Schedule Charging and Time of Use Electricity Rate

sjcsale

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#1
I have had Model 3 for 2 months and currently, I charge it when ever I wish.

I am on a fixed rate plan with my electric company and didn't switch to time-of-use rate plan, because wanted to see what kind of usage I put on with Model 3 charging and if time-of-use will make sense.

With 2 months in and that too probably the hottest ones, I pretty certain switching to time-of-use will save me money in the long run.

My utility company provides cheapest rate (super-economy) between 2am-5am which is preceded by next lowest rate (economy). I would like to maximize my charging time during this super-economy time and spill over in economy if needed.

There seems to be no way in Tesla to tell the car, that it should stop charging at say 5am and calculate backward to find when it should start charging. Since, it already estimates the time it will take to charge up to the configured limit, calculating backward to find start time should be possible.

Am i thinking this right? Is it already possible to do so? Example rate schedule attached.
Suggestions. Opinions please.
 

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Little1er

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#2
Not sure if you can set it to work backwards like that. I would probably just set the start time at 11PM when your economy rates start.

Super envious of your energy rates. My peak here in CA is $0.47 and lowest rate is $0.12.
 

garsh

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#3
There seems to be no way in Tesla to tell the car, that it should stop charging at say 5am and calculate backward to find when it should start charging.
I believe that is correct.

But since "economy" time continues for two hours after "super economy" ends, I suggest that you set it to begin charging at 3am, and hope that it finishes by 7am. What charging rate do you have at home?

 

sjcsale

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#4
I believe that is correct.

But since "economy" time continues for two hours after "super economy" ends, I suggest that you set it to begin charging at 3am, and hope that it finishes by 7am. What charging rate do you have at home?
I have a HPWC installed and hence can squeeze high rate of charging at 48A during that time slot.
But you are right, if I start at 2am or 3am based on season, I can get the maximum range added during the super-economy rate.

Would be cool, if the car could do this though. :cool:
 

Birdman

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#5
If the car is set to start charging at a certain time (for example - start charging at 2 am and charge until 80%), I assume that one would just plug in the car before you go to bed (or when you get home) and assuming the scheduled charging has been set up, there is no need to do anything further. At 2 am, it will start charging and then take as long as it needs to get to 80%, and then shut off - correct?.
 

sjcsale

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#6
If the car is set to start charging at a certain time (for example - start charging at 2 am and charge until 80%), I assume that one would just plug in the car before you go to bed (or when you get home) and assuming the scheduled charging has been set up, there is no need to do anything further. At 2 am, it will start charging and then take as long as it needs to get to 80%, and then shut off - correct?.

You are right @Birdman that is the current behavior of the charging software.
 

garsh

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#7
If the car is set to start charging at a certain time (for example - start charging at 2 am and charge until 80%), I assume that one would just plug in the car before you go to bed (or when you get home) and assuming the scheduled charging has been set up, there is no need to do anything further. At 2 am, it will start charging and then take as long as it needs to get to 80%, and then shut off - correct?.
Note that if you plug the car in within 6 hours of the scheduled start time it will immediately start charging.

So if you have the start time set for 3am, and you plug the car in at 8:59am, it will immediately start charging until it reaches the charging limit. Keep that in mind. If you plug it in after 9am, then it will wait until 3am the next morning to start charging.

https://www.tesla.com/sites/default/files/blog_attachments/software_update_4.3.pdf
 

sjcsale

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#8
Note that if you plug the car in within 6 hours of the scheduled start time it will immediately start charging.

So if you have the start time set for 3am, and you plug the car in at 8:59am, it will immediately start charging until it reaches the charging limit. Keep that in mind. If you plug it in after 9am, then it will wait until 3am the next morning to start charging.

https://www.tesla.com/sites/default/files/blog_attachments/software_update_4.3.pdf
Thanks for pointing this out @garsh -- I did not know this kind of logic existed.
 

Ed Woodrick

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#10
If you are driving 12,000 miles per year, 1,000 per month, and you are using 250 wh/mile, then you need 250 kWhr to charge per month.
At the cheapest rate, that's $10/month. At the highest, it's $25.

You could just stay in the same rate and laugh when your average monthly bill is only about $15 and then remember what your gas bill was.
You know "Like It could even fill up once for $15" hahaha
 

Jason F

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#11
Note to those looking at the rates and drooling. Without seeing the delivery charge and fixed fees they charge per month it may be significantly higher. I know some places have a rather large monthly fee. Where I am in NJ there is no time TOU rates option but we can pick our provider. I also have solar. My rate is <10 cents /kWH total with delivery charge. The monthly fee is about $1.50. We use a lot of energy for AC during the summer so not sure how TOU would work out for me.
 

PNWmisty

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#12
Note to those looking at the rates and drooling. Without seeing the delivery charge and fixed fees they charge per month it may be significantly higher. I know some places have a rather large monthly fee.
How are large fixed monthly fees even relevant here? Assuming you use electricity for purposes other than charging your EV, you have to pay those fixed monthly fees anyway. It shouldn't affect your strategy (at all) of charging during the lowest rate periods to reduce your cost per kWh.

Even if you roll in the fixed monthly fees to determine the true cost per kWh, the increased consumption of an EV will amortize those fixed fees over a larger number of kWh and reduce the cost per kWh paid for household consumption. In other words, the EV charging cost really is the per kWh charge, regardless of fixed monthly charges. And it's really cheap!
 

Frank99

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#13
It can become a game to maximize the power you use during the super-cheap periods. I currently use 90% of my daily electrical usage during off-peak hours - and it'd be almost 100% except my wife is home during the day which means the A/C has to run during on-peak hours. But with timers on the pool, spa, hot water heater, and family trained not to run laundry during on-peak hour, it's not too hard to make TOU pricing pay off.
 

John

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#14
Consider this, if those rates are correct, you are only talking 0.0046 cents per KWh difference.That is about 3 cents an hour at a 7 KW charge rate.
This. Set it for 11pm, and spring for the pennies.
 

Reid

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#15
Just charge every day at 48a, scheduled charging, and through trial and error you can set the charge limit if necessary to avoid charging at a higher cost.

That said, 4c/kWh vs 3c is basically nothing. I think our off-peak is like 16c :D
 
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#16
I agree there should be a feature allowing for a configurable cutoff time. Our TOU rates here in central IL are excellent. Lately, I can grab a kwh for 1.7-2.0¢ between 3am and 5am. I looked at the pricing history over the last few years and have even found hours for which the rate was 0.0¢! powersmartpricing dot org has our rates.
 

Fishn4life

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#17
Anyone here have trouble with their M3 charging with a delayed timer? We will do a 2 or 4 hour delay with our wall charger (40 amp) and works fine with our Chevy EV but is not working with the M3. The delay charging was working before this last update. Just thought I’d throw it out here since we are talking TOU.

BTW, in So Cal, off peak is $.13 / kWh and on peak is $.48 / kWh. Makes for a nice “sell high, buy low” with solar :)
 

PNWmisty

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#18
Anyone here have trouble with their M3 charging with a delayed timer? We will do a 2 or 4 hour delay with our wall charger (40 amp) and works fine with our Chevy EV but is not working with the M3. The delay charging was working before this last update. Just thought I’d throw it out here since we are talking TOU.
I've only tried the delayed charging once (Ver. 2018.32.1) and it failed to start charging at the proper time. I assumed it was because after I set the start time I used the app to stop the programmed charging and then I tried to re-initiate the same delayed program. So I thought it was my fault but more investigation is needed.
 

PNWmisty

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#19
I agree there should be a feature allowing for a configurable cutoff time. Our TOU rates here in central IL are excellent. Lately, I can grab a kwh for 1.7-2.0¢ between 3am and 5am. I looked at the pricing history over the last few years and have even found hours for which the rate was 0.0¢! powersmartpricing dot org has our rates.
Wow! It looks like you have access to some really low rates. And that is the best reason to have the capability to charge as fast as possible during the low rates. If everyone did this it would help balance the load on the grid (since the cheapest rates happen when there is a surplus of electricity).

Of course, electricity for your Model 3 is so cheap compared to a comparable ICE car it's not a big deal but It's in my nature to try to maximize everything (savings in this case) even though the actual dollars we are talking about are almost insignificant.
 

glavewu

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#20
Is this scheduled charging GPS enhanced? If I set schedule charge at 12am, what gonna happen if I plug into a public charge point during day?