Demand factor for multiple car charging station

[ramsy]

Fodder for more Tax cannons, to offset Medical Cost of smog-belching vehicles.

Evidence mounts for Alzheimer's, suicide risks among youth in polluted cities
https://medicalxpress.com/news/2018-04-evidence-mounts-alzheimer-suicide-youth.html

Already addressing the solution, Toyota, Nissan, Honda, Hyundai, Mercedes, Ford & others produce Fuel Cell Electric Vehicles reforming E100 Ethanol. The FCEV widely used in Brazil chemically reforms E100 to electricity, with similar energy density & range to internal-combustion vehicles, and similar fill up time. These FCEV's currently can't reform E85 Ethanol sold at filling stations in North American for Flex-Fuel internal combustion engines only.

Pure Hydrogen filling stations and vehicles also exist, but are not widely available in North America.

 

[Besoeker]

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

Except you are refuelling for several hours overnight.
Takes me about 10 minutes to fill up. And I can do about 800 miles on that.

 

[wwhitney]

Except you are refuelling for several hours overnight.
Takes me about 10 minutes to fill up. And I can do about 800 miles on that.

The car is refueling overnight, but I spend about 30 seconds plugging it in. That's less time for me dealing with refueling.

I agree that if I regularly wanted to drive 800 miles, I'd want a different car.

Cheers, Wayne

 

[Ingenieur]

some states have adopted (modified/clarified) the nec
http://www.oregon.gov/bcd/codes-sta...hods/sam-09-01-calcelectricalvehiclecharg.pdf

they do not consider them a continuous load
nor operate at rated flc (they consider it a peak that taprs off, so avg is lower)
allow for a demand factor, in this case 10-20 units ~70-80%

 

[drcampbell]

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

Perhaps, but you can't design the wiring for the typical case. you have to design it for the worst case.

... 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. ...

A typical gasoline engine in an automobile achieve about 7% thermal efficiency. 30-plus% efficiency is the domain of coal-fired powerplants that run at a consistently high temperatures and high loading - no cold starts, stop-start, using a 200-Hp engine to provide 20 Hp or idling. Even base-loaded nuclear powerplants seldom achieve 33% thermal efficiency due to metallurgical temperature limits.

 

[Ingenieur]

7% seems low for a gasoline engine
iirc 25-40% depending on comp ratio, fuel delivery method, turbo, etc

 

[hbiss]

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

So we are all supposed to pay for other peoples EVs through subsidies and reduced taxes on them? Then you equate gasoline cars' air pollution with the enormous cost of upgrading our electrical infrastructure? Spoken like a true Californian.

Has anybody considered where our electric comes from? How much of it now comes from fossil fuel and at what cost in air pollution? If we have to increase our capacity two or three fold what are we supposed to build? Oh, I know. You Californians envision windmills and solar to make up the demand. The reality is that increased generation is going to negate any reduction in air pollution that EVs claim.

-Hal

 

[Besoeker]

The car is refueling overnight, but I spend about 30 seconds plugging it in.

Yes, but refuelling for quite a long time nevertheless. And time when the vehicle is out of commission.
That's OK if your lifestyle suits that and your journeys are relatively short.

 

[Ingenieur]

gasoline cars are taxed by fuel taxation used for road maint/construction
ev's are not, yet they use the roads (they do pay taxes on power though)
isn't that enough of a tax break?

 

[wwhitney]

Yes, but refuelling for quite a long time nevertheless. And time when the vehicle is out of commission.
That's OK if your lifestyle suits that and your journeys are relatively short.

Since I don't drive while I sleep, it's fine that the car is out of commission overnight.

Range-wise, a modern 200+ mile EV will be suitable depending on the frequency of driving more than 200 miles in one day and willingness to deal with the concordant planning. If you never drive more than 200 miles in a day, then no problem. If you do it once a month, then either you have to do the requisite planning or use a different car that day (if available). If you do it every day, I wouldn't recommend an EV.

Cheers, Wayne

 

[wwhitney]

So we are all supposed to pay for other peoples EVs through subsidies and reduced taxes on them?

What would be best is that each person pay for the costs of their own actions. With that as a baseline, gas cars get a subsidy by not being charged for their air pollution, and because of the various governmental subsidies for the fossil fuel industry. Given that, a subsidy for EVs is only fair.

Then you equate gasoline cars' air pollution with the enormous cost of upgrading our electrical infrastructure?

So far the grid seems to be holding up fine. I haven't studied this question, but I'm sure that at some level of EV adoption, additional investment in the grid will be required.

Spoken like a true Californian.

California has a population of 40 million, so I'm sure its viewpoint diversity is as broad as the country as a whole.

Has anybody considered where our electric comes from? How much of it now comes from fossil fuel and at what cost in air pollution?

Of course that has been looked at. In the states with the dirtiest power generation, an EV causes roughly as much pollution as a high mpg gas car (e.g. 40 mpg). The advantage is that shifting the pollution from mobile sources (cars) to fixed sources (power plants) makes it more economical to clean up the sources. In states like California with fairly clean power generation, an EV already reduces pollution compared to any gas car available.

If we have to increase our capacity two or three fold what are we supposed to build?

Personally, I'd be happy to build more advanced nuclear power. But the free market will come up with an optimal production mix if we ensure it gets the correct price signals.

Cheers, Wayne

 

[Besoeker]

Since I don't drive while I sleep, it's fine that the car is out of commission overnight.
Cheers, Wayne

How long does your EV take to charge.
Range - there are some optimistic claims. When Elon Musk revealed his Tesla Roadster I think a range of up to* 240 miles or thereabouts was claimed. This far exceeded anything else available at the time. The body was based on a Lotus Elise so we know something the drag coefficient and the power required to overcome that. They are both sports cars but if you drove the Roadster at anything close to its performance capability you would get a fraction of the claimed range. At a constant with no stops and 60 mph on a flat, level road with no stopping or starting you might get close.

Then there is the price - it was launched at $98,000. Not all are like that of course but on those I've checked they are all several thousand pounds (£) more than than the gasoline versions of the same model. Some nearly double.

That said, I do think there is a niche market for EVs (beyond the Milk Float era of yesteryear....)
But there are issues to be ironed out before they become mainstream. Not least of which is the electrical infrastructure. Generation, transmission, distribution......

 

[wwhitney]

How long does your EV take to charge.

A 60 kWh 200 mile EV with a 7.2 kW onboard charger? About 9 hours from empty, using a 240V / 30 amp continuous circuit. Most charge cycles won't drain the battery to empty, though.

At a constant [speed] with no stops and 60 mph on a flat, level road with no stopping or starting you might get close.

No, under those conditions you should get the advertised range or better. It's when you go 75-80 mph that you don't get the advertised range. Gas cars suffer a similar range reduction, it's just harder to notice when the range is 400 or 500 miles.

Cheers, Wayne

 

[Besoeker]

A 60 kWh 200 mile EV with a 7.2 kW onboard charger? About 9 hours from empty, using a 240V / 30 amp continuous circuit. Most charge cycles won't drain the battery to empty, though.

For most EVs 60 kWh is fairly big.

No, under those conditions you should get the advertised range or better.

I came up with that figure by working back from the Lotus Elise data and the battery fitted to the original roadster.

At's when you go 75-80 mph that you don't get the advertised range. Gas cars suffer a similar range reduction, it's just harder to notice when the range is 400 or 500 miles.
Cheers, Wayne

Yes. Aerodynamic drag is about proportional to the cube of the speed so naturally fuel consumption rate increases with speed. But isn't just speed that is a factor. Driving technique and traffic conditions also have a big influence. Driving on the I-285 round Atlanta during rush hour is hardly conducive to getting optimum fuel/energy consumption.

 

[Ingenieur]

drag F ~ 1/2 p A Cd v^2
power required ~ v^3 from P = F DOT v

it is F that accelerates, or overcomes drag/friction at constant v, the vehicle (thrust derived from torque)
fuel is ~ torque

 

[wwhitney]

For most EVs 60 kWh is fairly big.

That was true a couple years ago, but it is the new benchmark size. Currently available in the Chevy Bolt EV, next year expected in the Nissan LEAF, and of course most Teslas are 60 kWh or larger.

I came up with that figure by working back from the Lotus Elise data and the battery fitted to the original roadster.

OK, so that's 10 years out of date. If you haven't looked at EVs since then, take another look now.

Cheers, Wayne

 

[wwhitney]

drag F ~ 1/2 p A Cd v^2
power required ~ v^3 from P = F DOT v

Agreed, but energy / distance ~ v², which is what matters for range discussions.

Cheers, Wayne

 

[Besoeker]

OK, so that's 10 years out of date.

That doesn't validate an overly optimistic claim. Misleading even.

If you haven't looked at EVs since then, take another look now.

Cheers, Wayne

I have. Independent motoring reviews seem to all question the claimed range.
Like I said, it greatly depends on driving technique and traffic conditions. We don't live in an ideal world.

 

[Ingenieur]

Agreed, but energy / distance ~ v², which is what matters for range discussions.

Cheers, Wayne

it is still v square, not cubed
and it is specific fuel consumption/torque required for propulsion that matters
net eff


work (or energy depending on context) = F d = m a d
d = v t and 1/2 v = a t or a = 1/2 v/t
substituting
work = m 1/2 v/t v t = 1/2 m v^2
2 work / m = v^2, not work/d, that equals Force

that aside, eff has as much to do with driving style, terrain, etc

this is a 500 hp/515 lb ft, 4300 lb loaded car with ac on

 

[wwhitney]

I have. Independent motoring reviews seem to all question the claimed range.
Like I said, it greatly depends on driving technique and traffic conditions. We don't live in an ideal world.

I agree than many people speed and drive inefficiently. They won't get the advertised range. If I don't speed and drive semi-efficiently, my experience has been that I get the advertised range.

Cheers, Wayne