Demand factor for multiple car charging station

[babool]

Does anyone know the demand factor used to calculate the service size for multiple car charging stations, 10-20 unit range?

 

[Dennis Alwon]

As far as I know there isn't a demand factor stated in art. 220-- Since they are all likely to be on at the same time I wouldn't expect a demand factor either.

 

[augie47]

I don't disagree but can't help but think of the multiple charging stations we have in this area with underbrush now growing in some of the charging spots. Another year, the only way all spots will be in use is if someone brings a chain-saw.

 

[JFletcher]

I have no experience nor NEC knowledge of your setup however, as a practical means:

~~ some a hole will double park his minivan or sports car, relegating two of those spaces into paperweights.

~~ three people will illegally park there. They do not have electric vehicles.

~~ with the 5 of 10 of remaining spaces, you might actually get 5 electric vehicles that need to charge all at the same time.

 

[SSDriver]

Around here there are a few places that have about 5-10 car charges all going at once and people waiting to park in those spots. I personally would size it assuming at some point they will be running at the same time and for a long time. What type of facility is it? That can make a big difference. Some of the schools here have 10 or so charging stations, all of the teachers show up at the same time in the morning and plug their cars in. So until lunch or the cars are charged, they are all going at the same time.

 

[retirede]

I have no experience nor NEC knowledge of your setup however, as a practical means:

~~ some a hole will double park his minivan or sports car, relegating two of those spaces into paperweights.

~~ three people will illegally park there. They do not have electric vehicles.

~~ with the 5 of 10 of remaining spaces, you might actually get 5 electric vehicles that need to charge all at the same time.

I’ve only seen EV charging parking places in private lots - large companies, airports, etc. No evidence of those issues you mention.

Now if it were public parking (shopping mall or such) I suspect you would see those issues.

 

[babool]

babool

babool

Thanks guys, i'm going to go with full load, it's on an Air Force base and likely they could all be in use at the same time , (10) 32 amp units to one panel and (18) 32 amp units to another, all single phase, 240v.

 

[ron]

There are so few demand factors available in the Article 220 calculations, that is why services are conservatively sized.

 

[Besoeker]

I don't disagree but can't help but think of the multiple charging stations we have in this area with underbrush now growing in some of the charging spots. Another year, the only way all spots will be in use is if someone brings a chain-saw.

I agree.
And I have a feeling that might be the case for some time. The uptake of EVs is a long way off being mainstream.
Range and recharge times are still limitations.
"With a maximum range of up to 107 miles," - Nissan Leaf.
And a 40kWh battery exceeds average daily domestic energy use by some margin.

 

[petersonra]

I suspect there are no such factors available. I think the reason is that they could all be in use at the same time even though they are rarely used at all, at least around here.

 

[Besoeker]

I suspect there are no such factors available. I think the reason is that they could all be in use at the same time even though they are rarely used at all, at least around here.

As I said, I think that will remain so - at least in the near future.
I wonder if anyone on this forum actually has a road going EV?
I don't know anyone who has.

We, UK, had milk floats. They delivered milk to your doorstep (in glass bottles) in the early hours. A British icon.
Their merit was that they were slow, quiet, suited the stop-start nature of the task, had a defined, limited route after which they returned to base for the rest of the day to recharge. In short, not regular motoring as we know it.

 

[petersonra]

the problem with electric cars has always been the recharge cycle.

basically a gallon of gas has 100,000 btus in it. at 33% efficiency it is about 10 kwH of useful energy at the wheels.

to get 10 kwH out of a 230V wall socket takes almost an hour at almost 50 Amps.

 

[Besoeker]

the problem with electric cars has always been the recharge cycle.

basically a gallon of gas has 100,000 btus in it. at 33% efficiency it is about 10 kwH of useful energy at the wheels.

to get 10 kwH out of a 230V wall socket takes almost an hour at almost 50 Amps.

And they are rated at 13A here.

 

[petersonra]

And they are rated at 13A here.

13A X 230V = a little less than 3 kw-hr per hour. Or about the equivalent of < 1/3 gallon of gas.

 

[Besoeker]

13A X 230V = a little less than 3 kw-hr per hour. Or about the equivalent of < 1/3 gallon of gas.

Kinda puts it in perspective when you have a 40kWh to charge.

 

[petersonra]

Kinda puts it in perspective when you have a 40kWh to charge.

It is almost like they want electric cars to fail if this is the best charging option available.

Tesla has a 73 kw charger option for one of its cars. but it takes 70 + Amps at 240V. Not very many dwellings have that kind of service capability left over.

 

[Besoeker]

It is almost like they want electric cars to fail if this is the best charging option available.

Tesla has a 73 kw charger option for one of its cars. but it takes 70 + Amps at 240V. Not very many dwellings have that kind of service capability left over.

Around 300A I think
But there is another, perhaps more serious, consideration here.
If most people went for EVs the whole electrical infrastructure would have to be upgraded. Generation, transmission, distribution at all levels.
This is an issue seldom confronted by those who promote the merits of EVs.

Please understand that I'm not anti EVs and the prospect of reduced pollution. I just think we need to look at the whole picture.

 

[wwhitney]

My household only has electric cars. Charging occurs at home overnight, so we never have to visit a gas station. Trips over 200 miles require advance planning and finding a quick charger. As we rarely make such trips, the net result is that we spend less time per year on refueling than we would with a gas car.

Cheers, Wayne

 

[hbiss]

Around 300A I think
But there is another, perhaps more serious, consideration here.
If most people went for EVs the whole electrical infrastructure would have to be upgraded. Generation, transmission, distribution at all levels.
This is an issue seldom confronted by those who promote the merits of EVs.

Please understand that I'm not anti EVs and the prospect of reduced pollution. I just think we need to look at the whole picture.

Most people who buy EVs do it for the advantage of not paying the taxes that are tacked onto gasoline and diesel fuels. I can guarantee you that that will change if EVs become popular enough to put a dent in the road use and other taxes. Government is very good at taxing things and I can see an EV tax and a mileage tax.

As for upgrading the infrastructure, I've talked about that before. Tax the cause which is the EV owners. Tax on ownership and higher rates for the power used to charge them to help pay for infrastructure upgrades. Why should everybody else underwrite the cost of infrastructure upgrades because of EV owners trying to cheat the system to save money.

Once the government taxes the crap out of them to pay for their use we will see who the environmentalists are that still buy them. Betcha not enough to make EVs such a good idea anymore. :bye:

-Hal

 

[wwhitney]

Most people who buy EVs do it for the advantage of not paying the taxes that are tacked onto gasoline and diesel fuels. I can guarantee you that that will change if EVs become popular enough to put a dent in the road use and other taxes. Government is very good at taxing things and I can see an EV tax and a mileage tax.

Taxing EVs for their externalities is appropriate if we also tax gasoline cars for their externalities, i.e. air pollution. Until that happens, providing subsidies like the federal tax credit and reduced taxes on EVs is an another way to address the problem.

Cheers, Wayne