Schedule charging to maximize battery heat in freezing weather

[Silicon Desert]

The cheapest time to charge is when your battery is already naturally warmed up from driving home on your commute.

Not necessarily. For people living in a very expensive electricity rate area and working a 9-5 job like my son, it is really expensive from the hours of 4pm to 9pm until the electric rates drop greatly. Best charging time for him is after 9 pm and by that time it will be cold again. So bottom line is I guess it really depends on where you live, how cold it is, and the electric rate cost at the time you want to charge.

 

[mswlogo]

Not necessarily. For people living in a very expensive electricity rate area and working a 9-5 job like my son, it is really expensive from the hours of 4pm to 9pm until the electric rates drop greatly. Best charging time for him is after 9 pm and by that time it will be cold again. So bottom line is I guess it really depends on where you live, how cold it is, and the electric rate cost at the time you want to charge.

I said that, you conveniently left that out of the quote.

It might be expensive just before he leaves for work as well. So yeah if you have off peak it would cool if it could finish charging just as off peak finished. Which could get tricky with pre heating. But it could learn it.

Also the OP didn’t mention that scenario either.

 

[Runebane]

The cheapest time to charge is when your battery is already naturally warmed up from driving home on your commute.

…

The goal isn’t max wh/mi on the car. It’s minimum total kWh on your electric meter/bill.

You end up paying the same either way. If you charge the car when you get home and it's warm, you charge more efficiently. But you lose on efficiency the next morning when you drive off. Either way you're going to pay more in the winter, either by warming the battery up to charge or by warming the battery up while driving. In Both cases the cold battery is going to get to it's ideal temperature and you're going to pay for it to warm up.

It would be very cool to have someone who has their charging station on a separate meter to do it both ways for a week and see if there's a difference and which is more ideal. My guess is they would be pretty close to equal.

 

[Silicon Desert]

I said that, you conveniently left that out of the quote.

It might be expensive just before he leaves for work as well. So yeah if you have off peak it would cool if it could finish charging just as off peak finished. Which could get tricky with pre heating. But it could learn it.

Also the OP didn’t mention that scenario either.

yea, I see that now. Somehow it didn't register when I first read it

 

[eCharcoal]

I wonder if we set the charging amperage lower in order to stretch the charging time would help. For instance, when I get home, it usually takes about 3 hours to charge (at 32 amp) the battery back to its original SOC. If I set the charge to start at 9pm, charging at 12 amp, charging would be done at around 5am. I should have a relatively warm battery pack by the time I leave home at 6am. Right?

 

[BerTX]

I haven't used it yet, but I'm sure the Dashboard for Tesla app allows you to set it to "start the charge at a time such that the battery is charge-complete at time X". The app is like $15, plus a few for the smart charging, for life.

Dashboard for Tesla can definitely do what is asked for in this thread. Be aware that it only works on Android phones, so the other half of users will need another solution. I don't use TeslaFi, but have seen people claim it can do this.

 

[Silicon Desert]

Dashboard for Tesla can definitely do what is asked for in this thread. Be aware that it only works on Android phones, so the other half of users will need another solution. I don't use TeslaFi, but have seen people claim it can do this.

Maybe you are thinking of something else. I have used TeslaFi for a year and don't know of any way that it has this feature. And there is no separate app for Teslafi.

Added.... people on the Teslafi forum have requested such a feature be added.

 

[BerTX]

Maybe you are thinking of something else. I have used TeslaFi for a year and don't know of any way that it has this feature. And there is no separate app for Teslafi.

Added.... people on the Teslafi forum have requested such a feature be added.

I have seen it stated many times. You might want to review the "Scheduling" feature of TeslaFi. Granted, it is not an "app", but it can be done, according to what I have read. As I said, I don't use it and those other users may be mistaken.

Available Controls

• Wake Up: Sends a wake up command to the vehicle. The API does not provide a response to this command so it will only be sent once.
• Flash Lights: Flashes the headlights of the vehicle.
• Honk Horn: Honk the horn of the vehicle.
• Lock Doors: Lock the doors of the vehicle.
• Unlock Doors: Unlock the doors of the vehicle.
• Start HVAC: Start the conditioning of the vehicle. Note: The HVAC will continue to run until it is stopped or the battery level reaches 20%.
• Stop HVAC: Stop the conditioning of the vehicle.
• Set HVAC Temperature: Set the temperature of the HVAC system.
• Start Charging: Starts charging.
• Stop Charging: Stops charging.
• Set Charge Limit: Set the charge limit percentage.

 

[Silicon Desert]

I have seen it stated many times. You might want to review the "Scheduling" feature of TeslaFi. Granted, it is not an "app", but it can be done, according to what I have read. As I said, I don't use it and those other users may be mistaken.

Thanks. I just checked it again and no such thing. And the fact that people request this feature on the forum leads me to think other people are confused assuming there really is such a feature. The "scheduling" feature is really just as way to inform users when charging is complete, not an actually way to schedule it. It only allows setting the charge level and do conditioning. It's mainly a reporting feature with several pieces of nice data.

 

[BerTX]

Thanks. I just checked it again and no such thing. And the fact that people request this feature on the forum leads me to think other people are confused assuming there really is such a feature. The "scheduling" feature is really just as way to inform users when charging is complete, not an actually way to do it. It only allows setting the charge level and do conditioning.

Okay, I'm going to bow out because I don't really know anything. I got the above directly from the TeslaFi website. I'm not going to go search for links to all the times it has been stated on TMC that it works. Maybe one of those users will chime in and you can discuss it with them. I use Dashboard for Tesla for this purpose, but it only works on Android devices.

 

[GPinzone]

I wrote a script to start the HVAC system at 4pm on a M-F if the car is at my job. I suppose I can come up with another script to calculate when it should be started and set that time, but that would mean I'm relying on my phone to wake up, wake the car up and start the charging at the calculated time. That's not an ideal way to do it. All the logic should be in the car's software, not a phone sending remote commands. I'm too nervous that something would go wrong and the car wouldn't charge at all.

 

[smatthew]

Maybe you are thinking of something else. I have used TeslaFi for a year and don't know of any way that it has this feature. And there is no separate app for Teslafi.

Added.... people on the Teslafi forum have requested such a feature be added.

I think you are mistaken. You can definitely set schedules for the items that BerTX listed.

Once you're logged into TeslaFi, Click on "Controls" and select "Schedules"

The above image shows all the tasks TeslaFi can schedule

 

[HostileHarry]

TeslaFi.com can do what you seek. I have both my Model 3 and X setup to begin charging and then end before we leave the house.

 

[Silicon Desert]

TeslaFi.com can do what you seek. I have both my Model 3 and X setup to begin charging and then end before we leave the house.

Ok folks, I think I see the disconnect here. While yes, it will allow you to create a specific start and stop time for charging, that is not the same as what I and others are talking about as a requested feature. TeslaFi currently DOES NOT calculate and dynamically start charging at a time which will get it to a requested charged level (like 95% or 100%) at a specific time. The folks on Teslafi asking for this feature are wanting the car to be at a given charge level at an approximate time when they are willing to leave. Thus, they want to say at X time, I want the car to be at X percent charge; now go figure out when charging needs to start in order to achieve that end. Yes, as some say, you can manually calculate that yourself and then manually schedule a start time, but the point of folks is they don't want to have to do it manually when it would be easy to do that from new software in the car on a product like TeslaFi.

It's not the same as setting a specific static start and stop time. I agree it can do that.

 

[Big Dog]

^^of course, I hope y'all understand that even if such a feature did exist on Tesla, at best it'd be an estimate, and probably not very accurate unless it also factored in the temperature changes over night. It's one thing to plug in at say 6:00 pm when its 40 degrees and have the computer calc the time needed to charge to 90%, but then the temperature drops into the teens (or lower) by midnight.....

 

[Silicon Desert]

^^of course, I hope y'all understand that even if such a feature did exist on Tesla, at best it'd be an estimate, and probably not very accurate unless it also factored in the temperature changes over night. It's one thing to plug in at say 6:00 pm when its 40 degrees and have the computer calc the time needed to charge to 90%, but then the temperature drops into the teens (or lower) by midnight.....

Yes, good point and a couple of folks mentioned similar things. I still think it would be a decent approximation since when I have manually charged on my destination charger over the summer nights as compared to really cold 20 degree winter nights of last winter, I saw very little difference in the amount of time it took to charge from various levels during the night. In fact within 15 minutes (less than 1 percent charge) of what I expected.

So sure, even with variables that can occur during the night, it would still be good enough. Now having said that, I can just see the complaints coming in that the estimation was off by 30 seconds and someone will be terribly upset

 

[Big Dog]

Now having said that, I can just see the complaints coming in that the estimation was off by 30 seconds and someone will be terribly upset

Or, more realistically, someone who needed a 100% charge at 5 am sharp for a long trip wakes up to find it only 90%.

But for me, I just plug in and then look at the screen and see how long it will take to charge (4,5, or 6 hours), and then back that time up from when I need it. If I need to go at 5:00 am, and it will take 4 hours, I have the system turn itself on at 1 am. Of course, near the coast in SoCal, a 10 degree temp swing is a lot at night.

 

[BobAbooey]

The cheapest time to charge is when your battery is already naturally warmed up from driving home on your commute.

If you don’t take advantage of that naturally occurring heat, you’ll be throwing it away and paying $$$ to put that heat back.

Folks are way to hung up on maximizing regen at ALL costs.

Now if you need maximum range, or want to pay for a cozy car in the morning, or can’t drive it without regen, then go for for it.

Oh if you have off peak metering it might make sense too. Or some other special deal that it cost $0 at home and $X on the road.

Charge when your battery is already warmed up, so it can get down to putting watts in your battery rather than around it, immediately.

The goal isn’t max wh/mi on the car. It’s minimum total kWh on your electric meter/bill.

So if I’m adding let’s say 40% charge to my car it’s cheaper $ to charge the 40% to a warm battery then a cold one?

 

[mswlogo]

So if I’m adding let’s say 40% charge to my car it’s cheaper $ to charge the 40% to a warm battery then a cold one?

I don’t think it matters how much you really have to charge. Paying to heat your battery will cost money. I suspect (can’t prove), that will always cost more than what regen saves you in money.

So far, for me, it hasn’t been all or nothing. If it’s 40F -ish and showing dots. It will charge at about half the full rate (like 10 mile/hr) for a good hour, using full kw (30A circuit) because it’s heating and charging slowly. And that’s on a partially warmed battery.

 

[rdunniii]

yup, and that is what I do, yet with such a smart car, it would be really easy for Tesla to do the same thing in software so I don't have to wast time with this process.

Like the Chevy Volt has done since 2011.