How to set scheduled charge to maximize saving?

[dhanson865]

My power company charges me super low rates from 12am to 7am. And I have a J1772 charger which will do 32Amp max at my Garage to charge my Model 3 once it comes. I have seen in some video, Tesla can only set the starting charge time, but not end charging time. The maximum charge level could be set though.

Whats the best way to set up , I don’t want the charging go beyond 7am, as it enteres the peak rate.

I am also thinking install a Tesla HPWC which can draw 48amp out of it , so I don’t need worry charging over 7am.

I'd set the car to start charging at 1:01 am (or whatever the smallest time increment past 1am is, I don't know that is minutes, 5 minutes, 15 minutes) with a max charge set at 70% or 80% or whatever you need for a normal days travel.

Why after 1am? Daylight Savings Time.

You won't be charging the full 7 hour window and the utility could bill you wrong around the time change or your time could be off and you could charge at the wrong time.

Ideally you'll charge between 1am and 6am to give yourself a buffer on both ends for time changes or a clock being off by a few minutes.

Unless you drive your car to near 0% all the time 5 hours should be plenty at 32 amps and will definitely be plenty at 48 amps.

 

[Missile Toad]

The following chart lets you pick the peak wind Megawatts delivered on the Texas ERCOT grid. Chances are, the peak (9:00pm here) will also be the lowest $/kW too (your plan may vary).

Winds for 05/16/18|05/17/18 ... Midnight marked with '|'

.16000.............|
.15000.............|
.14000.............|
.13000.............|
.12000.............|
.11000.............|
.10000»............|
..9000..........###i
..8000.........####i#
..7000.........####i###
..6000........#####i######
..5000.......######i####### #
..4000.......######i###########

9783 MW is peak for this interday period... at least according to forecasts.

P.S. Move to Texas, Buy an EV.

 

[dweeks]

In real life it’s not as complicated as some are thinking. If you set scheduled charging to start at midnight, plugged into a 14-50 outlet you’ll get 30 miles per hour of charge. So by 7am you’ll have added 210 miles. How often would you be adding more than that in a night? It will almost always shut off before then, as you’re not usually driving 210 miles in a day. If you are, you need the extra charge for an hour or two after 7 am even if it’s at a higher cost.

This guy gets it. The first example is way too much bother for no additional results. I get 30 miles range per charging hour. I know my 80% target charge is 265 miles (100D). If the car is at 200 miles range, I know I need to charge for a bit more than 2:00. Rinse and repeat for any starting mileage.

 

[jamnmon66]

I definitely agree that it's over-thinking it to bother with anything besides starting the charge at midnight and forgetting it.

But... overthinking is what I do. I've been really into home automation for a few years now & I'm sure you could find a timer to turn off the circuit that you're charging from at a specified time. It will probably cost more than you will ever save in energy costs to find one rated for 240v at 40-60 amps but that's likely the ultimate solution.

 

[David99]

I have the exact same situation. Not sure if it was mentioned here before. I am using an app called Dashboard for Tesla (Android only). It has a very smart charging feature. You tell the app you need to be done charging at lets say 8 am in the morning. You also set a certain time window in which you have the lowest electricity cost. The app will check what the state of charge is on the battery and automatically figure out when it needs to start charging and does so automatically. It will also obey the time window you have given. Once this is set up, you don't have to ever worry about it any more. Every night when you park your car and plug it in, the app will check and do it's work. A positive side effect of using this app and this method is that your car will stay at a lower battery level for a longer time which is good for the longevity of the battery. You could set the timer in your car to start charging as soon as the off peak rate from your power company starts, but in most cases it would start charging earlier than needed and then sit at a higher level for many hours. With the app it will always be done charging on time, charging within the off peak time and it will be easier on the battery.

 

[Rocky_H]

But... overthinking is what I do. I've been really into home automation for a few years now & I'm sure you could find a timer to turn off the circuit that you're charging from at a specified time. It will probably cost more than you will ever save in energy costs to find one rated for 240v at 40-60 amps but that's likely the ultimate solution.

"ultimate" can mean a few things. I would prefer to have the car smoothly end its charging session through its own software controls, rather than relying on suddenly cutting power to the circuit, possibly while the car is in the midst of charging. Maybe it's not going to make a difference, but since that's not how the car normally handles it, that does not sound like a good idea to me to do on purpose or often.

 

[jsmay311]

Disagree in this particular case. Every feature they add is work and adds complexity to the user experience, so it has to be justified.
The problem I see is that if they cut off charging prematurely (let's say you get home at 4am after a late Friday night, and forget that it's set to stop charging at 7am), then you hop in the car at noon on Saturday to try to go somewhere, and you've only charged a bit, you'd be pissed. It would be a bad user experience and likely something someone might bitch to a friend about (even if it was their own fault).

From the company's standpoint, it's better to NOT add the feature, charge the car to the state you asked for, and not care if the customer gets charged an extra buck on their power bill at the end of the month, and not give any additional credence to any range issues.

Anyway, for this particular user, after 7am is probably not peak anyway; it's part peak, and the risk of going over is pretty small. I agree it's a case of overthinking something that will probably never be an issue.

Your concerns are misplaced. If they just copied GM's approach (and, I assume others'), the settings would allow the user to choose to either (a) limit charging strictly to defined off-peak hours, OR (b) aim to do all charging during off-peak hours but also allow for additional charging outside of off-peak hours as necessary to complete the charge. So zero downside.

As for your explicit suggestion that Tesla shouldn't care about their customers' experience or cost of ownership... Are you for real???

 

[jamnmon66]

"ultimate" can mean a few things. I would prefer to have the car smoothly end its charging session through its own software controls, rather than relying on suddenly cutting power to the circuit, possibly while the car is in the midst of charging. Maybe it's not going to make a difference, but since that's not how the car normally handles it, that does not sound like a good idea to me to do on purpose or often.

Ultimate in the sense of *final*. You might be right. I hadn't thought of that. It would definitely solve the power/timing issue but you certainly don't want to harm the car to save a few pennies on energy.

 

[djplong]

I want a scheduled charge that goes like this:

Charge my battery so that it's at 100% at 5AM.

Use case: I'm leaving on a long trip, first thing in the morning, and I want a range charge timed so that I'm almost immediately using it.

 

[David99]

I want a scheduled charge that goes like this:

Charge my battery so that it's at 100% at 5AM.

Use case: I'm leaving on a long trip, first thing in the morning, and I want a range charge timed so that I'm almost immediately using it.

Dashboard for Tesla does that!

 

[davewill]

"ultimate" can mean a few things. I would prefer to have the car smoothly end its charging session through its own software controls, rather than relying on suddenly cutting power to the circuit, possibly while the car is in the midst of charging. Maybe it's not going to make a difference, but since that's not how the car normally handles it, that does not sound like a good idea to me to do on purpose or often.

Actually, if you want to control charging times, it would be easiest to get an EVSE like JuiceBox that has timers built in. Then they can setup whatever charging schedule they like. I have a Blink and a JuicePlug that both have that feature, and I don't think I would ever want an EVSE that didn't.

 

[Reid]

Your concerns are misplaced. If they just copied GM's approach (and, I assume others'), the settings would allow the user to choose to either (a) limit charging strictly to defined off-peak hours, OR (b) aim to do all charging during off-peak hours but also allow for additional charging outside of off-peak hours as necessary to complete the charge. So zero downside.

I'm the kind of person who likes more features and switches, so I'm all for it, I'm just not sure it's in the 'average' customer's interest. You won't get an argument for me if they implement it though!

As for your explicit suggestion that Tesla shouldn't care about their customers' experience or cost of ownership... Are you for real???

My explicit statement was that they should value the customer experience (full charge over 'accidental' undercharging) over an extra dollar in charging costs once in a blue moon.
YMMV.

 

[Rocky_H]

The problem I see is that if they cut off charging prematurely (let's say you get home at 4am after a late Friday night, and forget that it's set to stop charging at 7am), then you hop in the car at noon on Saturday to try to go somewhere, and you've only charged a bit, you'd be pissed. It would be a bad user experience

As for your explicit suggestion that Tesla shouldn't care about their customers' experience or cost of ownership... Are you for real???

I am floored how you got that. @Reid pointed out how implementation of this feature could create a very negative customer experience, and that Tesla should definitely care to not do that.