Leave plug connected overnight?

[HankLloydRight]

But why? Why not use this awesome car?

Because all winter we've had a lot of snow and ice.. and along with that comes lots of road salt/grime and more accidents and really bad drivers who don't know how to drive in the snow.

So to preserve the Model S from both road hazards (bad drivers and salt/dirt/snow/ice), I drive my 2002 M5 as my "winter beater".

Now that the weather is finally turning warmer and the snow is almost gone, I'll be taking the MS back out for daily driving, and moving the M5 to the street in the back for long-term summer storage, or when I need to drive a car into the city.

And once the temps consistently hit 60 degrees or better, I'll take off the 19"s with all-season tires and put back in the 21"s with summer tires.

 

[mikeash]

Since the OP started out by asking a really basic question about whether or not it is OK to leave the car plugged in all the time, I figured it was better to be explicit about the timed charging, as he might have had no idea that it was even an option.

I certainly don't mind the elaboration, in any case!

As far as topping off goes, I wonder what the difference is. Could be down to firmware versions, car age, wall connector differences, power quality... I hesitate to go on. Mine isn't consistent about it, but it does happen sometimes.

 

[brucet999]

Just to be a little more specific about what happens when you plug in....

if you turn on the climate control (either using the app or by opening the door) the car will turn on the wall voltage (if it's not already on from charging) and run the climate control from the charging power rather than the batteries. ... Also saves some wear on the batteries, for whatever that's worth.

Are you sure of that? I don't think the power consumed while plugged in is somehow bypassing the battery, so how would "wear" on the battery be reduced?

 

[LucM]

Just to be a little more specific about what happens when you plug in....

When you first plug in, the car will start charging, and will continue to charge until it reaches the charge limit. You can set the charge limit in the charging screen in the car, or in the smartphone app. I believe the default limit is 90%.

Once it hits the charge limit, the charge stops and the wall voltage is disconnected. I believe you'll hear some relays click when this happens, although I haven't been present for the event myself. At this point, the car acts more or less as if it were unplugged.

Now, if the battery charge drops by more than a certain amount (not sure exactly how much, but a few miles of rated range) then the car will reconnect to the wall voltage and charge back to the set limit.

Similarly, if you turn on the climate control (either using the app or by opening the door) the car will turn on the wall voltage (if it's not already on from charging) and run the climate control from the charging power rather than the batteries. This means you can pre-heat or pre-cool the car without impacting range if it's plugged in at the time, which is really nice. Also saves some wear on the batteries, for whatever that's worth.

Just to clarify, the car won't start charging once you plug it in if you have it set to start at a particular time.

 

[mikeash]

Are you sure of that? I don't think the power consumed while plugged in is somehow bypassing the battery, so how would "wear" on the battery be reduced?

Not sure, but that's my understanding. It's not as if the battery has separate in and out terminals. The battery at any moment is either charging, discharging, or idle, it can't both charge and discharge at the same time. If you're drawing power from the wall and using power in the HVAC system, it would have to bypass the battery, wouldn't it?

 

[Larry Chanin]

yes, you have a really smart car... it charges at the time you tell it, and stops at the limit you set... uses the power plug for "vampire" drain outside that time... No harm no foul...

PS; don't know about Florida, but CA has special EV rates that are terrific if you charge after midnight.

Florida has no EV rates.

Larry

 

[AmpedRealtor]

Hey guys, just picked up my Model S today. I'm charging at home with the NEMA 14-50 at 30 miles an hour. Of course the car will be fully charged sometime in the night, is it ok to leave the plug connected to the car and wall outlet all night?

You really should read your owner's manual.

 

[jerry33]

Not sure, but that's my understanding. It's not as if the battery has separate in and out terminals. The battery at any moment is either charging, discharging, or idle, it can't both charge and discharge at the same time. If you're drawing power from the wall and using power in the HVAC system, it would have to bypass the battery, wouldn't it?

Well, drawing from shore power is just an easy explanation. It's more like shore power charges the battery at the same rate that power is taken out. If you watch after a preheating session, you'll see that charging occurs for about a minute after the charging stops. If there really was a separate path, it would stop immediately.

 

[Larry Chanin]

You really should read your owner's manual.

More specifically the owner's manual states:

Caution: Tesla strongly recommends leaving Model S plugged in when not in use. This maintains the Battery at the optimum level of charge.

Larry

 

[TsRocket]

Hey guys, just picked up my Model S today. I'm charging at home with the NEMA 14-50 at 30 miles an hour. Of course the car will be fully charged sometime in the night, is it ok to leave the plug connected to the car and wall outlet all night?

Have left mine as long as two months in my garage, plugged in. All was fine.

 

[brucet999]

You really should read your owner's manual.

When I was in the Navy that would have been expressed as RTFB.

 

[Lior]

Just to be a little more specific about what happens when you plug in....

When you first plug in, the car will start charging, and will continue to charge until it reaches the charge limit. You can set the charge limit in the charging screen in the car, or in the smartphone app. I believe the default limit is 90%.

Once it hits the charge limit, the charge stops and the wall voltage is disconnected. I believe you'll hear some relays click when this happens, although I haven't been present for the event myself. At this point, the car acts more or less as if it were unplugged.

Now, if the battery charge drops by more than a certain amount (not sure exactly how much, but a few miles of rated range) then the car will reconnect to the wall voltage and charge back to the set limit.

Similarly, if you turn on the climate control (either using the app or by opening the door) the car will turn on the wall voltage (if it's not already on from charging) and run the climate control from the charging power rather than the batteries. This means you can pre-heat or pre-cool the car without impacting range if it's plugged in at the time, which is really nice. Also saves some wear on the batteries, for whatever that's worth.

interesting.
Can you confirm that Tesla draws the power it needs from the grid and not from the batteries when plugged in? or... does Tesla always draws power from the battery and the grid just charges the battery.
it makes a great difference. I haven't found any indication for any of those theories online. I would greatly appreciate it if you can point me to such

 

[razh]

This means you can pre-heat or pre-cool the car without impacting range if it's plugged in at the time, which is really nice. Also saves some wear on the batteries, for whatever that's worth.

To clarify this, the car will pull as much as it can from the charge point to condition the cabin, but if the charge point does not provide enough current to satisfy demand, it will start to pull from the battery.

I see this often when on a 120-volt plug at a friend's place in the winter. It will lose range when heating even when plugged in, going from -4f (-20c) to 68f (20c)

 

[Rocky_H]

interesting.
Can you confirm that Tesla draws the power it needs from the grid and not from the batteries when plugged in? or... does Tesla always draws power from the battery and the grid just charges the battery.
it makes a great difference. I haven't found any indication for any of those theories online. I would greatly appreciate it if you can point me to such

Yes, that has been tested and measured directly from people's charging circuits. People can turn the heating up and down (while plugged in), and the amount of amps going through the circuit increases and decreases while the car is still showing no charging happening.

 

[TsRocket]

Have left mine as long as two months in my garage, plugged in. All was fine.

And here we are 2021, left car plugged in garage as long as 6 months. Leave the drivers window open, as car goes DEEP asleep. Not sure about the new ones, new S coming. Just to be safe, i,ll leave the window open.

 

[brucet999]

And here we are 2021, left car plugged in garage as long as 6 months. Leave the drivers window open, as car goes DEEP asleep. Not sure about the new ones, new S coming. Just to be safe, i,ll leave the window open.

I don't get it. Why leave the driver's window open?