Work From Home Charging

[m3fan2023]

Hey guys, I'm planning to buy a Tesla M3. I work from home and don't drive much, just errands here and there. I plan to charge using 110v since I work from home and leave the car plugged in all day until I have to go somewhere.

Would my power bill increase a lot leaving the car plugged in all day? I've read that Tesla recommends keeping the car plugged in even after the car is fully charged. I'm also wondering if I could unplug the car when it's fully charged to save some money. If I leave the car plugged in, it might end up costing more than if I kept my gas vehicle. Thanks.

 

[m3fan2023]

Sorry if I posted in the wrong section. I'm new here and can't figure out how to move my post.

 

[LoudMusic]

In my experience so long as the car is 'asleep' the power consumption is inconsequential. My electricity is rather inexpensive, though, at about $0.14/kwh.

The car puts itself to sleep after a period of inactivity so long as the Sentry Mode is disabled, cabin overheat is disabled, and you aren't constantly checking in on it from the mobile app There may be more circumstances that I am unaware of, but those are the big ones.

 

[m3fan2023]

In my experience so long as the car is 'asleep' the power consumption is inconsequential. My electricity is rather inexpensive, though, at about $0.14/kwh.

The car puts itself to sleep after a period of inactivity so long as the Sentry Mode is disabled, cabin overheat is disabled, and you aren't constantly checking in on it from the mobile app There may be more circumstances that I am unaware of, but those are the big ones.

Thank you @LoudMusic! I can't wait to get one!

 

[charlieaf92]

Hey welcome. Great choice of cars, you won't regret it. We moved last year and for about 5 months I used 110v charging until I got around to installing my wall connector. I, too, work from home and found it to be more than adequate.

You can change what level you want your car to charge to from the app, or car itself. Tesla recommend < 90% to limit the stress on the battery. I usually just set mine to 70% which is always more than enough. Tesla also recommends ABC - always be charging. Leaving your car plugged in allows the battery management system to work the way it was intended. It will use the power it needs, but not "waste" any. To put things in perspective, a full charge about 0.14/kw should cost in the ballpark of $9 or so. However you will hardly ever be doing a full charge in one go. Most days (if you drive it) you'll find you use 5-10% or your pack capacity so you'll spend about $0.50 or so on charging. There is no scenario with home charging where it will ever cost more than a gas vehicle at current electricity and gasoline prices.

 

[jjrandorin]

Sorry if I posted in the wrong section. I'm new here and can't figure out how to move my post.

(moderator note)

Welcome to TMC.

It requires moderator action to move threads here at TMC. I moved this thread for you to the correct subforum.

 

[m3fan2023]

(moderator note)

Welcome to TMC.

It requires moderator action to move threads here at TMC. I moved this thread for you to the correct subforum.

Thank you! And sorry, I realized I posted in the main forum right after I posted.

 

[m3fan2023]

Hey welcome. Great choice of cars, you won't regret it. We moved last year and for about 5 months I used 110v charging until I got around to installing my wall connector. I, too, work from home and found it to be more than adequate.

You can change what level you want your car to charge to from the app, or car itself. Tesla recommend < 90% to limit the stress on the battery. I usually just set mine to 70% which is always more than enough. Tesla also recommends ABC - always be charging. Leaving your car plugged in allows the battery management system to work the way it was intended. It will use the power it needs, but not "waste" any. To put things in perspective, a full charge about 0.14/kw should cost in the ballpark of $9 or so. However you will hardly ever be doing a full charge in one go. Most days (if you drive it) you'll find you use 5-10% or your pack capacity so you'll spend about $0.50 or so on charging. There is no scenario with home charging where it will ever cost more than a gas vehicle at current electricity and gasoline prices.

Thank you @charlieaf92! I've been finding bits of information to answer my question online but haven't been able to find the level of detail as stated in your post.

 

[brianbcc]

I have a new (2mo) 2023 M3 that i exclusivity charge via the mobile connector on 120v. No issues as i drive maybe 20 miles per day, if that.
The car automatically stops charging when it's full, so i just leave it plugged in daily. Some days don't even use the car.
Our electricity here in Santa Clara is $0.12 so it's quite cheap anyway.
With the M3 SR, I've estimated that it charges about 2% per hour on 120v, so from about 20%, fully charged overnight.
(For me, 20% is about 45-50 miles for reference)
Good enough for me since it's really only for errands as I also WFH.
Hope that helps!

 

[m3fan2023]

I have a new (2mo) 2023 M3 that i exclusivity charge via the mobile connector on 120v. No issues as i drive maybe 20 miles per day, if that.
The car automatically stops charging when it's full, so i just leave it plugged in daily. Some days don't even use the car.
Our electricity here in Santa Clara is $0.12 so it's quite cheap anyway.
With the M3 SR, I've estimated that it charges about 2% per hour on 120v, so from about 20%, fully charged overnight.
(For me, 20% is about 45-50 miles for reference)
Good enough for me since it's really only for errands as I also WFH.
Hope that helps!

Thank you @brianbcc! This was very helpful. It was nice to read and see how my situation will be very similar to yours.

 

[brianbcc]

Thank you @brianbcc! This was very helpful. It was nice to read and see how my situation will be very similar to yours.

Just to clarify, i meant [down] 20% daily, not battery level at 20%.
And quick reminder, if you're looking at M3, the new LFP battery is recommended to always be plugged anyway.
Cheers!

 

[Park2670]

All other posts are correct here. The car will only pull power for charging the battery, or if you precondition the interior.

Might as well leave it plugged in for either events to happen. Otherwise, its pulling nothing... I have verified with an energy monitor that my Wall Connector only pulls 2 watts when its not charging the car.

 

[K.I.T.T.23]

Welcome to the Tesla family @m3fan2023 ! I would recommend having 220v charging available at home (not sure if you said you planned on having it installed or not) but there is no harm nor additional cost with charging at 110v.

I am not sure (please correct me anyone who knows better) but from what I understand at the lower voltage it is actually slightly more efficient while significantly slower. It is also better for the battery!

I had a M3SR+ for a couple years and loved it. It is a great car, plenty of features, and quite comfortable. I discovered that 110v charging was just fine 90% of the time, but there were instances where I really needed to charge at the faster rate as I had more driving to do later in the day.

Of course, now I drive 140 miles a day for work... so the 2019 M3SR+ was just a bit too short of range for me.

 

[Park2670]

Welcome to the Tesla family @m3fan2023 ! I would recommend having 220v charging available at home (not sure if you said you planned on having it installed or not) but there is no harm nor additional cost with charging at 110v.

I am not sure (please correct me anyone who knows better) but from what I understand at the lower voltage it is actually slightly more efficient while significantly slower. It is also better for the battery!

I had a M3SR+ for a couple years and loved it. It is a great car, plenty of features, and quite comfortable. I discovered that 110v charging was just fine 90% of the time, but there were instances where I really needed to charge at the faster rate as I had more driving to do later in the day.

Of course, now I drive 140 miles a day for work... so the 2019 M3SR+ was just a bit too short of range for me.

240v charging is actually more efficient by a tiny amount. Because it doesnt need to run all of the ancillary items for as long.

I bet it would be the difference of a few dollars per month. Not a huge deal in my opinion.

 

[Spalding]

For charging at home, the key is to set up time of use (TOU) plan with your electric utility - lowering your charging rates at various times of the day. I would think that all utilities offer some variation on this. Obviously, you have to find a plan that gives a beneficial rate for the time of day you plan on charging. Inevitably, most plans will discourage (i.e., charge higher rates) during peak usage times - usually late afternoon, when it's hottest and people are running their a/c. Some plan surely offers a meaningful reducation in the early morning hours.

My TOU plan (with So. Cal. Edison) offers rates that are about one quarter peak rates, but that's for overnight charging (after 9:00 pm to 8:00 am). 8:00 am to 4:00 pm is only a slight increase. But between 4:00 pm and 9:00 pm, the price skyrockets. So long as you don't make it a habit to run heavy appliances between 4 and 9, you'll save a ton.

 

[Darmie]

If I understand your concern, it's that the car will take more energy if it's kept plugged in and that's not the case. Think more on what will cause battery drain. You didn't mention if the car will be garage kept. This will make a big difference in power use. The car will use more energy to keep the battery and inside of the vehicle cool. Depending on your location, it may have to keep things warm. Keeping sentry on will consume more power as well. The vehicle will go into a sleep mode for most of the time it's not being used which conserves power. Checking the car with the app, sentry mode or if the vehicle has to cool or heat the battery or inside will keep the car from sleeping. Tesla has always recommended keeping the car plugged in, although it's never recommended to keep it fully charged. Objectively hovering the battery pack around 50% will yield better longevity. Of course, this topic creates it's own debates with miles and miles of threads. It's already been recommended to check with your utility company and see if there are off peak plans and such and attempt to save money in that direction. Tesla now has scheduled charging so you can take advantage of lower rates charging during those times. I think you should look into a tesla wall connector anyway and when or if you have one installed, future proof your residence by pre wiring for a second charger. Yes, it happens, there are many including myself that own two and a 3rd tesla is in our future. Also, one other thing. Check with your utility company and tax advisor for there can be rebates and tax incentives for installing a charger.

Best of luck with your purchase. Have fun and hang out here on TMC for many more answers.

 

[SageBrush]

240v charging is actually more efficient by a tiny amount.

5 - 10%

 

[Wrenching Fool]

In my experience, 240V charging is actually quite a bit more efficient. My calculations have shown about 87% charging efficiency on 120V vs 95-96% charging efficiency on 240V/48A. Now, that efficiency is power from the vehicle charge inlet vs what actually goes into the battery, so there may some efficiency difference on the source/EVSE side, but I suspect it is insignificant compared to the vehicle side. The difference in battery wear between charging with 120V at 1.2kw vs 240V at 7-11kw is so tiny that it may as well be nonexistent. Even max L2 charging speeds of 48A/11kw is essentially trickle charging for a modern EV and will not generate any noticeable amount of heat in the battery.

 

[jay1122]

Hmm, I always feels EV is better if you drive big miles due to the cheaper fuel and maintenance cost. If I am driving so little, I probably will take this opportunity and buy a special car with poor MPG that has good resale values. Like C8 corvette or Bronco. EV is very good for daily driving though.

 

[TornadoTJ]

For now we mostly charge on 110v since on a typical day the car will at the longest see 30 miles a day, but usually much less. We saw almost no bump on our bill, but here we pay $0.10 per kWh.

I also work from home, my wife drives to work twice a week, 15 miles each way.