Ac versus dc charging – what is the difference – plug in americaplug in america top universities canada

For many people, it doesn’t matter. DC is faster, and that is all that they need to know. But for the curious, this is a simplified explanation of the difference between AC and DC charging. Technical details are intentionally glossed over here.

DC is the simple positive-and-negative type of electricity that you probably experimented with in 7th grade science. A key advantage is that it is easy to store in batteries. That is why portable electronics – flashlights, cell phones, laptops – use DC power; they have to store it. Plug-in vehicles are portable so they use DC batteries too (although most of them have AC motors – a complicating step we may consider another day).

AC electricity is a little more complicated because it switches back and forth, but a key advantage is that it can be transmitted economically over long distances.

That is why AC power comes in through the power lines to your home, and is what is available at power outlets. Stationary appliances that use electricity directly from an outlet – lamps, refrigerators, washing machines – use AC power.

Because the electric grid provides AC, the electricity must get converted to DC when you want to charge a portable device. Top universities for business this conversion is done by a “rectifier”. Portable electronics that recharge from wall power all have one: it is usually in a black box in the charging cord, along with some other components we will ignore. You’ll notice that the more power the device uses, the larger that box is. The key to understanding AC versus DC charging is learning where the box is, and why.

AC outlets are ubiquitous, so to make charging convenient your car should be able to plug in to them. That means every car has to be able to convert AC to DC. The conversion equipment in current plug-in cars varies; most can convert up to 3.3, 6.6 or 9.6kW of power.

For comparison a typical household outlet can continuously provide up to 1.4kW, and “high-power” 240V outlets sometimes found in garages and RV parks can provide up to 9.6kW. It is technically possible for a car to convert far more power than that, but the equipment would be bulky, heavy, expensive, and hot – and anything over 9.6kW would see infrequent use because higher-power outlets are not available.

To illustrate this point: the tesla model S offers a $1,500 option that allows the car to convert up to 19.2kW. Twice-as-fast charging is obviously an enormous benefit when you can use it, so some owners swear by it – but you can only get that much power if you use special hard-wired 240V charging equipment. Washington university in st louis tuition the west coast has a few such chargers along popular travel routes, but such equipment is hard to find, not needed for overnight charging, and still far slower than DC charging. Many owners skip this option to save money and weight.

DC charging stations have special grid hookups so they can get and convert far more power. DC stations are big, expensive and have a lot of cooling – it wouldn’t be practical to put that equipment in every car, even if there was a way to plug directly in to the grid.

At higher cost, the grid could supply even more power; but these limits are largely set to avoid harming the car batteries while charging. (many factors determine how fast batteries can charge, but currently cars that use superchargers have significantly larger batteries than cars that use chademo chargers. All else being equal, larger batteries can accept more power without harm).

An easy way to visualize the AC/DC charging differences is to consider how tesla handles charging for their model S sedan. They make large quantities of boxes they call “chargers” that include a 10kw rectifier to convert AC to DC. American college kandy every car they build gets one for AC charging, and so can handle all the power than any outlet provides. Plugged in to the right outlet, this can charge a car at up to 24 mile of range per hour.

Did this help you understand the difference between AC and DC charging, and why both types are important? Did you see any mistakes? (not counting omitted details as they were left out on purpose to keep it simple – unless they are salient). Do you have additional or different points to help understand the difference? Are there related topics that you would like to know more about? Please let us know.

I am an EE and I have been working and experimenting with AC and DC for over 50 years. The volt motor can run with AC, but the only method that exists to store alternating current is in a flywheel generator. So for now, all electrical energy storage for consumer use is in a DC format, using mostly a chemical battery (there are electrostatic batteries but are not efficient).

As for DC charging, the most common method is to supply a higher voltage than what the cell chemistry uses. In a lead-acid automobile battery which has six 2.2 volt cells in series, the alternator applies more than 2.4 volts per cell, or about 14.4 volts for the entire battery (you can see this by measuring across the battery with a DC voltmeter while the engine is running). Lithium-ion cell chargers (such as USB types)used in mobile devices, such as smartphones and tablets, apply up to 4.2 volts for the cell. The cell voltage average is 3.7 but actually operates between 3.4 volts (discharged) and 4.0 volts (fully charged.

There is another item that hardly anyone notices, but the actual charging method in use is ADC (alternating direct current). True AC alternates between a positive and a negative current flow (like a pendulum) and crosses zero volts twice per cycle or hertz (home current cycles sixty times per second or at 60 hz), while direct current only flows in one direction and is constant. ADC is a current flow that alternates between a positive maximum and zero volts.

Why is it better? Because it allows the ions in a chemical battery to move when the voltage is at the maximum, then allows them to organize against the electrodes when the voltage is zero. This is like trying to get people to move into a conference room. You apply some pressure to move them, but release the pressure so they can move more freely and get in line across the rows. Top universities europe A constant pressure will move them but they will not fit well, create some resistance and friction, and cause some to trip and fall on the floor. Ions are atoms with missing electrons and are just as hard to move!

Proof? Get a multimeter that can measure both AC and DC, then (using the plug-in USB charger as an example) measure the AC voltage first on a 20 VAC scale. You will see up to 7 VAC! (remember that USB is based on 5 VDC) now if you could use calculus for a half wave signal and use 7 as a peak voltage, the average or RMS (root-mean-square) is about 4.1 volts, which is the average DC measured at the same time, and about the correct DC voltage that will charge a lithium-ion cell.