat it.

 

[1.21GW]

The car will initiate charging again when
-Battery level drops below your set charge point
-User turns on HVAC to precondition the cabin
-Cabin overheat protection starts

I'm sure there are other reasons, but when the car is plugged in, it will pull power from the wall as a priority whenever the vehicle needs to use power.

 

[hgmichna]

I agree that leaving it plugged in is good.

If you are away, set it to charge to the lowest point, which is 50%, to conserve the battery as much as possible.

Before you need it again, you can raise the charge level through the app to whatever you need.

 

[Rocky_H]

But does it ever really draw more juice after it has stopped the initial charge? I don't know why I care, but I thought that was the point of keeping it plugged in, yet I've never known it to start re-charging.

The car will initiate charging again when
-Battery level drops below your set charge point

I'll add a little more detail to this. You may not have seen it reactivate because it doesn't always restart charging as soon as it loses a hundredth of a percent or some tiny insignificant drop below your set point. If it did, it would never be able to stop charging! So it does have a little bit of flexibility in there of around 3% or so that it would have to run down before it will determine it's worth it to reconnect and do another top-up charging cycle.

And the other scenario is if you have a scheduled charging time set, like midnight. It will drop by 3% or more, but still wait until that scheduled time comes before it will run another recharging cycle.

 

[Mikedrives]

Ah, thanks, that all makes sense. That explains why I've never seen it topping itself off, if I'm asleep when it happens. Which brings to mind two almost unrelated questions:

1.) Does anybody ever really get paid to take juice off the grid? I understand it in the hypothetical, that the utility pays people to scrub extra juice off the grid when they can't ramp down production slow enough, which I imagine happens on cool nights that follow hot summer days that require peak power. Here in Illinois, we are allowed to sell back power to the grid (not that I do that yet) and I have variable rate pricing.

2.) The way you worded: " it's worth it to reconnect" made me think of Elon's dream of having a snake-charmer style prehensile charger come to life and connect itself without human help to charge your car. Do you think that will ever happen? Seems ridiculous, as if it is so hard to connect the charger yourself. (What next, have the cars drive themselves? Ridiculous.) But then again, if he can make rockets land themselves by blasting off backwards, maybe that's easy.

 

[camalaio]

All good points. I'd park it in the shade just because, as long as it's not under one of those sappy trees that dumps those tiny little sap droplets all over your car!

2.) The way you worded: " it's worth it to reconnect" made me think of Elon's dream of having a snake-charmer style prehensile charger come to life and connect itself without human help to charge your car. Do you think that will ever happen? Seems ridiculous, as if it is so hard to connect the charger yourself. (What next, have the cars drive themselves? Ridiculous.) But then again, if he can make rockets land themselves by blasting off backwards, maybe that's easy.

Nah. It's of course entirely possible (see: rockets etc.), but the cost vs. benefit is extremely bad. Consumer products at some point always involve a cost vs. benefit analysis, at least ultimately at the customer end. I'd never pay the $1000+ (probably much more considering it would be a low-volume product) required to have a mechanical snake (un)plug the car when I'm right there and can spend the 5 seconds and minimal effort to do it myself, which kills the idea for such a product. A dozen people might actually buy it, but it's not worth the one-time manufacturing and R&D costs even if it was sold for $10,000/snake.

Of course, some people buy FSD for $7000 just for the auto lane change which is even less effort than plugging in the car, so perhaps I've misjudged the market!