Time of Use and Cold Weather

[PagodaY]

I have Time of Use electric billing with high peak time between 2pm and 7pm.
I have the App set for scheduled charge at 7:15pm

However, most of my car use occurs early in the day so when I return home, the car sits not charging until 7:15pm.
In the warmer months, that's not a problem, but now that the weather has turned colder, I'd really like to have the car charge when the car returns from use and the battery is warm. Waiting until 7:15 allows the battery to cool down enough that when the 7:15pm charge starts, I assume the car is using energy to warm the battery in addition to charging the battery.

So, my question is, is there a setting in the app that allows the car to charge at any time other than the high peak time frame? ie - charge when I get home, and then, if the car has not reached it's set SOC (60%), stop charging at 2pm and resume at 7:15PM?

2023 LRMY, unheated car port, 220V30A charging.

 

[jjrandorin]

I believe if you have a generation 3 wall connector there may be some setting in there to accomplish this. There is not one in the regular tesla app related to car charging, though.

This thread here is the same basic discussion:

Car does not pause charging when peak hour is reached

With software 2023.44.30.5.1 (and some prior versions), if the car is set to have a peak hour start and scheduled departure time far beyond the peak hour start, it does not pause charging at the peak hour start if plugged in before the peak hour start. For example: Peak hour start at 16:00...

teslamotorsclub.com

 

[ucmndd]

I assume the car is using energy to warm the battery in addition to charging the battery.

Unless the pack cools to near or below freezing in the time between it being parked and the time charging starts (unlikely unless it’s EXTREMELY cold, a thousand pound battery has a lot of thermal mass) I doubt this is the case.

 

[ATPMSD]

If you have a wall connector you can add it to the Tesla app, you can then set an allowable window. Much better approach:

https://www.tesla.com/support/charging/wall-connector/tesla-app

 

[PagodaY]

Interesting observation on the mass of the battery vs the cooling. I hadn't considered that, but I would expect that the battery. over the course of 5 hours (2pm-7pm), would cool off, especially when it's cold (below 32F), hence the need to reheat the battery for charging.

I'm guessing that there's no place I can go to to determine the actual temp of the battery?

ATPMSD - I don't have a Tesla wall connector, just a 30A 220V outlet that I use, so that option is not open to me.

 

[jmaddr]

Doesn’t the app show that it’s heating the battery with L2 the way it does when you are in a supercharger? Check the app at 19:17 or so and see if it is indeed heating.

See the discussion here:

Battery Warming Icon in New App

Are any of you in a cold enough climate to have your battery start warming with cabin heating yet? Any idea where the battery warming indicator shows up in the app? Any idea of what temperature it needs to be at before it does warm?

teslamotorsclub.com

I’m in FL so in only a very few instances would it heat for L2 charging, so I can’t check. And to “override” the charging schedule, just open the app and press “start charging”. If you want it more permanent disable the scheduled timing for the season. If you want something more if-then-else then the gen 3 in the app or third party apps offer some level of customization. Stats on Apple’s App Store offers some of this.

 

[ATPMSD]

@PagodaY

Have you considered using Scheduled Departure instead of Scheduled Charge? If you set 7 AM, for example, the car will start to charge at a time to reach your desired SOC at 7 am. Given your peak ends at 7 pm, in this example, this gives you a 12-hour charge window. Note that when you plug in the car it will immediately start to charge for a short period to determine the available charge rate and then stop until it needs to start to meet the departure time.

Note also scheduled charge can be easily confused if you are using any 3rd party apps with the car. Good luck!

 

[ucmndd]

@PagodaY

Have you considered using Scheduled Departure instead of Scheduled Charge? If you set 7 AM, for example, the car will start to charge at a time to reach your desired SOC at 7 am. Given your peak ends at 7 pm, in this example, this gives you a 12-hour charge window

OP appears to be concerned that charging this way will result in significant wasted energy to heat the battery before charging.

As I said upthread, I’m pretty skeptical this would be the case. The car does not heat/precondition the battery for L2 charging anywhere near as aggressively as it does for supercharging. If the cells are above freezing, it’s pretty much game on.

 

[fhteagle]

Home Assistant would make automating this pretty easy.

 

[PagodaY]

I do use scheduled departure when planning trips and it works very nicely. But we're not on that regular a schedule (retired), so it's only useful on the occasional road trip.

Your suggestions about using a 3rd party app to regulate the time of charging reminded me that TeslaFi has this ability. I used it early on when the scheduled departure/charging section of the Tesla App was pretty funky (back in 2020). I revisited TeslaFi yesterday and found I can turn off charging at 2pm and turn on charging at 7pm, possibly solving the problem of arriving back home and charging with a cold battery at 7pm.

I like the idea of checking the app to see if the battery heating is active at 7:05. Sounds like I might be over thinking this issue!

Home Assistant? I'm currently using a VeraPlus for home control and am on the lookout for a replacement. But that's a different discussion.

Thanks everyone and have a Happy New Year!

 

[ATPMSD]

I do use scheduled departure when planning trips and it works very nicely. But we're not on that regular a schedule (retired), so it's only useful on the occasional road trip.

It all depends on the problem you want to solve. Scheduled Departure has two settings, you can use either of them or both:

If you choose “Off-Peak Charge” this is the time the car will be fully charged and ready to go.

The other option is “Precondition” which warms the car and battery. It can be set to a seperate time and days. This is the one that is pointless for someone who does not use their car on a daily basis

So then, if you enable Off-Peak and leave Precondition disabled, your car will be charged and ready to go each morning, whether you use it or not. This, I suggest, is better than working with 3rd party apps.

BTW, the verbiage for off-peak is confusing! The “Off-Peak End Time” is when you want the car to be ready to go, say 7 am.

 

[GtiMart]

There are a couple of ways to see the battery temperature. One of them is to get a cable that adds an OBD2 port, buy a good OBD2 dongle and use ScanMyTesla. Another option is to buy the S3XY buttons (which includes that cable), you can see the battery temperature in their application / dashboard.
If you had that you would see that: 1. the car only heats the battery a few degrees over freezing when charging on AC and 2. a big battery doesn't cool off that fast, even outside under freezing. It depends what temperature it was when you parked it after driving as well...

 

[gtae07]

BTW, the verbiage for off-peak is confusing! The “Off-Peak End Time” is when you want the car to be ready to go, say 7 am.

Actually it's more nuanced than that...

If you are on the departure page, there's a departure time and an off peak end time. Assuming you're charging overnight into morning, it works like this...

The car will finish charging at/just before the earlier of either your selected departure time, or the off-peak end time (at least assuming you have "off peak charge" enabled). My off-peak time ends at 0700 so that's what I leave it set at all the time, and I only change the departure time as required. Six days a week, that time is more like 0430 or so; on Sunday it's 0900. The car is always done charging at the earlier of the two times.

If you have "precondition" set on, it will also heat/cool the car for you and tends to hit that about 10-15 minutes prior to the time you selected. I therefore usually choose a time 15 minutes later than my actual departure, unless I expect frost (in which case I select my actual departure time, to give it time to melt said frost).

 

[PagodaY]

Thanks for the explanation, that saved me getting the dongle and determining that I was chasing gossamer windmills.

It was my understanding that the "precondition" setting on the Departure Time option would also precondition (warm) the battery to optimal driving temp, in addition to warming the cabin, when needed.

 

[gtae07]

It was my understanding that the "precondition" setting on the Departure Time option would also precondition (warm) the battery to optimal driving temp, in addition to warming the cabin, when needed.

I believe it does that as well. I just don't usually think about heating--cooling (and dehumidifying) tends to be more on my mind down here in the deep coastal south.

 

[ATPMSD]

It was my understanding that the "precondition" setting on the Departure Time option would also precondition (warm) the battery to optimal driving temp, in addition to warming the cabin, when needed.

Yes but:

1. If the battery is cold you will be unable to get full power from the car until it warms. However, unless you plan to floor it, this is not an issue.
2. The second issue is Reg braking is limited. But the car now has a feature that automatically applies the brakes in place of regen breaking when the battery is cold. Just ensure it is enabled: Controls > Pedals & Steering > Apply Brakes When Regenerative Braking Is Limited

Based on these facts I see no reason for preconditioning, except to warm or cool the car. In my case, I never use it and simply turn on the HVAC from the app about 5-minutes before I head out the door and find the temperature to then be fine.

 

[Calliope]

Another option is to set charging to start some time in the middle of the night........My TOU peak period ends at 9 pm, but my car doesn't start charging until 3 am. It takes usually 2-3.5 hours to charge back up to 80%, but it's still ready for me to leave for work the next morning. Unless I have plans to take it out in the evening after dinner, I have no reason not to charge it overnight; if I do have plans I can always override the scheduling with "Start Charging".