Charging Status in Tesla App

[CaliM3Hi]

Just took delivery of Model 3 Standard and started charging at home with UMC.
With my phone's Bluetooth turned off, and the car's Wi-Fi turned off, the Tesla App is giving live charging status.
Is the car constantly using its cell signal to transmit charging stats to the Internet for the App to pick up?

 

[EVRider-FL]

Yes, the car transmits charging status as long as it can reach the internet by any means. Bluetooth is not used for that or most other app features, it’s generally just used for opening the car (phone key) and pairing your phone for calls and media streaming.

 

[E90alex]

Yes, the car is constantly connected via cellular (as long as there’s signal obviously).

 

[CaliM3Hi]

Thanks for the confirmation. Would it use less energy if the car was connected via Wi-Fi?
I only ask because I charge a home w/ 110v and only get a little over 1 mi/hr. Don't know if the constant cellular connection uses much more energy than Wi-Fi.

 

[PCMc]

I don't think you'll find any appreciable difference in charging rate if the car is connected via wifi vs. cellular. The key issue with slow charging is charging on a standard 110v outlet is only about 1 kW, and if the car needs any energy to be running HVAC to precondition the car, or thermal management for the battery pack temp, even less is actually going into the pack.

I will take a slight exception to the comment that the car is continually broadcasting charging status back via cellular to Tesla servers. My understanding is that the communication to the app is more on demand, so a pull from the app, not a push from the car. So if while charging you shut the app on your phone off, there is no "pull" for charging info, so no need for car to be broadcasting that info to Tesla server and then to your phone. I've been running my own data logger using the Tesla API and if I don't forcably wake the car, then I don't receive live data coming back.

So if you do have wifi access available at your home, I'd go ahead and connect it just because that will better support you getting software updates downloaded when available. But I would not expect an appreciable difference in charging rate of your car.

 

[CaliM3Hi]

Great! Thanks for the reply. The Tesla associate told me to leave the app running and not to close it, so I assumed there would be constant communication. If communication only happens when I bring focus to the app, then that's a different story.

 

[PCMc]

Great! Thanks for the reply. The Tesla associate told me to leave the app running and not to close it, so I assumed there would be constant communication. If communication only happens when I bring focus to the app, then that's a different story.

One of the reasons to leave the app running is if you have a newer car that uses your phone as key. You get the best performance for it automatically recognizing you when you walk up if the app is running in the background on your phone. Otherwise, you'll likely need to pull out your phone, open the app before it recognizes your phone as a key.

Another way to think about your charging situation is think of the power your cell phone uses to charge. Your phone charger at home is likely only a 10-20 watt charging device. Your UMC, on a 110V, 15 amp circuit, is continuously pulling around 1 kW, or 1,000 watts. So about a 1000 to 1 difference. Kind of like the difference in power draw of your full size 1200 watt microwave running at full power versus your cellphone.

Now get yourself a 40 amp, 240V setup, and you'll be talking roughly another factor of 10 again, which is why most people who can install a home 240V charging setup will.

Enjoy your car.

 

[thimel]

1 mi/hr charging rate on 120 V is rather slow. It should be more like 3 or 4.

 

[EVRider-FL]

I will take a slight exception to the comment that the car is continually broadcasting charging status back via cellular to Tesla servers. My understanding is that the communication to the app is more on demand, so a pull from the app, not a push from the car. So if while charging you shut the app on your phone off, there is no "pull" for charging info, so no need for car to be broadcasting that info to Tesla server and then to your phone. I've been running my own data logger using the Tesla API and if I don't forcably wake the car, then I don't receive live data coming back.

I’d like to learn more about this. Are you logging data being sent from the car to the Tesla server? While I agree that it isn’t necessary for the car to broadcast continuously (and I don’t know if it does), I could see where the car might broadcast the charging status at certain intervals, so that an app could get updated data from the server rather than the car. Not saying that’s how it works, just wondering.

 

[brkaus]

I’d like to learn more about this. Are you logging data being sent from the car to the Tesla server? While I agree that it isn’t necessary for the car to broadcast continuously (and I don’t know if it does), I could see where the car might broadcast the charging status at certain intervals, so that an app could get updated data from the server rather than the car. Not saying that’s how it works, just wondering.

Teslafi is a cloud based data logger that I use. They all work about the same way.

The app polls the car at some interval (think 20 seconds or so). If the logger decides the car is idle, it will stop polling for 10 minutes (or so). That allows the car to fall asleep (if it’s tired). Then the polling starts again. If the car is sleeping, the standard polling does not wake it up. A special call has to be made to wake the car once sleeping.

 

[CaliM3Hi]

One of the reasons to leave the app running is if you have a newer car that uses your phone as key. You get the best performance for it automatically recognizing you when you walk up if the app is running in the background on your phone. Otherwise, you'll likely need to pull out your phone, open the app before it recognizes your phone as a key.

Another way to think about your charging situation is think of the power your cell phone uses to charge. Your phone charger at home is likely only a 10-20 watt charging device. Your UMC, on a 110V, 15 amp circuit, is continuously pulling around 1 kW, or 1,000 watts. So about a 1000 to 1 difference. Kind of like the difference in power draw of your full size 1200 watt microwave running at full power versus your cellphone.

Now get yourself a 40 amp, 240V setup, and you'll be talking roughly another factor of 10 again, which is why most people who can install a home 240V charging setup will.

Enjoy your car.

Thanks very much for the guidance!

 

[CaliM3Hi]

1 mi/hr charging rate on 120 V is rather slow. It should be more like 3 or 4.

The app says it's 1kW, +0kWh, 12/12A, 110V. The 1mi/hr is my approximation. This is the first time charging, and it was ~60% charged when I got it home.

 

[BitJam]

Congrats on your new car!

I leave the app running on my phone all the time so I can use the phone as a key. I doubt the app is updating any information in the background because there is always a significant lag in the information on the screen when I open the app. Then when information does show up it is usually from the last time I opened the app and is therefore out of date at first.

I often use the app for starting the climate control. There is a lag before the climate control seems to start and a longer lag before it properly reports the interior temperature.

Generally, opening up the app will wake up the car which takes some energy because it won't go back to sleep instantly. The car being awake consumes about 100 to 200 watts. IMO you won't notice any extra energy consumption from a wifi or cell connection. I think the car has to be awake when it charges and this 100 to 200 watts is one of the reasons why level 1 charging is less efficient.

In cold weather, the car needs to warm up the battery before it charges. If it's cold enough then you may not be able to charge the car with level 1 because it doesn't get enough energy to heat the battery.

Speaking of heat, the car will often make strange noises when you don't expect it to, such as an hour or two after you last used it. This is usually because it's moving heat around in order to save energy. The Tesla engineers were fanatical about efficiency and saving energy. I added some extra sound insulation to the hood of my frunk and stopped worrying about the noises.

 

[PCMc]

I’d like to learn more about this. Are you logging data being sent from the car to the Tesla server? While I agree that it isn’t necessary for the car to broadcast continuously (and I don’t know if it does), I could see where the car might broadcast the charging status at certain intervals, so that an app could get updated data from the server rather than the car. Not saying that’s how it works, just wondering.

You can find a lot of documentation out there on the Tesla API which a group of enthusiasts were able to create via backward engineering of the broadcasts. Here's the main reference if you'd like to review it. Introduction | Tesla JSON API (Unofficial)

It's all based upon using REST api call which go through Tesla server to the car with data returned from the car through Tesla server to the logging system. In my case, I've used this to write my own python code which I run on my home laptop to pull data from my car.

The charging stats which are the basis of what's shown in the app, such as voltage, amps, kW, rate of charging (in miles/hr) miles added during the charging session, time to completion are all included in a message broadcast back from the car. To get data I need to have both a working internet connection from my laptop to Tesla server as well as an internet connection (cellular or wifi) from Tesla server to my car.
As stated by others, there is a specific command to "wake" the car as it will go to sleep if nothing is pinging it. I actually see cases where Tesla server will respond to me (such as when I need to renew my access token), but the car is asleep and is not responding to message request from Tesla's server.

I can't say for certainty that the car does not send data to the server as defined streaming intervals when it's charging, but all the API interface for that communication implies it a data pull from the server, or in the case of my logger, a get request to the server that then pulls from the car. As others have correctly pointed out, reason you see such a delay on data updating in the app after you've left it closed for awhile is because the car is asleep and the app is needing to issue an intentional "wake" command.

 

[EVRider-FL]

Teslafi is a cloud based data logger that I use. They all work about the same way.

The app polls the car at some interval (think 20 seconds or so). If the logger decides the car is idle, it will stop polling for 10 minutes (or so). That allows the car to fall asleep (if it’s tired). Then the polling starts again. If the car is sleeping, the standard polling does not wake it up. A special call has to be made to wake the car once sleeping.

I also use TeslaFi, but I thought you might have been talking about something else. I’m also familiar with the Tesla API that @PCMc mentioned in their reply. Thank you both for your responses.

 

[Occhis]

Charging at 120 volts @ 12 amps is very inefficient. The car uses 400 watts to run the charging hardware, so you are drawing 1440 watts of power (120v*12A) but only utilizing 1040 watts to charge the battery. Roughly just 70% efficiency.
Using a 240v at 32A, 7680 watts, charging efficiency goes up to 95%
So charging at 120v is much more expensive.

 

[CaliM3Hi]

Charging at 120 volts @ 12 amps is very inefficient. The car uses 400 watts to run the charging hardware, so you are drawing 1440 watts of power (120v*12A) but only utilizing 1040 watts to charge the battery. Roughly just 70% efficiency.
Using a 240v at 32A, 7680 watts, charging efficiency goes up to 95%
So charging at 120v is much more expensive.

Thanks very much for the breakdown. After a few more charging cycles, I'll be able to see what the break-even point in price will be to charge from a more expensive rate/kWh at a supercharging station.