Questions about the Wall Connector (speed) and good charging habits

[Nopantz]

Some reasons you might want to use the minus button to charge at a lesser amperage:

• You have a bunch of other stuff running and you want to be nice to your panel or local grid. We do this during the summer when both the upstairs AC and the downstairs AC are running and we are also charging both Tesla’s.
• You want to charge to 100% for a specific trip but since it’s best to not sit with the battery at 100% any longer than necessary you dial down the amps so that the car reaches 100% right before you want to depart and not in the middle of the night.

I turned my home charging way down (24A?) because my electric company charges $1/kwh for the peak 15 mins of the month (irrelevant to the time of day). I had gotten that up to $15 one month! Seems awful for electric car owners, and for me to drop $500 on the hpwc vs using the portable charger.

I mostly charge for free at work so not needing much juice overnight at home.

 

[GSP]

....... my electric company charges $1/kwh for the peak 15 mins of the month (irrelevant to the time of day). I had gotten that up to $15 one month! ...... .

That sounds like a demand charge. Are you sure it isn’t $1/kW?

Although demand charges, based on the highest power demand during the monthly billing period, has traditionally been only applied to large commercial and industrial customers, some utilities are experimenting with charging residential customers for demand.

Since the charge is based on power (rate of energy consumption), the rate is per kW.

Of course, they still charge for the energy used in kWh, on top of the new demand charge.

GSP

 

[Nopantz]

That sounds like a demand charge. Are you sure it isn’t $1/kW?

Although demand charges, based on the highest power demand during the monthly billing period, has traditionally been only applied to large commercial and industrial customers, some utilities are experimenting with charging residential customers for demand.

Since the charge is based on power (rate of energy consumption), the rate is per kW.

Of course, they still charge for the energy used in kWh, on top of the new demand charge.

GSP

I think you are right - max kw during peak 15 mins. Kwh went down to $0.1015.

 

[SageBrush]

I think you are right - max kw during peak 15 mins. Kwh went down to $0.1015.

You utility is encouraging you to charge the car when people are sleeping and your other house loads are minimal. Say, between 11 pm and 5 am.

 

[Nopantz]

You utility is encouraging you to charge the car when people are sleeping and your other house loads are minimal. Say, between 11 pm and 5 am.

You’d think that, but the peak 15 mins is anytime of day. So they are encouraging me to charge slowly more than at night.

 

[SageBrush]

You’d think that, but the peak 15 mins is anytime of day. So they are encouraging me to charge slowly more than at night.

Pre-EV your peak was almost certainly not middle of the night so EV charging during those high load hours would add to your demand charges. The 'smart' move is to charge the EV during the middle of the night at a rate no greater than your daytime peak.

 

[Nopantz]

Would be handy if there was an option to have the M3 choose the charging current for a selected charge time. For example, “charge my car to 80% by 8am (or 10hr from now)”.

 

[tvguy710]

I turned my home charging way down (24A?) because my electric company charges $1/kwh for the peak 15 mins of the month (irrelevant to the time of day). I had gotten that up to $15 one month! Seems awful for electric car owners, and for me to drop $500 on the hpwc vs using the portable charger.

I mostly charge for free at work so not needing much juice overnight at home.

That's interesting from your Utility to do that...

Sidebar question, I plan on doing the same at work, how many miles a day do you drive and how are the charging speeds at work? Also how often do you have to charge at home in the same day you charged at work? Just awaiting my M3, should be ready in about 2 weeks!

 

[dmurphy]

Would be handy if there was an option to have the M3 choose the charging current for a selected charge time. For example, “charge my car to 80% by 8am (or 10hr from now)”.

The Stats app does something sorta-kinda close to that ...

 

[tvguy710]

The Stats app does something sorta-kinda close to that ...

View attachment 428804

What app is this screen grab from?

 

[dmurphy]

The Stats app does something sorta-kinda close to that ...

What app is this screen grab from?

The app is called Stats.

‎Stats: For Tesla Model S/X/3

 

[jebinc]

Is anyone else (besides me) concerned about Stats/Teslafi privacy issues, or vampire drain? While, being an engineer by education, I love data, I’m not sure the potential downside is worth satisfying my data appetite. Eh Tu?

 

[TT97]

Is anyone else (besides me) concerned about Stats/Teslafi privacy issues, or vampire drain? While, being an engineer by education, I love data, I’m not sure the potential downside is worth satisfying my data appetite. Eh Tu?

I have TeslaFi and have no issue with vampire drain.

You just need to have the settings done right. I have been traveling since Wednesday and TeslaFi lets my car sleep 23 hrs 48 min each day. My car wakes up each evening at 9:00 to check if it needs to charge and then goes back to sleep.

Here's my vampire drain while away:

Wed - 1.33 miles/0.3 kWh
Thur - 0.4 miles/0.09 kWh
Fri - 1.79 miles/0.4 kWh (car downloaded/installed 20.4.4 on Friday increasing drain)
Sat - 0.89 miles/0.2 kWh

I'm not concerned about privacy but if you are, you can supply a token to TeslaFi without sharing your Tesla credentials (although at that point I am guessing you will need to give someone else your credentials in order to generate a token).

 

[jebinc]

I have TeslaFi and have no issue with vampire drain.

You just need to have the settings done right. I have been traveling since Wednesday and TeslaFi lets my car sleep 23 hrs 48 min each day. My car wakes up each evening at 9:00 to check if it needs to charge and then goes back to sleep.

Here's my vampire drain while away:

Wed - 1.33 miles/0.3 kWh
Thur - 0.4 miles/0.09 kWh
Fri - 1.79 miles/0.4 kWh (car downloaded/installed 20.4.4 on Friday increasing drain)
Sat - 0.89 miles/0.2 kWh

I'm not concerned about privacy but if you are, you can supply a token to TeslaFi without sharing your Tesla credentials (although at that point I am guessing you will need to give someone else your credentials in order to generate a token).

How does it work with Stats? Both drain and registering/privacy?

 

[Rothgarr]

Is anyone else (besides me) concerned about Stats/Teslafi privacy issues, or vampire drain? While, being an engineer by education, I love data, I’m not sure the potential downside is worth satisfying my data appetite. Eh Tu?

I'm in the same boat as you -- I love data, don't like the idea of giving up my telsa login, even if it's just temporary.

 

[BrokerDon]

Some early Model S could even handle a full 80A (100A wiring/breaker) with their "twin chargers"

Correct. Our 1st generation Tesla High Power Wall Connector ("HPWC") connected to a 100A breaker can charge at 80A / 54 MPH. However the HPWC cable gets pretty warm near the HPWC plug so we set our "nightly" charge to 60A / 42 MPH which still recharges our 2015 P85D with a almost fully depleted battery to 90% with dual 40A chargers in a couple of hours. Plenty fast.

Our son has a 2nd generation Tesla Wall Connector ("WC") on a 60A breaker which charges their 2019 Model 3 LR DM at 48A. Again plenty fast for their "nightly" charge... and much less expensive for materials, labor and electrical permit costs than our 100A HPWC total too.

 

[Nopantz]

That's interesting from your Utility to do that...

Sidebar question, I plan on doing the same at work, how many miles a day do you drive and how are the charging speeds at work? Also how often do you have to charge at home in the same day you charged at work? Just awaiting my M3, should be ready in about 2 weeks!

I get 44mi/hr charge at home at 48A but run it about 12A/11mi. At work they have 30A generic chargers but only get 22mi/hr. Normally I charge 2X/wk at work, maybe 100 miles at a time and almost never at home.

I finally determined how to view my peak electric usage at home. Charging at 48A tends to push me in the 12-15kW peak usage, at night, which makes sense. My normal peak wo charging is 5-7kW, so charging fast at home costs me an extra $5-10 that month, just for that 15 mins. Charging at 1/4 rate should keep me close to my normal peak, especially if done at night.

If I’ve already blown the peak for the month, I guess no reason to not charge fast unless you aren’t sure when the new month starts.

Of course, there are times where you need the fast charge, even during the day. Not sure if the supercharger would be cheaper if convenient.

 

[SageBrush]

I finally determined how to view my peak electric usage at home. Charging at 48A tends to push me in the 12-15kW peak usage, at night, which makes sense. My normal peak wo charging is 5-7kW, so charging fast at home costs me an extra $5-10 that month, just for that 15 mins. Charging at 1/4 rate should keep me close to my normal peak, especially if done at night.

Hold on a minute:
48 amps, 240 volts = 11.5 kW so your low night time load (say, after midnight) is between 0.5 and 3.5 kW
During the day you reach 7 kW.
So if you are careful with your night load being low other than charging you can put ~ 5 - 6 kW into the car and not have any additional demand charges.

If your utility is anything like mine, you can ask for and receive without charge your demand data in 15 minute intervals. It is supplied as a simple spreadsheet. Last year I helped my PV volunteer group analyze load data for customers wondering if they could reduce demand charges with PV + battery. The spreadsheet is done and it only takes me a few minutes to load new data if you are interested in your home.