Assumptions for future proofing for residential electric car

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marmathsen

Senior Member
Location
Seattle, Wa ...ish
Occupation
Electrical Contractor
In a residence, when submitting a bid, or doing calculations, or submitting a service application, what size do you assume for a FUTURE electric car charger? or multiple cars?

Tesla's wall charger used to be able to supply 80A max at 240V, but now it is only rated for 48A. I thought Porsche was going to offer a high capacity home charger but theirs looks like it's only 40A max.

Are there any HOME chargers that exceed 48A? Do you assume load sharing if there might be multiple cars?

Rob
 
Assu;me a standby generator!
Once nearly EVERBODY has an electric care in the FUTURE expect the grid to collapse quite often - unless fusion power becomes a reality.
I wasn't around, but I don't recall hearing about that happening when motors, air conditioning, electric heat, and suburbs happened. I'm pretty sure it will be just fine.
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
However, back then pocos could build a new fission and coal plants, or dam another river.
Sun does not shine at night when 400 million cars on charge and wind is variable?

Worked for CWL&P (Spfld, IL) in 1966, town of only about 100,000 then, they added 68 MW coal plant in 1968 and another in 1972 and think they have added another 400 MW coal and gas since then. Only the wealthy had AC there until late 60s. No way they can build more coal plants.

People scared of nukes, coal is now evil, NY just recently outlawed new gas plant. So, where is all the electric vehicle power going to come from, every body switching to LED lights? /s/

Tacoma power started planning for dams on the Cowlitz river in 1946, delayed even then by salmon advocates and 'greenies' until 1960s. Added nearly 400 MW to NW area power grid.

That is why I added the fusion power qualifier, everything else either will kill us by radiation, destroy wildlife and fish, add CO2 to flood the coasts, etc. etc.... Only other possibility is if CO2 sequestering is somehow figure out?
 
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augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I'm surprised that Art 220 hasn't added a 50 amp EV circuit to the minimum required circuits.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Engineer
... Are there any HOME chargers that exceed 48A? Do you assume load sharing if there might be multiple cars? ...
If the intent is future-proofing, planning for multiple and higher-capacity chargers seems wise. Upsizing the conduit to the garage (without immediately upsizing the conductors) doesn't add much to the initial cost.

... Once nearly [EVERYBODY] has an electric [car] in the FUTURE expect the grid to collapse quite often - unless fusion power becomes a reality. ...
The implementation of fusion power -- which is about eight or ten years away, and has been eight or ten years away ever since November 1, 1952 -- will have no effect on transmission & distribution capacity.

Electric-vehicle chargers will be installed one at a time. The grid will be upgraded one branch circuit at a time. We will be more-or-less okay.

The smart grid (Internet of Things) is also coming. It will greatly reduce the need for spinning reserve and greatly reduce the likelihood of a large-scale grid collapse by selectively shedding loads. There is probably nothing more interruptible than battery charging -- it can switch off ¹/₆₀ of a second after getting a request. Air conditioning can be interrupted for ten or fifteen minutes without anybody noticing. (and smart thermostats can reduce the indoor temperature by a degree or two when the smart grid tells them that power's abundant) Likewise electric space heating. Water heating could be interrupted all night with the installation of a day's worth of storage.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
If the intent is future-proofing, planning for multiple and higher-capacity chargers seems wise. Upsizing the conduit to the garage (without immediately upsizing the conductors) doesn't add much to the initial cost.


The implementation of fusion power -- which is about eight or ten years away, and has been eight or ten years away ever since November 1, 1952 -- will have no effect on transmission & distribution capacity.

Electric-vehicle chargers will be installed one at a time. The grid will be upgraded one branch circuit at a time. We will be more-or-less okay.

The smart grid (Internet of Things) is also coming. It will greatly reduce the need for spinning reserve and greatly reduce the likelihood of a large-scale grid collapse by selectively shedding loads. There is probably nothing more interruptible than battery charging -- it can switch off ¹/₆₀ of a second after getting a request. Air conditioning can be interrupted for ten or fifteen minutes without anybody noticing. (and smart thermostats can reduce the indoor temperature by a degree or two when the smart grid tells them that power's abundant) Likewise electric space heating. Water heating could be interrupted all night with the installation of a day's worth of storage.
So, the solution to future electricity demand isn't to build a robust grid capable of supplying all the power needed at any time, but to kludge ad hoc control units onto the grid so operators can frantically turn off their customers for variable and unpredictable intervals to keep the grid from collapsing. Welcome to Nigeria.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Engineer
... kludge ad-hoc control units onto the grid so operators can frantically turn off their customers for variable and unpredictable intervals to keep the grid from collapsing. ...
That's what we have right now, with hundreds of independent utility corporations & cooperatives, each with their own tariffs, rules & strategies and little or no central planning.

To build a grid/generation network that can supply everybody's whims every second of the year would be hugely expensive. It would be a lot smarter to recognize that different kinds of consumption have different levels of immediacy and capitalize on that.
 

cpickett

Senior Member
Location
Western Maryland
Occupation
Electrical Engineer
That's what we have right now, with hundreds of independent utility corporations & cooperatives, each with their own tariffs, rules & strategies and little or no central planning.

To build a grid/generation network that can supply everybody's whims every second of the year would be hugely expensive. It would be a lot smarter to recognize that different kinds of consumption have different levels of immediacy and capitalize on that.
I think grid storage will become more necessary to smooth out the transients in between switching events, and for those times where you can't shed enough load fast enough. Will be interesting to see what happens over the next 10 years. Solar fields and panels on houses are being put everywhere as fast as they can build the panels, that will only strain the grid further.
 

marmathsen

Senior Member
Location
Seattle, Wa ...ish
Occupation
Electrical Contractor
Guys, the grid will continue to be improved and upgraded just like it always has. Calm down.
Exactly!

This whole transition won't happen over night. The demands on the grid and upgrading of the infrastructure will happen in tandem...as it always has.

Sent from my Pixel 4 XL using Tapatalk
 

rszimm

Member
Location
Tucson, AZ
I've gone through this. I think you're looking at this based on the demands of the charger rather than the amount of power you truly need to supply. Let's make some assumptions...
1. You have a 40 mile commute every day each direction. (80 miles total)
2. Your spouse also has a 40 mile commute every day each direction. (80 miles total)
3. You have two kids with their own cars. They each drive them 10 miles per day.

So, this is 180 miles per day that you have to replenish. Lets just round it up to 200 miles/day. (that's an insanely high number BTW... much much higher than the average commute)

Next set of assumptions:
A. You have 9 hours to recharge all of this overnight (8 hours to sleep, 1 hour to eat dinner and get ready in the morning)
B. Electric cars require 24 kWh/100miles. (a typical Tesla model 3)
C. You're using smart chargers (this is important...more on this later).

So, to recharge your full 200 miles, you need 48kWh of power. If you have 9 hours to do it, and 240V circuit, you need 22A total. Round up to a 30A circuit.

That's it. It doesn't matter if the Tesla charger of the future will use 100A, 200A or whatever. You don't care. A 30A circuit will easily recharge 200miles over the course of a 9 hour period.

Assumption C is important. It assumes smart chargers that know the circuit capacity (30A in this case), and can talk to all the other chargers attached to the same circuit to make sure none of them exceed 30A. The high end chargers already do this. Furthermore, the manufacturers are working on standards whereby any manufacturer's charger will be able to talk to any other manufacturers to share power like this. So I think it's a reasonable assumption that smart chargers are going to be the future.

Also note that only having 9 hours to recharge is unlikely. I say that most people have more like 12 hours at home every evening/morning to recharge. Furthermore, 24kWh/100m is what TODAYs cars get.. They're likely to get more efficient as time goes on. And finally, this assumes you only recharge at home, whereas more and more offices/schools/etc are starting to put in chargers.
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
Exactly!

This whole transition won't happen over night. The demands on the grid and upgrading of the infrastructure will happen in tandem...as it always has.

Sent from my Pixel 4 XL using Tapatalk
Extrapolate the 20 year no growth scenario since Y2K: Now add in the pre-mentioned 24 kWHrs/day x say 50 million cars being charged x say 365 days = about 'only' 10% capacity increase needed.
However, consider non-technical issues (e.g politics and global warming, ecology , etc).
Graph at least stayed flat due to fracking (which is being badmouthed nowadays) and NG. NY and others** recently restricted NG power plants and coal will zero out. Minimal growth needed the last 20 years due to efficiency expenditures (e.g PSE paid for my HPWH)

**
https://cleantechnica.com/2021/03/0...-hookups-in-new-buildings-cancelgas-electrifyeverything/

10% seems trivial, but solar/wind do not seem able to supply that especially if the coal and NG (and nuclear) generation segments are eliminated! e.g > 80% of existing generation slated for elimination?

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marmathsen

Senior Member
Location
Seattle, Wa ...ish
Occupation
Electrical Contractor
Extrapolate the 20 year no growth scenario since Y2K: Now add in the pre-mentioned 24 kWHrs/day x say 50 million cars being charged x say 365 days = about 'only' 10% capacity increase needed.
However, consider non-technical issues (e.g politics and global warming, ecology , etc).
Graph at least stayed flat due to fracking (which is being badmouthed nowadays) and NG. NY and others** recently restricted NG power plants and coal will zero out. Minimal growth needed the last 20 years due to efficiency expenditures (e.g PSE paid for my HPWH)

**
https://cleantechnica.com/2021/03/0...-hookups-in-new-buildings-cancelgas-electrifyeverything/

10% seems trivial, but solar/wind do not seem able to supply that especially if the coal and NG (and nuclear) generation segments are eliminated! e.g > 80% of existing generation slated for elimination?

View attachment 2557672
Well you certainly have thought more about this than I have.

I'm hoping that the market will see the glut in the supply and a better solution will come about than simply installing generators everywhere. Nuclear seems like a good option here but I know traditional reactors have unfortunately long permit and build times. Although if I'm not mistaken aren't the more recent generations of reactors able to be built quicker?

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GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
I'm surprised that Art 220 hasn't added a 50 amp EV circuit to the minimum required circuits.
[SARCASM to situation, not Gus; he was probably sarcastic in his reply too?] and enclosed garages with this circuit for all homes, condos, and apartments? Will mobile homes be exempt?[/SARCASM]
 
Location
Canada
Occupation
Electrical E.I.T
Assu;me a standby generator!
Once nearly EVERBODY has an electric care in the FUTURE expect the grid to collapse quite often - unless fusion power becomes a reality.
And I thought I was the only one wondering about the future failures, as people around me think EVs are the only future and I agreed but at what cost? I don't know much about how the grid is doing as of now but being an analytical geek, if we need all EVs by 2035, we might need to take steps to upgrade the grid from the very moment! Also, Smart grids might be the solution but still for more lithium we need more mine site to dug it out, again affecting atmosphere!

I really like it by seeing people being more realistic than optimistic! I would love to know more about it! Please check your DM junkhound.
Junkhound+1
 
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