Home Charging and Preconditioning Questions

[widget_pilot]

Posted this on a popular Tesla subreddit 3 days ago and nobody ever responded. Quite helpful they are...

Anyways, today is 1 week with my new M3LR. Still love it and make any excuse I can to go drive somewhere. Put 500 miles so far just around town, but first road trip is tomorrow.

I have a few questions I can't seem to find an answer to.

1. I have a 14-50 outlet and keep the Tesla (don't use third party apps for charging) set at 75% battery. However, every time I have gotten back in, it's always at 74%. Not a big deal, I am just OCD and am genuinely curious. I have read of people using third party apps to set charge limits and this might happen, but I am setting the limit straight on the Tesla.
2. I live in Cincinnati, so I typically condition the battery in the morning when it is cold and still plugged in (either by a scheduled departure or just turning on the climate control 15-20 minutes before I leave). However, the battery is always at 73% when I get in, or will be at 74% but drop to 73% as I am pulling out of my driveway. Is this because the heater is pulling more energy that the charger can replenish it? If I precondition for say an hour, will it drop even more?

Thanks!

 

[bobby g]

So you're picking up your completely full (set amount) glass of water. From the table to your mouth some of it is spilled. It's no longer 75% but now 74% full. Electrons are so like water!

Sorry, couldn't resist. You're doing it right and it often seems weird - enjoy your car.

 

[toolman335]

Posted this on a popular Tesla subreddit 3 days ago and nobody ever responded. Quite helpful they are...

Anyways, today is 1 week with my new M3LR. Still love it and make any excuse I can to go drive somewhere. Put 500 miles so far just around town, but first road trip is tomorrow.

I have a few questions I can't seem to find an answer to.

1. I have a 14-50 outlet and keep the Tesla (don't use third party apps for charging) set at 75% battery. However, every time I have gotten back in, it's always at 74%. Not a big deal, I am just OCD and am genuinely curious. I have read of people using third party apps to set charge limits and this might happen, but I am setting the limit straight on the Tesla.
2. I live in Cincinnati, so I typically condition the battery in the morning when it is cold and still plugged in (either by a scheduled departure or just turning on the climate control 15-20 minutes before I leave). However, the battery is always at 73% when I get in, or will be at 74% but drop to 73% as I am pulling out of my driveway. Is this because the heater is pulling more energy that the charger can replenish it? If I precondition for say an hour, will it drop even more?

Thanks!

If the car is cold and you crank on the heat in the morning it will suck energy out of it at a pretty high rate. That being said, I'm a 2019 M3 owner and I don't have the heat pump. What you have is more efficient with heat than mine, but I don't know exactly how that works upon startup.

When you charge to 75 do you check the power immediately upon completion? Or do you want a while? The car will stop the moment it hits 75, but it's barely at 75. A little vampire drain and it will drop to 74.

 

[GtiMart]

After charging, the estimate of pack capacity and fullness might change a bit. It seems especially true in cold climates. Here, I set to 75% and it might indicate 77% the next morning when my car's parked outside. This is not because the charge augmented, it's because the car thinks the overall battery capacity is a bit lower, and it contains the same energy so in proportion it seems a bit fuller. All that to say that battery total capacity and state of charge are not a perfect measure, you will need to get over your OCD.
Your 14-50 plug and mobile charger supports 32A at 240V, that is ~7.5kW. When you start the interior conditioning, the car might temporarily consume more than that because it also heats the battery when it's cold enough outside. The car might only start charging when it goes down to 74%, and the charger might not quite provide enough power so your SOC might go down a bit.

 

[toolman335]

After charging, the estimate of pack capacity and fullness might change a bit. It seems especially true in cold climates. Here, I set to 75% and it might indicate 77% the next morning when my car's parked outside. This is not because the charge augmented, it's because the car thinks the overall battery capacity is a bit lower, and it contains the same energy so in proportion it seems a bit fuller. All that to say that battery total capacity and state of charge are not a perfect measure, you will need to get over your OCD.
Your 14-50 plug and mobile charger supports 32A at 240V, that is ~7.5kW. When you start the interior conditioning, the car might temporarily consume more than that because it also heats the battery when it's cold enough outside. The car might only start charging when it goes down to 74%, and the charger might not quite provide enough power so your SOC might go down a bit.

Good point there are times when the car shows it being above the percentage too.

 

[Harriscott]

Since you mention road trip: If yours will need supercharging stop(s) I recommend leaving with 100%, since that is gentler on the battery (if you don't stay at 100 for a long time). And it saves a few minutes at the first supercharger. I usually use the app to start charging to 100 a few hours before departure time.

 

[toolman335]

Since you mention road trip: If yours will need supercharging stop(s) I recommend leaving with 100%, since that is gentler on the battery (if you don't stay at 100 for a long time). And it saves a few minutes at the first supercharger. I usually use the app to start charging to 100 a few hours before departure time.

Yes I do that as well. Plan to hit 100 right before you leave so no damage is done to the battery. Waiting to get to 100 at a supercharger is a waste of time and money.

 

[widget_pilot]

Yes I do that as well. Plan to hit 100 right before you leave so no damage is done to the battery. Waiting to get to 100 at a supercharger is a waste of time and money.

Is there a way to tell the car to have it charged to 100% by X time? So it hits 100 right at that time. It seems like I can't figure out a way in the car or the app. There is the scheduled departure time and scheduled charging, but they don't seem to correlate to one another.

 

[Harriscott]

what I do: in the app slide to 100 and see how long that would take. Suppose 3 hours. Then I used scheduled charging to start 3 hours before departure. Or maybe 3.5 hours if I really want to reach 100. But I'm happy with 95+ and 95 means less "no regen" surprise.

Oh! After departure set the limit back to 90 (or less, but maybe not for road trip).

Perhaps scheduled departure would do all this, but have never tried it. Would be handy but fewer gamification opportunities.

 

[Flybyglass]

Cabin temperature will be achieved before battery temperature. If the charge scale/cable and are amber and there are heat symbols next to the battery in the app the battery is still heating. A s now flake will be present the car. Tesla in the cold weather section suggests 30-45 minutes to preheat battery in cold weather.