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Scheduled preconditioning really helps

pshifrin

Member
Mar 8, 2021
60
44
Westchester County, NY
I drive my son to school early in the morning. Until this week, he was hybrid, 2 days per week in-person so a few minutes before, if I could remember, I’d preheat from the app. Now that he’s back 5 days a week, I set the scheduled departure in the car for 7:15am. With similar temperature conditions and highway speeds, I was using about 10% of the battery round trip and with the schedule departure method only 5%!

p.s. the car is plugged in overnight but outside, I have an outdoor 240 charger but no garage :(
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,018
6,942
Boise, ID
With similar temperature conditions and highway speeds, I was using about 10% of the battery round trip and with the schedule departure method only 5%!
The title of your thread says "Preconditioning really helps!" but you realize this isn't saving any energy, right? You seem really excited about this as if you think this is using less energy, but it isn't. All of the energy is still being used, but it's just using more of it directly from the wall at your house FIRST before you leave, and is actually probably using more than it needs to that way, so this actually wastes some extra energy.
 

jcanoe

Active Member
Oct 2, 2020
1,579
1,603
Maryland
A benefit of preconditioning the Tesla in colder temperatures is that the battery pack will be warmed. The impact of the colder temperature on regenerative braking is minimized. If you mostly charge at work or at a free to use public charging station you are not directly paying for the energy used to precondition the Tesla or for driving.
 

pshifrin

Member
Mar 8, 2021
60
44
Westchester County, NY
The title of your thread says "Preconditioning really helps!" but you realize this isn't saving any energy, right? You seem really excited about this as if you think this is using less energy, but it isn't. All of the energy is still being used, but it's just using more of it directly from the wall at your house FIRST before you leave, and is actually probably using more than it needs to that way, so this actually wastes some extra energy.
You are correct, I didn't account for that, my analysis was simply from the car driving efficiency standpoint. However, I'm fortunate to not be paying directly for almost all of my charging right now.
 
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pt19713

Member
Feb 5, 2020
791
963
Delaware
The title of your thread says "Preconditioning really helps!" but you realize this isn't saving any energy, right? You seem really excited about this as if you think this is using less energy, but it isn't. All of the energy is still being used, but it's just using more of it directly from the wall at your house FIRST before you leave, and is actually probably using more than it needs to that way, so this actually wastes some extra energy.
Yes and no. If you time both the charging of the battery and heating up the cabin, you can yield about 10% net efficiency assuming the drive is longer than a10 miles one way. You're correct in that the energy used and the breakeven point needed to get back that energy can be high. If the car is sat idle and you precondition from the app and not charging, 15 minutes will take about 2 kWh of energy. For me, I need to drive 40 miles to get that back (comparing the efficiency of a battery pack that's 40 deg F versus one that is 65 deg F). But, if you time the charging within 1-2 hours before leaving, there really isn't much wasted energy.

For longer trips, the preconditioning is going to pay off. Bjorn tested 20% higher efficiency with a preconditioned battery on a Model 3. My tests show 15% on a Model Y.
 

ChrisMPK

Member
May 15, 2018
71
71
Monterey Park, CA
I think you're missing the point. By preconditioning, you will start and end your trip with a higher SOC. Also, the car will be easier to drive (regen at full) and more comfortable (cabin preheated). Also, if you are on a TOU plan, you are more likely to be using low cost energy assuming you have entered the appropriate info into the scheduled departure settings.
 

jcanoe

Active Member
Oct 2, 2020
1,579
1,603
Maryland
I preconditioned the hell out of my Model Y this winter and never got full regen back. Usually at least 5 dots remained after preconditioning. Still quite usable and much better than the alternative, i.e. not preconditioning and having no discernible regen at all.
 
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juicevibes

Member
Feb 5, 2021
29
6
California
I think you're missing the point. By preconditioning, you will start and end your trip with a higher SOC. Also, the car will be easier to drive (regen at full) and more comfortable (cabin preheated). Also, if you are on a TOU plan, you are more likely to be using low cost energy assuming you have entered the appropriate info into the scheduled departure settings.
Sorry what is SOC and TOU? I'm a newbie here and trying to learn more about this car. Thanks!
 

ACofNY

Member
Aug 25, 2019
52
17
Long Island, NY
In my case where I only have 110v 20 amp charging at home, it does not work out. It uses and drains the battery to precondition the car. With delayed charging, when I get in the car at 7 am, it says it will complete charging at 10 AM. I find when it is cold out, I drive home and charge right away since the battery is warm. Also, since my M3 does not have a heat pump, i rather take off without heat on and let the driving heat everything up. After a while, then I turn the cabin heat. i find that is the most efficient way, but I do lose regen for some time. Why am I doing this? My daily trip is very short, and I lose over 50 percent efficiency in the winter If I drive as I would normally with heat. And it takes quite a bit of time to charge especially if I try the precondition/delay charging. Tesla algorithm does not account for 110v charging.
 
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jcanoe

Active Member
Oct 2, 2020
1,579
1,603
Maryland
In my case where I only have 110v 20 amp charging at home, it does not work out. It uses and drains the battery to precondition the car. With delayed charging, when I get in the car at 7 am, it says it will complete charging at 10 AM. I find when it is cold out, I drive home and charge right away since the battery is warm. Also, since my M3 does not have a heat pump, i rather take off without heat on and let the driving heat everything up. After a while, then I turn the cabin heat. i find that is the most efficient way, but I do lose regen for some time. Why am I doing this? My daily trip is very short, and I lose over 50 percent efficiency in the winter If I drive as I would normally with heat. And it takes quite a bit of time to charge especially if I try the precondition/delay charging. Tesla algorithm does not account for 110v charging.
If there is only the one 20A receptacle on the circuit an electrician may be able to rewire this for 240V using the existing wiring. There would need to be space in your home's electrical service panel for a 20A double pole circuit breaker. The power would be doubled, you charging time halved.
 
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flyhighboi20

Member
Sep 22, 2019
27
12
Michigan
I think you're missing the point. By preconditioning, you will start and end your trip with a higher SOC. Also, the car will be easier to drive (regen at full) and more comfortable (cabin preheated). Also, if you are on a TOU plan, you are more likely to be using low cost energy assuming you have entered the appropriate info into the scheduled departure settings.
My utility company sucks for TOU, on my plan from Oct-May its 1 whole cent difference per KWH lol. I called them and asked if this plan was a joke, they told me between Jun and Sept its 5 cents difference. So I don't worry about when I plug in anymore. I have seen other people utility bills that it makes a huge difference, just 30 miles south of me with a different utility company the difference was massive.
 

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