How much power to the garage?

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danickstr

Senior Member
There are apparently two current standards regarding the future charging of vehicles:

IEC 62196 and SAE J1772

One can go up to 70 amps 220 and the other can apparently suck up to 250 A a/c and 400 A d/c ---WOW.


Any thoughts on this from the engineers?
 

MJJBEE

Member
Whatever you do it will be wrong

Whatever you do it will be wrong

I think this will be Vehicle dependent and I wouldn't worry about it and retrofit in 10-15 years when electric vehicles become more prevalent. If you have a customer who is buying an electric car they can add the charging infrastructure then. just my 2 cents
 

danickstr

Senior Member
the current customer claims he will be buying a Chevy Volt in 2010. It uses the 1772 plug at max 70a 240 I didn't know if the Volt would pull that, or if someone has 2 volts, will they need a 200A service for the garage? thnks for the link.
 

iwire

Moderator
Staff member
Location
Massachusetts
I would not worry to much about it, the utilities will not be able to supply the power to charge a neighborhood full of electric cars without a lot of infrastructure upgrades.
 
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dbuckley

Senior Member
The (I think it is proposed) European standard for car charging uses a connector that can carry 32A at 400V three phase for charging. So about 20KW. But the whole system is intelligent in that the source tells the car what it can provide, so if all you have available is 10A at 240V (just over 2KW) then that is what the car will limit itself to. So the charging time depends on the power available.

I'd be amazed if the American standard doesn't work the same way.

But if you want to fast charge two cars then you are going to need a lot of power...
 

danickstr

Senior Member
Another electrician I was talking to also pointed out that here in WA there is 100 million sitting around for use to implement city charging stations. I don;t know if it carries over to rebates for homeowners. But since most people won't buy one right away (bleeding edge will cut you) I guess the POCO has time to upgrade their stuff.
 
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GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
I would not worry to much about it, the utilities will not be able to supply the power to charge a neighborhood full of electric cars without a lot of infrastructure upgrades.
As I remember reading, there is a "car charging" rate structure planned, and the utility will have dynamic control over how much can go into the charger. It is hoped that most will occur in low usage time. The article I read (forget where, sorry) mentioned that the user could override the limit and pay more for the power. And as others mentioned, the chargers are planned to be settable for a maximum ... if there is only 30A available, that is all it will use.

NEC will have to address this ... 70 amp outlet on 20 amp circuit ...
 

iwire

Moderator
Staff member
Location
Massachusetts
The article I read (forget where, sorry) mentioned that the user could override the limit and pay more for the power.

It will not mater the rate, the existing infrastructure can only handle a certain amount of load.

In my area power companies offer huge incentives to reduce the load on the system.

Some of our commercial customers with generators have had equipment installed by the utility that allows the power company to remotely start the generators and make the transfer switch operate to shed load off of the grid at times of high load.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
I'd like to see the numbers (I don't know them), but the story that I've always heard is that while the existing infrastructure is getting pretty cramped at peak usage times, that there is plenty of excess capacity at low usage times, eg. during overnight hours.

If this is the case, then chargers which are used mostly during low demand times won't require much in the way of additional infrastructure capacity. The question is then: what sort of smarts will the chargers have in order to limit usage to these presumed low usage times?

On the original question: the numbers that I've heard for the Chevy Volt are a 16KWh nominal capacity battery pack which will be limited to 8KWh usage at any one discharge, in order to get long battery life. So figure that you'll need to dump about 10KWh into that battery to charge it. If you want to 'gas up' at a 'station', then even a 20KW charger would be too slow. (Could you imagine spending a half hour at the 'pump'???

For charging at a car park while you are shopping, 20KW would be good, at least with valet parking. But for charging at home overnight, a single 15A 120V circuit would have enough power to get the job done.

-Jon
 

active1

Senior Member
Location
Las Vegas
The SAE J1772 is more than a cord cap. It's called a coupling (625.16).
It is part of some new standards that will come with the electric car. Part of the above is SAE J2847/J2836 Communications Standard (comunications over power lines) for electric cars.

Follow the link to what looks like a GM training documents overviewing the Volt electric car:

http://www.ieso.ca/imoweb/pubs/smart_grid/GM-TomOdell.pdf

From Page 16:

NEC Article 625
Comettee work underway
Replacent of terminaligy "charging" with "power transfer" to recognize potential of an EV as a source of power.

Look at 625.26 Interactive Systems
Electric vehicle supply equipment ..... also serve as an optional stanby system or an electric power source. Article 702 or 705 shall apply.

To sum it up it with this tecnoligy in place it looks like to me:
The utility will be able to adjust your car charger to adjust for their grid load
The utility may be able to use the EV to backfeed the grid
The utility will be able to charge different rates for EV and different times of day
Their may be plans for a road tax on the EV electricity used
The EV owner could be identified for billing puposes at an other than home location (roaming) within the same utility operator
The utility can identify the type of location that is charging the EV

Perhapse stolen EV or their drivers could be located when pluged in with this tecnoligy
 

danickstr

Senior Member
it only goes 40 miles on a charge, so you would be in need of a charge if you come home at lunch. Hope POCO lets you plug it in.
 

active1

Senior Member
Location
Las Vegas
I can hear it now. Who will they call? The auto mechanic, electrician, or utility?
"My EV does not charge during the day".
"It charged in no time until everyone elce on my street got one".
"The batteries have less power after I plug it in sometimes"
"no car in my neighborhood will start after a night of sevier weather"

Can just picture when so many have EV's and there is a large scale power outage lake the Northeast blackout of 2003. Every EV pluged in would be dead reguardless of batery level.

Sounds like this system would be a deal breaker for the all EV. Or at least a foot note in their development saying something like "when EV first gained popularity they had charging problems because the utility system was undersized for all the new cars".

The duel power gas engine & battery EV's would still work. At that point your driving around running off a gasoline generator. I wouldn't think that would the most efficent system. Although locomotives do it with diesel. Except they don't have batteries in the loop and the engine / generator is designed to provide full power.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
I am going to prewire a residential garage for electric vehicle use - I figured a 3/4" EMT to would cover it. Now I'm starting to wonder if that's big enough...?
 

broadgage

Senior Member
Location
London, England
it only goes 40 miles on a charge, so you would be in need of a charge if you come home at lunch. Hope POCO lets you plug it in.

I dont see why they would stop you, anymore than they would stop you running the A/C or the water heater.
It is likely though that time of day pricing would make daytime charging a lot more expensive than night time cgarging.
This would also encourage the consumer to shift other loads to the off peak hours.

The proposed standard for charging E/Vs contains a number of sophisticated features whereby the charging input can be limited to the available supply, or restricted and controlled in various other ways.
This would, for example allow the utility to interupt charging briefy in the event of unexpected shortage of power.

However the present lightweight electric vehicles used in London have no such sophistication. They are simply plugged into a standard 13 amp or 16 amp 230/240 volt single phase outlet.
For indoor charging, a standard outlet as already installed in most garages is suitable.
For outdoor charging a similar but weatherproof outlet is needed.
The utility does not "know" if the load is an EV or say a space heater.
 

active1

Senior Member
Location
Las Vegas
I dont see why they would stop you, anymore than they would stop you running the A/C or the water heater.

Having the utility control your AC is an option for many people.

http://www.comed.com/homesavings/programsincentives/accycling.htm
You get a total of $40 if you let the utility turn off your AC for 3 hours a weekday between 11am-8pm.

http://www.coolshareprogram.com/?site=res
They change your thermostat to one that is controlled via the utility network. You can override it but then it defeats the small credit for having the system.

Utility controled water heaters:
http://www.marathonheaters.com/utilities.html

They have plans for all the major appliances:

GE plans to be the first manufacturer to offer a full suite of demand response appliances that will work with utility smart meters to help shed load from the grid, while helping consumers save money during peak demand usage and pricing times. GE appliances and products will work with smart meters to delay or reduce energy use without major interruption to consumer?s lifestyles by giving the consumer control over their energy use.
http://www.genewscenter.com/content/Detail.asp?ReleaseID=7272&NewsAreaID=2



However the present lightweight electric vehicles used in London have no such sophistication. They are simply plugged into a standard 13 amp or 16 amp 230/240 volt single phase outlet.

Micro cars are not so pupular here yet. I know of one new Smart car was used as a prank prize. The funniest one was a smart car with a 3' tall Elvis impersonator in front of it.
 
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