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JLeslie's avatar

What appliance would be the equivalent to the electricity needed to charge a Tesla?

Asked by JLeslie (65417points) June 24th, 2011

“Tesla” is now taking orders for their new sedan. From what I have read you can charge it using a regular electrical outlet or a washing machine/refrigerator outlet. What I am wondering is does it use as much electricity as say a common refrigerator or washing machine? More specifically I am curious about the strain on the circuit breakers in the house, or even how much load this would add to the grid say many people in the neighborhood had one.

Feel free to comment on the car itself also. If you would buy an electric car or a Tesla specifically. Also, if anyone has seen the new sedan in person I am curious to hear your opinions on the comfort and style, and what car you might compare it too.

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22 Answers

Tropical_Willie's avatar

The quick charge, I believe, is 240 Volt and up to 70 Amps. Twice the voltage and almost five times the amperage of your refrigerator. That charging system can cost $2500 installed.

Dr_Lawrence's avatar

If I had the money to buy any car, I would buy an electric car only if the electricity where I live is generated with wind power or hydroelectric turbines.

If your electricity is produced by burning coal or oil, then your electric car would contribute as much or more to pollution than one powered by gasoline.

FireMadeFlesh's avatar

The Telsa website says the Model S is engineered to be recharged in 45 minutes. I’m guessing that is for the one with the smallest (160 mile) range. That may also be for three-phase power only. From a standard power point it would probably be longer. I think they suggest that it is plugged in every night so it has a full charge at the start of every day.

Personally, I wouldn’t be game to buy an electric car yet. I am planning to stick with efficient petrol or diesel in the short term, but I expect hydrogen fuel cells like in the Honda Clarity to become the smart choice in 10–15 years.

Edit: The 45 minute charge is from a 480V power supply (not sure who has those?), presumably for the 42kWh model. A 70kWh model is also available. Source.

jerv's avatar

Which battery pack, at what voltage, and how much do you care about the longevity of the battery? While the Tesla can be quick-charged if you have an appropriately burly power source, doing so too often will kill the battery, so that right there will mean that most charges will (or at least should) be “low and slow”.

Also, voltage plays a key role here as Watts equals Volts time Amps, so more volts means less amps. SO give me a little more information.

@FireMadeFlesh There are enough problems with hydrogen that I don’t see it being viable within the next century or so. Hydrogen isn’t exactly easy to package, we have practically no infrastructure for it, and the well-to-wheel efficiency of a hydrogen fuel cell vehicle is about one-third that of an EV like the Tesla Model S, and, in fact, is only about ¾ as efficient as the average gasoline powered car!
So tell me, why should I view them as much more than a curiosity when we already have a technology that is well over a century old that works better and far more efficiently?

FireMadeFlesh's avatar

@jerv All these are only problems because it is nothing like what we’ve ever done before. Infrastructure always follows demand, so as the technology advances it will become profitable to build supporting infrastructure. Packaging is a problem because people expect the motorist to fill the car. If we brought back service stations that fill your car for you, and train personnel to use delivery systems with air-tight locking mechanisms, all you would need is a thick walled fuel tank and an air compressor. Extraction of hydrogen is the biggest problem as far as I am aware, since current methods rely on cracking fossil fuels, which as we know are swiftly running out.

Hydrogen deserves to be taken seriously, because it is the most car-like zero emissions technology. Battery power is hugely inconvenient, because if you ever want to drive more than 350km in a day, you need to stop for hours to recharge (as you said, low and slow is the best for reliability). Swapping out the batteries takes a lot of manpower, and each service station would need to keep stocks of every type of battery – very inconvenient when each car has hundreds of them. Hydrogen works just like petrol, in that you can fill the car in minutes and be on your way again. All we need is an efficient extraction process, and for existing energy companies to see profits in adding hydrogen to their petrol networks.

LuckyGuy's avatar

You need to know the capacity of the battery and how fast you can deliver power to it to answer your question.
I have seen a range of numbers for the battery capacity. It seems 56kWh (kilowatt hours) is pretty close. Let’s assume that. You can change the number if you like. Also assume the charger is 100% efficient. It’s not. You can multiply the charging times by 20% to be more realistic.

Your house has 220 Volt service and most likely a 200 Amp main breaker. Therefore the most that you can deliver, if everything in the house is turned off is: V x Amps= Watt so 220×200 = 44kW. That means the theoretical limit of your entire home will charge an empty Tesla battery in 56kWh/44kw= 1.3 hrs. (Again assuming the charger is 100% efficient.)

Now let’s look at the other extreme. Say you want to charge it from a typical 110Volt outlet with 15 amp breakers. That is 110 V x15Amp=1650 Watts or 1.65kW. So it will take 56kWh / 1.65kW = 33.9 hours to fully charge it from a 110 volt outlet.

Let’s say you use the same plug that is on your electric dryer. 220 V 30 Amp. That is 220V x 30 Amp = 6600 Watts So it will take 8.4 hours. To fully charge it.

Since no charging system can be 100% efficient you should add 20% to the times to make up for the various losses.
So, to fully charge a Tesla 56 KWh battery from completely empty, depending upon the power source it will take:
Full house 200Amp service —- 1.5 hours
Typical clothes dryer service —10.2 hours
Typical 110 V outlet, 15 Amp — 40.7 hours

Most likely you won’t be fully discharging the battery every time. To extend battery life there are limits to how low and how high you can go. The numbers above are for a fully discharged battery – like filling your gas tank from truly empty.
The laws of physics are hard to beat.

jerv's avatar

@FireMadeFlesh “All we need is an efficient extraction process, and for existing energy companies to see profits in adding hydrogen to their petrol networks.”

No such thing (which is the problem) and not worth the transition expense in the foreseeable future.

@worriedguy That is why 220V is strongly recommended, and some EVs don’t allow a 110 option. Of course, since most people only drive 60 miles a day, it’s not as big an issue as some people think.

jerv's avatar

Okay, just had a talk with a few guys from SEVA. It really varies. The Tesla Roadster can charge (safely) in four hours at 70 amps on a 240V line, and that will last the average driver about four days. Do the math and you’ll see that a one hour top-up power day will suffice for those that have a charging station with that sort of amperage.

Of course, it’s moot since the Model S can swap battery packs in about the time it takes to refill a gas tank, and the infrastructure for that is a hell of a lot cheaper and simpler than for hydrogen. As for having to stock hundreds of types of batteries, how many type of gasoline are there? It would be simple to standardize car batteries the same way that we have with others; my camera uses the same battery as my flashlight, my wireless mouse, my beard trimmer, and my TV remote.

JLeslie's avatar

I read that “overcharging” is not a concern for the Tesla battery.

jerv's avatar

Overcharging is and isn’t a concern. Any reasonably intelligent charger will work with the battery and automatically cut off when the battery is full. However, a “bad boy” charger doesn’t care I’d the battery is full, or even if it’s on fire.

LuckyGuy's avatar

Their numbers are pretty close to mine. Using my assumptions, for a 70 Amp service, it should take 4.3 hours. Of course the numbers match. It’s physics.

70 Amps, 220 V service is pretty large. My dryer is 30 amps. I have 50 amp service to my barn for my welder. 70 amps would require a significant upgrade.

jerv's avatar

@worriedguy I believe that is part of the price of the home charging station.

Then again, a gas pump is an investment for a gas station, probably a more expensive one than upgraded electrical service, so it would make sense to have service station put in chargers and then charge, say, 20ยข/kwH to charge up. I’ve seen chargers in parking garages/lots, and on-street parking in many cities is enough of a hassle that many use such places to park while they work anyways. Hell, charging while you work may make more sense anyways as most workplaces are in places that have heftier service lines than the average house. I know my workplace does; we have arc furnaces.

FireMadeFlesh's avatar

@jerv I suppose I’m sceptical because my laptop battery lost half its charge capacity in the first six months of ownership, and family members have had laptops that won’t charge a perfectly good battery because of faults. Media articles often compare electric cars to laptops in terms of power supply, which is why I make the connection here. The mechanicals in a petrol car rarely die in the first several years if it is driven normally (no burnouts or crunching gears etc.). A hydrogen car needs a reliable fuel cell, and that’s it. I did find your efficiency figures very interesting though.

koanhead's avatar

@FireMadeFlesh I think you are confusing the hydride tank (the only known way to stably store hydrogen without outgassing) with a fuel cell.
The term “fuel cell” means two different things:
1) some racing cars store fuel in a special container called a fuel “cell” instead of a tank.
2) a device that uses catalysis to generate electricity from the action of a fuel (hydrogen or ethanol typically) upon an oxidizing agent.

The first sort of fuel cell does not work well to store hydrogen. The hydrogen molecule is very much smaller than any other known molecule- small enough that it can pass through many materials unless stored at very low temperatures or very low pressure.
The second sort of fuel cell does not store hydrogen, but reacts it to produce electricity. The hydrogen to run the fuel cell must still be stored somewhere on the vehicle.
Since fuel cells are not 100% efficient, and the production of hydrogen by electrolysis is also not 100% efficient, there are added losses to the system over a battery-powered electric car.

FireMadeFlesh's avatar

@koanhead I am very much aware of what a fuel cell is. Maybe I wasn’t clear enough in my wording, but none of what you posted is new information to me.

LuckyGuy's avatar

@FireMadeFlesh You brought up the weak link in the system: the battery’s capacity and energy density. It’s capacity is reduced with time, number of charges and temperature. We all have Lithium Ion batteries in our phones and laptops and know how that’s been working. How many of us have asked, “Is that the 2 hour, 8 hour battery, or the 4 hour 8 hour battery?” Our cell phones batteries seldom work longer than 300 charges even if we are extremely careful. The energy density is well understood to be about 1/50 to 1/80 that of gasoline. The battery as rated above weighs over 950 pounds and holds about the same energy as 2 gallons of gasoline. Granted, the total efficiency of the system (70–80%) is higher than that of an internal combustion engine (35–40%) so let’ s call it 4 gallons of gas. In winter the “inefficient” IC engine uses the waste heat to warm the passenger compartment. The battery car must use auxiliary heaters which suck power and reduce range.
The Teslas are being field tested in warm climates for a very good reason.

koanhead's avatar

response deleted

jerv's avatar

@FireMadeFlesh I take it that those batteries were abused in some manner, quite likely overheating. There is a reason that EV battery packs have their own cooling systems; something most consumer electronics packs lack. Personally, I have yet to have a pack decline that fast. My netbook lost ~15% in just over a year, but that thing was cycled fairly often as it was only about a three-hour pack. (I went for the lighter one that didn’t stick out the back or bottom so as to keep the thing square and avoid ripping the battery out by the bulge during transit.) My year-old laptop has been cycled far less often and is still >90%. There are Rav4 EVs that are still on the original pack after all these years and miles.

I don’t trust the mass media when it comes to science, especially not when they fly in the face of what I know from my years as an electrician, my experience as a hobbyist, or anything else I know I know. I may use them as a starting point for further study, but I prefer learning the science and engineering over taking someone else’s word for things.

Hydrogen needs a storage tank made from Neutronium to prevent seepage; there really is no way around the simple fact that a hydrogen tank made of normal materials is like a soup bowl made out of gauze. More importantly is the issue of how to get massive quantities of hydrogen efficiently?

Many people who are new to EVs tend to drive them like a gas-burner, and that is not wise; it leads to broken stuff, most often the battery. Ask @koanhead about that as he has more EV experience than I do.

…............................................................................................

@worriedguy Not entirely true. Warm climates take their toll on batteries in another way, not counting the effects of running A/C. There is a reason that the Nissan Leaf lists it’s range under various conditions .

But you, like many others, seem to overlook one simple fact; MOST PEOPLE DON’T DRIVE THAT MUCH!!!! I had to shout that since it seems that that point is so overlooked that the only chance I have at getting it across is to emphasize it in ever way I can, and I wish I could put it in flashing neon letters in a 72-point font. Does a family of three need a seven-seat SUV? Probably not. Do we need a car capable of doing 0–60 in under five seconds? As cool as that is, I don’t think the average person needs that, and in fact, doing so on most streets will get you a ticket. Do you need a top speed of more than 100 MPH? Not in a country where most places hand out tickets for 80 or less. Let us ignore that the Tesla Model S seats five adults and two kids, can do 0–60 in 5.6 seconds, and tops out at 120MPH :D

So, how much range does the average person need? Most figures I’ve seen place the average pretty damn low. Let’s see… 33 miles per vehicle per day, 29 miles per day, ~45 miles/day (overall average)… well, you get the idea. So with numbers like that, the only reason a 60-mile range is unacceptable is that people are too lazy to recharge/refuel. Either that or they are so used to burning five gallons a day in their low-MPG rigs that when they hear that a battery only packs the same energy as two gallons of gas, they get scared. Let us ignore the Tesla’s range that is about what I get on a ten gallon tank of gas in my gas-burning Corolla.

There are times when just looking at some numbers works, but there are other times when you have to look at more numbers to actually see the truth. Electric vehicles fall into the latter category.

LuckyGuy's avatar

@jerv I agree, most of the time people do not need to drive that much. The car would be fine for short hops where the traffic pattern is well known. But if someone has a 1 hour commute and ends up in traffic due to an accident I predict there will be a lot of dead batteries out there. Imagine driving a small car with a total gas tank capacity of 4 gallons. (The battery is actually equal to 2 gallons but I am doubling it because off the high efficiency.) This number will degrade when it gets cold and when it ages.
I have couple of motorcycles (3 and 4 gallon tanks) and a couple of cars. If I had a Tesla, my rules for driving would be similar to the rules I have now for my Kawasaki: Don’t drive it when it’s cold out and take it on short hops.
The Tesla will be fine for people who have access to two cars, live in a moderate climate, and commute a few miles every day.
Wait. This sounds like the same rules I have for riding my bicycle.

Let’s ignore the ~250 pounds of lithium needed for every battery and the cost of recycling. The market will handle those issues. (If China does not lock up the strategic reserves first.)

I don’t mean to sound totally negative. I’d love a Tesla if it cost $16,000 and it had a heater that would work in my climate. Unfortunately the price is much higher. When gasoline gets to $10 per gallon (and it will) and, if the price of electricity stays at $0.20 per kWh (not likely) and if the value of money is 4%, it will still take forever for the economics to pay for itself. It is in no way an economy car.
I do not ride my motorcycles to save money. I do it for the fun. That would be a reason to buy a Tesla.

jerv's avatar

@worriedguy You pay about twice as much for electricity as I do, and not everybody lives somewhere where heat or A/C is required. And I know quite a few EV owners (Tesla, home-brew… you name it) in the Seattle area and one in NH so I am not entirely convinced you know what they are truly capable of.

You also forgot to mention that electric cars don’t idle, so being stuck in traffic isn’t quite the issue you claim it is unless you think that climate control really is that big a drain. Or maybe it’s just that Seattle traffic moves better; I have yet to be stuck on I-5 for more than about 40 minutes.

Then there is the fact that battery technology is advancing fairly steadily, and has been for over a century when the first electric vehicles were out (back in the days when gasoline was a cleaning solvent sold at drug stores). Unlike hydrogen fuel cells, batter-powered cars can actually be commercially viable within a decade. Even better, if you do it right, you can replace the batteries with a fuel cell once that technology evolves a bit more… and it may not be a hydrogen fuel cell!

I think it will be a while before the cost of a fuel cell can compete with even a Lithium-ion battery (Honda is taking a loss on the Clarity), they still are not up to snuff in cold weather either, and their longevity ranges from barely comparable to utterly pathetic, so I don’t see fuel cells doing well for at least another 15–20 years.

Oh, and I don’t know many people who buy a two-seater sports car for everyday driving. Ever seen somebody shopping for groceries in a Ferrari? How about taking the kids to soccer practice in a 911? And that is also why the Model S is coming out.

LuckyGuy's avatar

@jerv I know electric cars don’t idle. Neither do newer gasoline engine cars with Integrated starter generator mild hybrids. The lights and accessory loads continue to draw, however. I am quite familiar with the loading required for climate control. See this report from DOE NREL . It can be similar to the road load of a midsized car moving at 35 mph, or higher if you have a small car with a good drag coefficient. Of course, the manufacturer can undersize the A/C or suggest people not use it. .
My concern is the over selling of the concept. If they admit upfront that the vehicle has some shortcomings: should be be treated as a sporty car, should be used on short trips on days when climate control is not necessary, should be charged after each use, ... (i.e. Motorcycle rules.) That is fine. When they make specialized claims of 150 mile range, 40 minutes to fully charge, etc. people will expect to see that and the backlash will be huge. One dead Tesla on the side of the road and they will have a PR disaster. Six toasted batteries because customers used fast charge too often and they will have a recall.

They should not oversell the capability or hide the shortcomings. The penalty will be huge.
Here’s an example. A couple of years ago a certain car manufacturer made a claim that their Flex fuel truck got “100 miles per gallon of gasoline” on E85 fuel. They did not say that for every gallon of gasoline, 5 gallons of ethanol was used. There were people who did the math and said “100 miles on a gallon of gas! That costs me $3. Great!” They bought the vehicle and discovered it only got 16 mpg on E85. It took 6 gallons of E85 at $15 to get that one gallon of gasoline. Sure, the company made a sale but they got a bunch of PO’d customers. The car manufacturer was not lying, but it certainly was misleading. The backlash was huge and the manufacturer is still paying for it.
I hope Tesla does not make the same mistake.

jerv's avatar

I hope so too, but given what I’ve seen over the years, I predict problems no matter what. If McDonalds can be sued for making people fat or serving hot coffee, a shoemaker can be sued because a person injures themselves tripping over their untied shoelaces, and Toyota gets myths surrounding it (yes, they had issues, but the brakes are stronger than the engine, the engine can be turned off, and there is always neutral) I am certain that it’s a no-win situation for anyone who makes or sells anything.

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