Preconditioning and Charging the Car

lphe · Mar 21, 2015

I have searched through the forums, but can't seem to find the information about preconditioning and charging that I am looking for. The salesperson I spoke with mentioned that there was a way to specify when you want the car to charge, i.e. during off peak hours when electric rates are low. And also I would be able to schedule times when I would like the car to be preconditioned for my daily commutes to and from work. But I can't seem to find any information on this anywhere. Are these features available?

For charging, I would like the car to only draw power from my outlet during off peak hours (9:00 pm to 7:00 am when the electric rate is low: $0.0585/kWh). During peak hours (4:00 pm to 9:00 pm when rates are high: $0.38/kWh), it should under no circumstances draw any electricity at all. I would like to be able to plug the car in (I have a level 2 EVSE) when I come home from work at 5:00 pm and have the car not draw any power until 9:00 pm. I don't want to have to wake up in the middle of the night just to plug the car in to avoid charging during peak hours.

I go to work at 5:30 am each morning. When it is below 0 F, I want to start out in a warm car. The car should provide me with a way to schedule preconditioning so the car will be ready for me at 5:30 am each morning and the interior cabin temperature is 72 F, and the battery has also been warmed.

I look at screenshots of the Android app and I don't see these features.

svp6 · Mar 21, 2015

You can set up at what time charging starts under charging menu in the car. You cannot set when charging ends.
There is smart preconditioning option which is in beta. No way to set the car to preheat at a precise time each day, only manual from the iPhone app - not sure about Android

eye.surgeon · Mar 21, 2015

Tesla has made the odd choice of having the car learn your schedule rather that you programming your schedule. It's inefficient in my opinion. It's like having an alarm clock that learns when you want to wake up. I just want to tell it when I want to wake up, I can't rely on it making an intelligent guess. They've made it unnecessarily complicated. I turned preconditioning off after a couple times of walking into my garage to find my car warming up when I wasn't going anywhere. I don't really need to precondition anyways as my garage is almost never below 50 degrees.

lphe · Mar 21, 2015

Thank you for your replies. I read the manual as follows and couldn't figure out what they were talking about:

Smart Preconditioning: If on, Model S predicts your driving schedule and adjusts the temperature of the cabin and the Battery so the vehicle is comfortable and ready to drive. It may take some time for Model S to learn your driving habits.

I don't see anyway for the car to predict my driving habits--it can't read my mind. I have to tell it what I plan to do. I'm not always that predictable from one week to the next.

When it is below 0 F, it will probably require many kWh of electricity to warm the car. If it preconditions the car unnecessarily, that is going to waste a lot of electricity. If I am going to be that wasteful, there is little point in signing up for the EV rate plan from the electric company to save on electric costs.

Cyclone · Mar 21, 2015

The rep I test drove with earlier this week said that Smart Preconditioning also takes into account calendar events. So I would suggest syncing a calendar with your Tesla and setting a 5:30 appt for going to work. Hopefully that will help the Smart Preconditioning to warm up your car for your departure. That said, smart preconditioning is far too complicated (IMO) with its current setup and some people have seen it turn on at odd times. I would suggest paying close attention to it at first to see if it learns your schedule properly. Hopefully Tesla will at least expand on this so the car can tell you when it thinks it should precondition and you have the option of telling it is is wrong!

lphe · Mar 21, 2015

Rather than using an Android application, is there a web site I can log into to perform the same functions as on the app?

Also, if I use the Android application to precondition the car, how far in advance do I need to notify the car I want the cabin temperature to be 72 F? I assume it will start warming the cabin immediately. If I don't tell it soon enough ahead of time, it won't be warm. If I tell it too soon ahead, I am wasting electricity.

Cyclone · Mar 21, 2015

You can use VisibleTesla on your computer to do much of the same functions (and more), but alas, Tesla has made changes recently that many newer cars cannot use the software.

lphe · Mar 21, 2015

The following is from the Tesla web site:

Charge at Night Charging at night isn’t just convenient, it may be less expensive. Many utility companies offer Time of Use rate plans featuring prices that vary based on demand. At night, demand is lowest and prices drop. The Touchscreen lets you program a charging schedule to take advantage of these low rates. Plug in when you get home and Model S will begin charging automatically at the time you specify.

This implies that I should be able to set a charging schedule to take advantage of my EV rate plan. But I don't see how to do it.

dirkhh · Mar 21, 2015

When plugged in you can tell your car to schedule the charge at a later time. While we were charging both of our EVs at the same time (we no longer do that) I had my Tesla programmed to start charging at 1am - by that time the Leaf was either done already or so far in its taper that I no longer risked overloading my panel.

The "learning" preconditioning as implemented by Tesla is utterly useless unless you work an excessively regular 9-5 job. I leave my house at a different time every morning, this does nothing for me.

lphe · Mar 21, 2015

Telling the car to delay scheduling may work OK at night provided it finishes charging before peak hours the next day. But then, I would have to remember to unplug it during peak hours each day, use a timer, or reset the delay, if I plug it in during the day to charge and it has not finished before peak hours. In addition, the car could decide to start drawing power for some other reason during peak hours. There doesn't appear to be anyway to tell the car not to draw any electricity during peak hours (4 pm to 9 pm). I would have to use a timer. Tesla really should implement what they promised--the ability to provide a charging schedule to charge during off peak hours.

RichardL · Mar 21, 2015

When I first got mine, I set it to start charging at 12:05 am - just after the cheap time sets in. Now I simply plug in when I get home at it reliably charges when it's cheap. The worst case I have seen is it to finish at around 7 because it was almost empty when starting. It doesn't ever simply start drawing power at other times.

I never need the pre-conditioning. A couple of times I used the App to turn on the HVAC, which also does he battery.

Don't over worry- it is very simple to get the routine working.

Ugliest1 · Mar 21, 2015

lphe said:
This implies that I should be able to set a charging schedule to take advantage of my EV rate plan. But I don't see how to do it.

Touch the little battery symbol on the upper left of the main screen. The Charging screen pops up:

Move the Scheduled Charging slider to On, and a time clock will display. Simply set the start time you want your car to start charging (in the picture, mine is set to 3:30am). With a L2 charger you'll have to do some guessing initially what's the best time to start in order for your car to finish a little before you'll be ready to leave. And that of course will also depend on what's left on the battery when it starts charging. Some trial and error will get you to a pretty comfortable set of habits and times. The other thing you can do is just start it at 2:00am (example), then from your app turn on the heater 30 minutes before you'll be ready to go - that'll draw minimal power from the wall and preheat your cabin and warm the battery enough that you likely won't lose part of your regen braking (the dotted yellow line that appears when it's cold). If it's really cold you may have to preheat twice.

I don't have an answer for leaving the Model S plugged in during the day and hoping it won't use ANY electricity. I think Tesla has tried to build the software so that it protects the battery as much as possible, without anything having to be done by the owner (i.e., "just plug it in and forget it"). Personally, even at $.38/kwh, I'd rather have the Model S protect itself. On the other hand, if you unplug it during the day, the car will still protect itself anyway using battery power, which would then be recovered at 2:00am on the low rate.

GSP · Mar 21, 2015

I don't think Tesla has a option to prevent the car from using electricity during the peak rate period. However, I am pretty sure that EVSEs are available that can be programmed to not allow the car to draw power during set time periods. The Open EVSE kit can be certainly be programmed to do so, but it is a DIY project. One other option is to have a timer installed on the circuit to your HPWC or 14-50 outlet. I would probably do that if I had $0.38/kWh peak rates.

GSP

lphe · Mar 21, 2015

It is unacceptable to have the car charging during peak hours. If it should decide to charge during peak hours, it will consume about 10 kW of electricity for five hours, or 50 kWh. At $0.38/kWh that amounts to $19.00. If it does that very often, I am not going to save any fuel costs buying an EV. I might as well buy a conventional car that runs on gasoline.

Has anyone else used a timer to control charging of the car? Is it OK to plug the car in when the circuit is de-energized and then will it start charging properly later when the timer re-energizes the circuit?

ghost640 · Mar 21, 2015

lphe said:
It is unacceptable to have the car charging during peak hours. If it should decide to charge during peak hours, it will consume about 10 kW of electricity for five hours, or 50 kWh. At $0.38/kWh that amounts to $19.00. If it does that very often, I am not going to save any fuel costs buying an EV. I might as well buy a conventional car that runs on gasoline.

Has anyone else used a timer to control charging of the car? Is it OK to plug the car in when the circuit is de-energized and then will it start charging properly later when the timer re-energizes the circuit?

Yes, I do that all the time. Power comes on at 11:30, charging starts 11:35, works great.

martinwinlow · Mar 22, 2015

If the car can read events on its calendar why not just have a standard event called 'pre-condition Tesla' or something equally unequivocal? That would take all the wishy-washy-ness out of it, wouldn't it? Ideal for us shift-workers!

jerry33 · Mar 22, 2015

lphe said:
It is unacceptable to have the car charging during peak hours. If it should decide to charge during peak hours, it will consume about 10 kW of electricity for five hours, or 50 kWh. At $0.38/kWh that amounts to $19.00. If it does that very often, I am not going to save any fuel costs buying an EV. I might as well buy a conventional car that runs on gasoline.

Has anyone else used a timer to control charging of the car? Is it OK to plug the car in when the circuit is de-energized and then will it start charging properly later when the timer re-energizes the circuit?

1. There is a timer you can set for the start of the charge.

2. The car may be unplugged or plugged in at any time.

lphe · Mar 22, 2015

This is the scenario I am concerned with. I drive around in the morning and come home in the afternoon. I now want to charge the car until 4:00 pm, at which time peak hours begin, so I have enough range for trips later in the evening. There is no way to tell the car to stop charging at 4:00 pm. If I forget to unplug it, I am going to be very upset stuck with a large electric bill. In addition, smart preconditioning is unreliable. It may decide to start preconditioning the car during peak hours. I have no choice but to use a timer.

lphe · Mar 22, 2015

The following are my expectations for "Smart" preconditioning:

1. I should be able to look at the calendar (or have some other mechanism) to see all the preconditioning events that the car has scheduled for me or that I have explicitly scheduled.
2. The calendar event indicates the time I am leaving and the desired cabin temperature.
3. The car should figure out when to start preconditioning so that the desired cabin temperature is reached at the moment I wish to leave.
4. I should have the option of scheduling a series of recurring events, i.e. my morning commute to work.
5. I should have the ability to skip a scheduled event, e.g. I am not going to work today.
6. I should have the option to specify if preconditioning takes place only if the car is plugged in. In this case, the car will need to start charging the car early enough so that it will replace all the energy that will be consumed by preconditioning. I don't want preconditioning to decrease my range. In the winter, precondition can take several kWh of energy when temperatures are below 0 F.
7. I should be able to access a web site to look at my calendar and update it.

lphe · Mar 22, 2015

These are my expectations for "Smart" charging:

1. I should be able to specify electric rates for each hour of the day and each day of the week.
2. The car should under no circumstances use any electricity during peak hours.
3. The car should be able to figure out how to charge my car at the lowest cost.

Preconditioning and Charging the Car

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