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Tesla Wall Connector/Charger + Off-Peak

Hey TMC,

Does anyone know if it's ok to put the Gen2 Wall Charger/Connectors on off-peak electrical programs? Essentially the way off-peak works for us is they have a controller box that can flip specific breakers on/off during high utilization in exchange for extremely low kwh costs (like $0.03 if I off peak my car, which seems crazy cheap). Since the breakers can flip at pretty much any time, I'm curious if this is hard on either the Wall Connectors or the vehicle? I usually leave my vehicle plugged in all the time when I'm at home, even if the car is charged to try and reduce battery wear.

Appreciate any thoughts in advance!
 
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DerbyDave

Active Member
Jul 2, 2020
2,253
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Kentucky
On my 2020 Tesla, the power to unlock the charging cable is missing, but you can press the button in the charge port door to manually release the cable if you need to remove it when the power is off (your car may not have this button). You would need to use the interior UI, or perhaps the phone app to unlatch the cable. Also, the car is saying to plug the charge port cable into the car, because it doesn't know it is connected. I believe this means the charge port door will eventually try to close, thinking there is no cable connected. This may damage the door. Turn off your breaker and play with it until you think it is the best method. I think your car has the scheduled charging function which I have used to simulate starting charging after peak hours. Seems to work well if you have this on your model.
 

DerbyDave

Active Member
Jul 2, 2020
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Kentucky
I’m guessing because that has nothing to do with what the OP is asking about.
Scheduled charging is designed primarily to take advantage of off-peak electric rate hours. From the manual:

Scheduled Charging: When you set a scheduled charging time, Model S displays the set time to begin charging when you are parked at the scheduled location. If, at the scheduled time, Model S is not plugged in at the location, charging starts as soon as you plug it in, provided you plug it in within six hours of the scheduled time. If plugged in after six hours, charging does not start until the scheduled time on the next day. To override this setting, touch Start Charging or Stop Charging. When you set a scheduled charging time, Model S displays the set time on the instrument panel and touchscreen.
 

ucmndd

Well-Known Member
Mar 10, 2016
8,341
16,231
California
Scheduled charging is designed primarily to take advantage of off-peak electric rate hours. From the manual:

Scheduled Charging: When you set a scheduled charging time, Model S displays the set time to begin charging when you are parked at the scheduled location. If, at the scheduled time, Model S is not plugged in at the location, charging starts as soon as you plug it in, provided you plug it in within six hours of the scheduled time. If plugged in after six hours, charging does not start until the scheduled time on the next day. To override this setting, touch Start Charging or Stop Charging. When you set a scheduled charging time, Model S displays the set time on the instrument panel and touchscreen.
I’m quite aware of what it does.

It still has nothing to do with what OP is asking.

They are describing a scenario where the UTILITY has control of the circuit breaker the car’s charger is attached to and can turn it on/off at any time as a way of managing demand on the grid.

They’re asking if there is any risk/concern about power being cut to the wall connector at any time, charging or not, potentially multiple times a day. I think the answer to that is generally “no”. But again, scheduled charging has nothing to do with what’s being discussed.
 
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I’m guessing because that has nothing to do with what the OP is asking about.

I’m quite aware of what it does.

It still has nothing to do with what OP is asking.

They are describing a scenario where the UTILITY has control of the circuit breaker the car’s charger is attached to and can turn it on/off at any time as a way of managing demand on the grid.

They’re asking if there is any risk/concern about power being cut to the wall connector at any time, charging or not, potentially multiple times a day. I think the answer to that is generally “no”. But again, scheduled charging has nothing to do with what’s being discussed.
Well maybe the OP doesn't know how scheduled charging works 🤔🤯

And for what is being described it's not the the utility company is flipping breakers as that is extremely unsafe to do on a constant basis as it wears them out and causes them to fail. The utility company installed a box of some sort that will create a switch outside of the panel and open close the circuit that way like they do for A/C in the desert.

In the end IMO I say don't do it, because if you want to use it while it's in off mode it's annoying to have to override it, and sometimes extremely difficult depending on what controller and utility company is used. And the power company shouldn't have any control over anything in the house besides the main coming in from the street.
Stick with scheduled charging or just don't plug it in during peak times.
 

und2000

Member
Supporting Member
May 25, 2021
138
364
Twin Cities, MN
Following up on this discussion, I have a choice with my electric provider where they would install a submeter for off-peak storage (11p - 7a) at a rate of
$0.0440 per kWh (where they don't supply power to the circuit between 7a - 11p), or a time-of-use meter at a rate of
6.74¢ per kWh and insane at on-peak. I'm leaning towards the off-peak storage because I could just have it run overnight, but is it compatible with the Tesla Home Charger to not have power, come on during scheduled charging and work?
 

DerbyDave

Active Member
Jul 2, 2020
2,253
1,306
Kentucky
You will get errors in the app and in your car that there is a problem with the connector if it is connected but not "handshaking" with the car. Also, the wall connector updates when it is not in use (when an update is available). I use the Tesla settings in the car to not start charging until the off-peak time is met. If plugged in, it will delay charging until this time, and will start charging up to 6 hours after this time is met if you plug in after the set start time. To answer your question, though, the charging itself would probably work OK as you describe.

In addition, the car will occasionally use the wall outlet power to operate the electronics in the car when it is not charging, and keep the battery optimized. In your setup, this would not work.
 
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DerbyDave

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Jul 2, 2020
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Kentucky
The car uses shore power only when actually charging or running the HVAC (i.e. preconditioning, etc). That's it.
Turn your AC off and open the door. You will see the wall connector start sending small amounts of power to the car. It also will help keep the big battery temperature from getting too hot or too cold.

Mine turns off and on all the time even without opening the door. I had to check the power levels to make sure it wasn't charging during peak hours. It was just supplying small amounts of power.
 
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und2000

Member
Supporting Member
May 25, 2021
138
364
Twin Cities, MN
You will get errors in the app and in your car that there is a problem with the connector if it is connected but not "handshaking" with the car. Also, the wall connector updates when it is not in use (when an update is available). I use the Tesla settings in the car to not start charging until the off-peak time is met. If plugged in, it will delay charging until this time, and will start charging up to 6 hours after this time is met if you plug in after the set start time. To answer your question, though, the charging itself would probably work OK as you describe.

In addition, the car will occasionally use the wall outlet power to operate the electronics in the car when it is not charging, and keep the battery optimized. In your setup, this would not work.
Thanks! Sounds like it isn't worth the headache to save the additional couple of pennies per kWh. I'll opt for the time-of-use then. Appreciate the insight and feedback.
 

ucmndd

Well-Known Member
Mar 10, 2016
8,341
16,231
California
Turn your AC off and open the door. You will see the wall connector start sending small amounts of power to the car. It also will help keep the big battery temperature from getting too hot or too cold.
I will revise my statement to say that the car uses shore power when a door is open and the car is "on".

Mine turns off and on all the time even without opening the door. I had to check the power levels to make sure it wasn't charging during peak hours. It was just supplying small amounts of power.
There seemed to be a bug in recent firmwares where the car was performing several "micro charges" in relatively rapid succession rather than waiting for a sizable discharge (~3%) in the HV battery before topping off. That's not normal behavior though. There isn't really any way for the car to economically use shore power for "small amounts of power" - the car has to be completely awake, with the HV contactors closed, charging circuitry and DC-DC converters powered, etc etc. There's no practical purpose for the car to do this, certainly none along the lines of "keeping the battery optimized".
 
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DerbyDave

Active Member
Jul 2, 2020
2,253
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Kentucky
I will revise my statement to say that the car uses shore power when a door is open and the car is "on".


There seemed to be a bug in recent firmwares where the car was performing several "micro charges" in relatively rapid succession rather than waiting for a sizable discharge (~3%) in the HV battery before topping off. That's not normal behavior though. There isn't really any way for the car to economically use shore power for "small amounts of power" - the car has to be completely awake, with the HV contactors closed, charging circuitry and DC-DC converters powered, etc etc. There's no practical purpose for the car to do this, certainly none along the lines of "keeping the battery optimized".
By keeping the battery optimized, I do not mean it is being charged, I mean it is being heated or cooled. I hear noises like the fans coming on, and the intakes opening in hot weather. I assume the cooling is on. I agree with certainty there are always actions induced by buggy code.
 
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Since this thread is getting more traction, thought I'd update (which tldr; there really isn't one, right now I'm still paying regular rate).

I'm still torn on how to move forward. There's another program where we are thinking it may be more cost effective to add a separate meter to the house for charging, but still trying to find more details on all the considerations of that.

Given there is a supercharger very close to my home, if I absolutely needed power I could go there and charge, so off-peak seems like a no-brainer. But, I'm still concerned if there are any negative effects to the vehicle if it's plugged in, charging or not, if power "goes out" without notice to the vehicle a few times a month.

Aside, @airborne spoon,
Well maybe the OP doesn't know how scheduled charging works 🤔🤯

And for what is being described it's not the the utility company is flipping breakers as that is extremely unsafe to do on a constant basis as it wears them out and causes them to fail. The utility company installed a box of some sort that will create a switch outside of the panel and open close the circuit that way like they do for A/C in the desert.

In the end IMO I say don't do it, because if you want to use it while it's in off mode it's annoying to have to override it, and sometimes extremely difficult depending on what controller and utility company is used. And the power company shouldn't have any control over anything in the house besides the main coming in from the street.
Stick with scheduled charging or just don't plug it in during peak times.

Please be understanding that the off-peak program you have in California may not be the same for everyone across the USA. Where I live, the power company provides a control box where they can send a signal to it via the power lines to determine which devices should be "off-peaked". There's many "appliances" that people typically put on this program such as water heaters, air conditions, hot tubs, pool pumps, in my case an EV, etc. (things people can likely go without for a few hours at a time). Unlike where you are, there is no "scheduled time" where the power company drops the rate from X to Y time; off-peak comes at times where the power company is experiencing heavy demand and where the "larger grid" may be charging premium rates to power companies to consume electricity. In this case, the power company wouldn't have to "buy" power from the larger grid at premium rates for the "appliances" that are off-peaked in the community to keep costs lower.
 

DerbyDave

Active Member
Jul 2, 2020
2,253
1,306
Kentucky
We have that "demand conservation" program here in KY as well. I was on it years ago before my Tesla. My new AC required frequent communication to the controller and thermostat, and Trane recommended against its use. I also like to control my power, and not let the Utility control my power. I can and do reduce power during high demand, and still meet my requirements better managing this myself. You will still have some usability issues if you put the wall charger under the Utility control to let them turn it off whenever they want. Better you just manage your charge times to not charge during high demand. You can manage this from anywhere your phone may be. Easy, and not complicated. My utility would give me a $5 or $10 credit monthly during the summer while I was on this program.
 

und2000

Member
Supporting Member
May 25, 2021
138
364
Twin Cities, MN
I had electricians out last week. The Tesla installer electrician in our area says 99% use a time of use program vs off peak demand. I’m opting for the time of use program—it’s a little more expensive per kWh, but no risk of having them turn off due to peak demand, as well as the concerns already mentioned on here.
 
From the Tesla wall connector installation guide page 10:

Power Outages
If there is a power outage while Wall Connector is charging a vehicle, charging will automatically resume within 1 to 3 minutes after power restoration. The Wall Connector will display a solid blue light on the faceplate to indicate that it is communicating with the vehicle and waiting to resume charging. Alternatively, pressing the button on the charging handle after power restoration will cause Wall Connector to resume charging immediately.
 

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