You probably don't need fast charge speed at home

[ivan801]

So model 3 is my second EV and because of the location of my 240V outlet I have to back it into my garage to charge it. And that is a real pain to do. So I started out just charging it with 120V 15 amp outlet. Because of my commute (60 miles per day), that was doable but a bit too slow for me.

After ordering a plug from Tesla that supports 120V 20 amp outlet I've been just fine. I would say that for majority of Tesla owners 120V 15 amp would work, as long as you are willing to plug it in every night. I've only used my 240V charger one time so far (and concluded that backing the car into the garage is no fun at all).

I guess what I am saying is that before you all rush out and spend a small fortune on pulling electrical for your new Tesla, consider all the charging options:

120V 15 amp -- regular outlet that you already have in the garage
120V 20 amp -- you probably already have it in the garage, just see if the there is a horizontal opening next to left vertical opening in your outlet
240V 15 amp -- aka NEMA 6-15. This is especially useful if you already have a dedicated 120V 20 amp outlet in the garage, as you should be able to change out the breaker and the outlet without having to pull a new wire

Options go up from here, but with how economical Model 3 is, I would bet that just about anyone on this forum would be just fine with using NEMA 6-15.

Now, if you HAVE to pull a new wire, and your panel can easily support it, then yes, go with NEMA 14-50 or a wall charger. But before you spend money on it, think if you really NEED that kind of charge rate. I would argue that those who drive less than 1k miles per month can do just fine with a regular outlet.

 

[CarterStC]

Summon?

 

[ivan801]

Summon?

Too scared to try

 

[combo]

I agree, many people don't need high amperage charging.

Due to a lack of juice coming into the house (100A service that's essentially already maxed out), I chose to add a 20A 240V circuit so I can charge at 16A while not overloading my panel. It is serving my needs well (1k miles per month, 20-30 miles per weekday). I usually tell it to start around 2 a.m. and it is nearly finished by the time I leave for work. On the plus side, the battery is warm in the winter.

 

[Eno Deb]

While I agree that not everyone needs a 14-50, I would not want to downgrade to anything less than my current 30A dryer outlet. On weekdays I have 8 hours of cheap electricity per day in my TOU plan. In that time I can add about 175 miles of range from the 30A outlet, which allows me to quickly get back to my usual 70% charge after long trips. On a 120V outlet that would take me several days.

 

[ivan801]

While I agree that not everyone needs a 14-50, I would not want to downgrade to anything less than my current 30A dryer outlet. On weekdays I have 8 hours of cheap electricity per day in my TOU plan. In that time I can add about 175 miles of range from the 30A outlet, which allows me to quickly get back to my usual 70% charge after long trips. On a 120V outlet that would take me several days.

Agreed, if you have access to TOU plan, you may need to have a bigger circuit. Even so, 20 or 30 AMP outlet should be plenty. My point is start small, move up if you have to.

 

[Emmexx1]

I would tend to agree with this. A typical daily commute of 10 miles in warmish climate? Yup, that 120v 20A outlet would be good. Any commute over 20 miles in a climate with single digit cold temps, or even teens, I definitely suggest that 240 outlet.

 

[mswlogo]

Since you have a larger amp circuit as backup you probably feel more confident using 120V daily. Without that you might feel different. How hard could it possibly be to move an outlet 20 feet. I’d do it for free if you were my neighbor (and I have).

Not sure if 120V is as efficient as 240V. Based on the charge rates

that 20A 120V is 4 mph
that 20A 240V is 15 mph !

That’s 3.75x faster charging for only twice the circuit capacity. SAME size wire too !!

If money is tight, yeah install 20A 240V

Also in seriously cold conditions most folks believe a 120V circuit will NOT cut it. It will have no reserve for heating battery. And charge at 1 mph for days. Also no reserve for heating cabin, which is 2000 watts alone (that alone exceeds the 20A 120V circuit ALONE). Folks are guessing battery heating is 4000 watts.

Have to disagree with OP.

Why buy $60k - $80k car and cheap out on proper charging setup. <Shaking head> Even a modest 20A to 30A will typically cost peanuts.

Install the largest you can to the point it starts to get expensive. Like let’s say it’s $400 for 30A 240V. But Your panel can’t take say 40A and needs service beefed up and might cost $2000. Then get the 30A. It would be really rare you can’t install a 20A 240V which is so much better than 120V.

 

[eprosenx]

So while I have always been an advocate of having the max charge capability available (where cost feasible) as it means you are least likely to ever be limited by your car, new data in the last few weeks here in the colder weather makes me an even stronger advocate.

Not only does consumption go up drastically in the winter (and hence charging needs), but the data about how much power the car can pull from the wall to heat the battery and cabin up prior to driving makes me think that having 48 amps of 240v available from a Wall Connector is even more valuable.

See these two threads for graphs I have posted showing how my car draws 10.5kW even in temperatures that are not all that cold.

Warming the car and battery from shore power - 60a Wall Connector helpful

Shore power usage during morning warmup

I totally agree that spending 60k on a car and then cheaping out on $1000 for a solid charging solution at home seems silly. The wiring for a solid home charging solution is likely to be in use for decades, so you can amortize the cost over that time.

 

[Need]

Agreed, if you have access to TOU plan, you may need to have a bigger circuit. Even so, 20 or 30 AMP outlet should be plenty. My point is start small, move up if you have to.

With TOU plan, you also have to consider the time you left for work. I leave for work just before 4am. So from 10pm to 4am, I have just under 6 hours of charging time. I drove 125 miles a day, so the 6 hours on NEMA 14-50 (32 amp) is enough to get me to back to 90% (really only need to charge about 4 hours). But if I had a dryer outlet, I would be cutting it pretty close to recover the daily usage. Theoretically, I could have charged every 2 days with the Model 3, but I can't recover 250 miles in 6 hours.

But I agree that most people don't drive 125 miles daily and don't have to wake up at 3am to get ready for work, so 20amp could work.

 

[jkoya]

With TOU plan, you also have to consider the time you left for work. I leave for work just before 4am.

I agree with you completely. We have 2 solar arrays and SMUD (Sacramento Municipal Utility District) has a special TOU plan for electric charging for solar customers. Their special TOU times were from midnight to 6 AM. I used to leave for work at 2:30 AM and this would never work because our cars only had 3.3 kwh onboard chargers.

 

[SigNC]

if you can "upgrade" from 15amp 120 to plugging into a 20amp 120 with the correct plug it will make a very large difference in charging speed. It's at least 50% faster because a lower % is lost to charging overhead.

 

[Eno Deb]

if you can "upgrade" from 15amp 120 to plugging into a 20amp 120 with the correct plug it will make a very large difference in charging speed. It's at least 50% faster because a lower % is lost to charging overhead.

Yeah, but it's still only ~7 miles/hour. I'd still recommend to go to 240V. If rewiring is a problem you can keep the existing ampacity (i.e. only replace breakers and change the outlet to a NEMA 6-15 or 6-20).

 

[ivan801]

Since you have a larger amp circuit as backup you probably feel more confident using 120V daily. Without that you might feel different. How hard could it possibly be to move an outlet 20 feet. I’d do it for free if you were my neighbor (and I have).

Not sure if 120V is as efficient as 240V. Based on the charge rates

that 20A 120V is 4 mph
that 20A 240V is 15 mph !

That’s 3.75x faster charging for only twice the circuit capacity. SAME size wire too !!

If money is tight, yeah install 20A 240V

Also in seriously cold conditions most folks believe a 120V circuit will NOT cut it. It will have no reserve for heating battery. And charge at 1 mph for days. Also no reserve for heating cabin, which is 2000 watts alone (that alone exceeds the 20A 120V circuit ALONE). Folks are guessing battery heating is 4000 watts.

Have to disagree with OP.

I know you feel like you are disagreeing with me, but I believe we are more or less on the same page. A couple of comments: moving 240V plug for me is not a good option because then I will not reach my LEAF. I know I can get J1772 extension cord, so that would be my lowest cost option.

Also, for Model 3, my 20 A 120V outlet gives me around 7 mph. I know that number will go down some in the middle of the winter, but model 3 is very economical.

In my unique case, both of my panels are totally maxed out, including doubling up anything that can be doubled up. For some reason, even though my house was only built about 15 years ago, builder only provisioned 200 A service (my house is almost 5000 SF). I probably could find a way to increase my 20 A 120 V circuit to 20 A 240 V circuit, but even that would require re-shuffling half of my panel.

I could also use something like RV buddy to leverage my NEMA 14-50 circuit into two lines.

And I do have to admit that I have a heated 3-car garage, so all my cars spend winters in balmy 50+ F temperatures.

Bottom line: I am not unwilling to spend the money to upgrade. My original point was that perhaps we don't all need as much power as we think we need, and charging constraints should not prevent most of us from buying an EV.

 

[mswlogo]

I know you feel like you are disagreeing with me, but I believe we are more or less on the same page. A couple of comments: moving 240V plug for me is not a good option because then I will not reach my LEAF. I know I can get J1772 extension cord, so that would be my lowest cost option.

Also, for Model 3, my 20 A 120V outlet gives me around 7 mph. I know that number will go down some in the middle of the winter, but model 3 is very economical.

In my unique case, both of my panels are totally maxed out, including doubling up anything that can be doubled up. For some reason, even though my house was only built about 15 years ago, builder only provisioned 200 A service (my house is almost 5000 SF). I probably could find a way to increase my 20 A 120 V circuit to 20 A 240 V circuit, but even that would require re-shuffling half of my panel.

I could also use something like RV buddy to leverage my NEMA 14-50 circuit into two lines.

And I do have to admit that I have a heated 3-car garage, so all my cars spend winters in balmy 50+ F temperatures.

Bottom line: I am not unwilling to spend the money to upgrade. My original point was that perhaps we don't all need as much power as we think we need, and charging constraints should not prevent most of us from buying an EV.

Fair enough. But I'm sure, like I said, it gives you some relief that you can charge faster at home if you needed to and not everyone has a heated garage. My garage is not heated and often at 50F-ish when it's 30F-ish out.

I'm am surprised you are getting 7 mph though. I wonder if it's an error on Tesla page because I'm surprised it doesn't jive with 20A 240 (i.e. it says 4 mph). I think I tested 120V once and it was dreadfully slow. But for anyone that does need to deal with cold environment I think 120V is going to be very inconvenient, if not impossible in some situations. Folks are not quite sure yet that, at low amp 120V, it may not need to heat the battery because it can charge the battery cold at that low rate (to a point). But it certainly would not work well on a Model S in cold weather. I suspect if you have a "Snow Flake" on your battery your gonna wait a long time.

I also find it hard to believe it would be that hard to "twin up" a couple breakers on a 200A Panel to achieve a modest 240 Circuit. I added a 40A to 150 Amp panel and added 30A off an existing 30A with a switch on a 100A panel.

I don't know the legal issues around just having two 240 Outlets off your one 240 Circuit. No different than 4 outlets on a 120V 20A Circuit that could get over loaded. But there might be other rules for higher amp circuits.

I put a A/B Switch for like $30 between a 30A Heater and a 14-30 outlet. I rarely ever use the heater.

It's also hard to know ahead what you might need. Like lets say I need to travel one day for work on a Friday but planned on a weekend when I got home (which I personally do a lot). Be nice to add a 100 miles to the car before I go.

If you own a 5000 sq ft home, with a maxed out 200A panel (meaning you must have a lot of other "stuff"), a Tesla. I'm hard pressed to see why you would not "clean it up" a bit. It would cost peanuts by the sound of it. The car itself will dwarf any other appliance you have unless you have electric heat.

This is a "modest" 30A 240V Circuit (22 mph) adding 60 miles (I think). Green is the solar which wasn't a great solar day.

Sure normal, day to day 120V would be fine. It's those outliers you will run into (forget to plug in, back to back trip, extreme cold spell) that 120V could leave you stranded. Why risk it after such a large investment.

 

[mswlogo]

So while I have always been an advocate of having the max charge capability available (where cost feasible) as it means you are least likely to ever be limited by your car, new data in the last few weeks here in the colder weather makes me an even stronger advocate.

Not only does consumption go up drastically in the winter (and hence charging needs), but the data about how much power the car can pull from the wall to heat the battery and cabin up prior to driving makes me think that having 48 amps of 240v available from a Wall Connector is even more valuable.

See these two threads for graphs I have posted showing how my car draws 10.5kW even in temperatures that are not all that cold.

Warming the car and battery from shore power - 60a Wall Connector helpful

Shore power usage during morning warmup

I totally agree that spending 60k on a car and then cheaping out on $1000 for a solid charging solution at home seems silly. The wiring for a solid home charging solution is likely to be in use for decades, so you can amortize the cost over that time.

I tend to agree. I'm a little leery my 30A 240V could even end up being shy. But I also do have an attached (insulated as of today ) garage, so I believe I'll be very comfortable. If I find myself EVER close to struggling I will up it further. I don't know how cold my garage will get now that's insulated when it reaches single digits. I would never waste energy heating my garage. It gets some heat from what leaks off the house and that's it.

But no matter how "warm" the garage is, I might just have got home (short commute) on a day that's single digits out and I want to charge when I get home and want to take a long trip that evening !!

 

[mswlogo]

Yeah, but it's still only ~7 miles/hour. I'd still recommend to go to 240V. If rewiring is a problem you can keep the existing ampacity (i.e. only replace breakers and change the outlet to a NEMA 6-15 or 6-20).

I agree, but keep in mind many folks plugging into a 120V circuit are typically not plugging into a dedicated circuit and switching everything on that circuit to 240V is not always practical. For example, a garage outlet might be shared with the "wash room" or a "work shop". If it's outdoor outlet their might be several on that circuit and you might not want to lose 120V on those other outlets. Rarely is there 1 Outlet on a 20A 120V Circuit. But they do happen occasionally. But yeah, a 6-20 is ridiculously easy and cheap to do.

Folks with rentals, or condos, or no parking near the house may have no choice. But if you own your own home with a heated 3 car garage and 200A panel recommending 120V seems silly.

 

[Eno Deb]

I'm am surprised you are getting 7 mph though. I wonder if it's an error on Tesla page because I'm surprised it doesn't jive with 20A 240 (i.e. it says 4 mph). I think I tested 120V once and it was dreadfully slow.

FWIW: since the NEMA 10-30 adapter was sold out when I got my car I initially charged from 120V, first with the included 5-15 and later with the 5-20 adapter. With 5-15 I got around 5 miles/hour and with the 5-20 around 7 according to the app. Both values are a bit higher than Tesla's estimate.

 

[gilscales]

In my unique case, both of my panels are totally maxed out, including doubling up anything that can be doubled up. For some reason, even though my house was only built about 15 years ago, builder only provisioned 200 A service (my house is almost 5000 SF). I probably could find a way to increase my 20 A 120 V circuit to 20 A 240 V circuit, but even that would require re-shuffling half of my panel.

Well this might seems like an odd (overkill) solution to a problem that you seem not to have but in the event you did find you would like a 20A 240V charging set up then you could hook up a hard wired HPWC with that 120V 20A circuit if it is a dedicated home run line (it should be) as you do not need a neutral wire for the HPWC you could use the neutral wire as power (assuming you could figure out the breaker situation on the panel end, probably could be done with a quad style breaker)

 

[mswlogo]

Well this might seems like an odd (overkill) solution to a problem that you seem not to have but in the event you did find you would like a 20A 240V charging set up then you could hook up a hard wired HPWC with that 120V 20A circuit if it is a dedicated home run line (it should be) as you do not need a neutral wire for the HPWC you could use the neutral wire as power (assuming you could figure out the breaker situation on the panel end, probably could be done with a quad style breaker)

There is nothing magical about the HPWC. He could install a 6-20 outlet (if it's dedicated) just as easily.

The HPWC really pays off when you go above 40A or you need to plug in outdoors. It would be a bit overkill for 20A 240V indoors IMHO. But if you were thinking of upgrading later or moving then it might make sense.