"Getting by" on a 15A outlet?

[LoudMusic]

There's a pretty constant flow of people asking about putting high amperage charging options on their property or apartment complex. I fully support that! Before the Tesla Wall Connector got so cheap I put a NEMA 14-50 outlet in my garage and charge at 240v32a with my mobile connector. Full charge in just under 10 hours is great!

But is it even necessary? Can we survive on a 15A outlet?

I ran some numbers and I'm pretty sure my daily driving would be plenty comfortable using only a 15A outlet in my garage and the mobile connector. I have a 2020 Model Y Long Range Dual Motor. I believe that's a 75kwh battery?

Monday: Start with 90% charge at 67500wh
60 mile round trip to work and back, estimate 350wh/mile because I drive like a lunatic in the hills outside of the city, end the day with 46500wh
Approximately 7pm to 7am charging at 1440w to add 17280wh overnight.

Tuesday: Start the day with 63780wh. That's only a deficit of 3720wh. That's less than 3 hour of charging that I'm behind. End with 47580wh.
Wednesday: Start with 60060wh. End with 39060wh.
Thursday: Start with 56340wh. End with 35340wh.
Friday: Start with 52620wh. End with 31620wh.

I would need 25 hours over the weekend to get back up to 90% SOC by Monday morning.

If I drive more conservatively (boring!) then obviously there's more energy left in the battery for "running errands" and such.

If I lived in an area with more inner city Superchargers, or even CCS, I'd probably be fine with it. But there are occasions where I need to drive substantially more than just my predictable commute and Arkansas has crappy options for a quick charge.

I guess what I'm getting at is, if you really want high amp charging at home that's fine. But I'd be willing to bet you could get by with a 15 amp circuit. Especially if you have Superchargers in your city.

 

[Harriscott]

120V@15A suffices, adding 40 miles (or more) of range overnight. But evenings out or running errands can create a deficit that takes days to recover.

I did this for over a year, then spouse had a 240V installed and happiness increased. It unleashed the car and we could return from a long trip at low SOC without worry.

 

[OldEVDude]

The short answer is that yes, you can.

When I took delivery of my MPLR, my electrician was backed up (and just left on vacation). So for a month 15A was all I had. I could get about 60 miles of range on an overnight charge, and I would rarely drive more than 60 miles in each day. No problem.

Where you see the difference is when you get home from a long trip. When you roll into the garage with a 10% SOC, by the next morning the car will only be around 40%. The solution is to stop at a Supercharger before going home. Fortunately, there is a Supercharger about seven miles away. Annoying (when you are tired from all that travelling), but doable.

I went ahead and got the 30A circuit and I'm not sorry I did. Still, if I had a house that couldn't support a 30A circuit, I could live with just 15A.

 

[E90alex]

It’s totally doable, but if you stray from your normal routine or drive a lot over the weekend then it will be hard to catch back up without easy access to a faster charger.

120v charging is also less efficient because there is a certain amount of baseline draw while the car is charging since the electronics and cooling systems are on and active (about 250-300W per hour).

240v charging will finish charging faster so the car can turn off and go to sleep.

For example on 120v the car will be on and drawing up to an additional 3600W over 12 hours, whereas on 240v the car may only need to be on for 2-3 hours and use an additional 600-900W.

But if 120v works for you, then by all means keep using it.

 

[EVSince2011]

I have a friend with a 2019 M3. He has charged it at home on 120 for 3 years. It works for his daily driving of 30 to 40 miles. We have had 2 EV's since 2013. For a long time we charged a 2013 Leaf on 120. We now have two 240 stations, a Wall Connector for our 2018 M3 and a GE J1772 for our 2014 Leaf. More flexible than 120, but we could handle most of our charging ok on 220.

 

[EVSince2011]

I have a friend with a 2019 M3. He has charged it at home on 120 for 3 years. It works for his daily driving of 30 to 40 miles. We have had 2 EV's since 2013. For a long time we charged a 2013 Leaf on 120. We now have two 240 stations, a Wall Connector for our 2018 M3 and a GE J1772 for our 2014 Leaf. More flexible than 120, but we could handle most of our charging ok on 220.

That's 120, not 220.

 

[Sophias_dad]

Don't forget the in-between land of a 20A/120V outlet. Its not all that uncommon for electricians to use only 15A outlets even on 20A circuits. I suspect they are just being cheap, and the electrical code allows it because(presumably) they expect several 15A outlets on a single 20A circuit.

You would have to buy another adapter for the UMC(and maybe change the outlet if its not already 20A), but that's MUCH cheaper than a new circuit. This presumes there's already a 20A breaker and 12 gauge wiring, of course.

 

[E90alex]

Don't forget the in-between land of a 20A/120V outlet. Its not all that uncommon for electricians to use only 15A outlets even on 20A circuits. I suspect they are just being cheap, and the electrical code allows it because(presumably) they expect several 15A outlets on a single 20A circuit.

You would have to buy another adapter for the UMC(and maybe change the outlet if it’s not already 20A), but that's MUCH cheaper than a new circuit. This presumes there's already a 20A breaker and 12 gauge wiring, of course.

120v 20A circuits are typically used on a house just so you can run more devices on the same circuit and/or heavier load devices. Not necessarily to run devices with a 5-20 plug, which are very uncommon in the household so usually no need to use 5-20 receptacles.

If you do want to install a 5-20 receptacle on a 20A circuit, then make sure there are no other devices using that circuit because EV charging will essentially max it out and using other devices on that circuit at the same time can overload it and trip the breaker.

And if it’s already a dedicated 5-20 circuit with just one outlet, might as well convert it to a dedicated 6-20 240v circuit instead.

 

[johnny_cakes]

I did 120V for about a month, and while it's better than having to rely on public chargers, it required planning and caused some anxiety. Enough so that it was worth installing a 240V outlet in my garage. As a bonus, I saw my charge efficiency go from 85% to 95%:

 

[LoudMusic]

I did 120V for about a month, and while it's better than having to rely on public chargers, it required planning and caused some anxiety. Enough so that it was worth installing a 240V outlet in my garage. As a bonus, I saw my charge efficiency go from 85% to 95%:

The anxiety is actually a really big component I think. And is why so many people are resistant to buying an EV in the first place. I think it's because they're not good planners

 

[ucmndd]

The anxiety is actually a really big component I think. And is why so many people are resistant to buying an EV in the first place. I think it's because they're not good planners

Who wants to spend time actively planning whether or not they’ll have the energy necessary to drive somewhere when they need to?

Unless you don’t own your home or the costs are wildly prohibitive, I can’t imagine why any EV owner would NOT install some sort of L2 charging.

 

[father_of_6]

I think the answer for a lot of people is "No"... you can't get by on 15A charging. Sure, it works and you might be able to make it work for you some, most, or even all of the time.

If it's 12°F outside and you park outdoors, 15A charging will be woefully insufficient. It's likely that it won't be able to warm up the battery enough to actually charge. Or you'll wake up with *much* less than you expect.

 

[EfficientWatts]

I think the answer for a lot of people is "No"... you can't get by on 15A charging. Sure, it works and you might be able to make it work for you some, most, or even all of the time.

If it's 12°F outside and you park outdoors, 15A charging will be woefully insufficient. It's likely that it won't be able to warm up the battery enough to actually charge. Or you'll wake up with *much* less than you expect.

It does really depend. Obviously for you living up north 120V in the winter won't cut it. However more down south 120V probably would be perfectly fine, and then of course there's superchargers.

The situation is going to vary from person to person, and they'll have to take stock (driving habits/patterns, weathers, etc). The more variables, range, and questions one has, the less likely one could get by on 120V IMO.

 

[ucmndd]

It does really depend. Obviously for you living up north 120V in the winter won't cut it. However more down south 120V probably would be perfectly fine, and then of course there's superchargers.

The situation is going to vary from person to person, and they'll have to take stock (driving habits/patterns, weathers, etc). The more variables, range, and questions one has, the less likely one could get by on 120V IMO.

Why did you disagree with his post and then restate the points he made nearly verbatim?

 

[SageBrush]

But is it even necessary? Can we survive on a 15A outlet?

Who is "we" ?

I put in a higher power circuit for a couple of reasons, and I'm glad I did:

1. As mentioned by others, pre-conditioning
2. Much higher efficiency. L1 charging sends about 1.15 kW net of the 1.44 kW metered energy to the battery
3. I like the flexibility of being able to put substantial energy into the battery in the morning, either because I am topping off before a trip or because I forgot to plug in
4. The higher power circuit lets me self-consume my PV of up to 7 kW. For other people it is a matter charging in certain time windows, e.g. to take advantage of lower rates or when the energy is clean.

EVs will "survive" on L1. They will not starve. Whether they will be happy is a YMMV

 

[ATPMSD]

Yes of course you can get away with 120v/15a charging, provided you can live within the limitations. But here is the thing, people spend a ton of money buying their Tesla and then cheap out on charging it. I know people will argue that adding a 240v circuit is a waste of money if you do not need it, but who needs a Tesla?

Spend the money to put in a good 240v circuit and enjoy the car instead of planning your daily charging.

 

[ItsNotAboutTheMoney]

Yes of course you can get away with 120v/15a charging, provided you can live within the limitations. But here is the thing, people spend a ton of money buying their Tesla and then cheap out on charging it. I know people will argue that adding a 240v circuit is a waste of money if you do not need it, but who needs a Tesla?

Spend the money to put in a good 240v circuit and enjoy the car instead of planning your daily charging.

People with 15A aren't necessarily doing any planning. Lots of people have relatively short commutes so a 12A circuit gives them comfortably more than enough.

Also, depending on the model, Teslas may simply be a decision to buy an electric vehicle in which they can travel long distance. As far as EVs with good DCFC, Tesla have not been a particularly expensive choice, aside from the post-COVID price gouging period.

For many people it could be better to wait until they are thinking about plug-in 2 or other changes.

 

[jeremymc7]

Been rocking 15A for years on two cars and work great. If you work 16 hour days 200 miles away you’ll likely need something faster.

But I’m many cases “managed” charged with a household outlet will work for most people.

You can also look at the wiring being the house. Many installers use 20A wire for 15A amp breakers and outlets. Swap the outlet and breaker and toy have faster charging.

If you have the money and it’s disposable why even question what do you. If you don’t have the money and you don’t drive 300 miles each day then stock 15A charging will be fine.

 

[SageBrush]

You can also look at the wiring being the house. Many installers use 20A wire for 15A amp breakers and outlets.

If the branch circuit is not dedicated, the EV should probably charge at 8 Amps. Then you are talking about ~ .67 kW NET into battery, good for 2 - 3 miles of range per charging hour

 

[jeremymc7]

The one I use is not dedicated but I either don’t use anything else on it and charge at 12A/5m; or I f I need to charge anything else I drop it to 5-8A depending and still get about 3M.

Totally usable depending on your willingness to monitor (which becomes second answer) and driving demands.