Electric Vehicles: The Difference Between AC and DC Charging

[Bs_lead]When it comes to charging your EV you’ve got a few options. One of those being whether to stick with AC charging or to dabble with DC.[/bs_lead]

Most electric vehicles can benefit from AC and DC charging, but what does that mean for you and your brand-new Tesla? And which option should you go for? In this article we look at your EV charging options, so you can get the most out of your EV.

→Related article: Top Selling Electric Cars in New Zealand

AC/DC: What is it?

AC/DC is more than just a group of aging Aussie rockers, it refers to the two main types of power.

Electricity comes in two forms—alternating current (AC) and direct current (DC). To summarise that briefly, with AC, the flow of charge exhibits a periodic change in direction. With DC, the current simply moves in a single linear direction. But unless you’re a high school science student, that’s not very important.

What you do need to know is that AC is the standard type of current that comes out of the power socket in your home. That’s because while DC is more consistent in voltage output, AC can travel further and is much easier to send down the power lines.

Although, many electronics contain an onboard rectifier that converts AC to DC. Particularly anything that stores power in a battery, such as a smartphone and, of course, an electric vehicle.

What does that mean for my EV?

What this means is that when you plug your EV in at home, you’ll be charging it via AC charging. However, an onboard rectifier is actually taking this, converting it to DC, and storing that power in the battery.

While this is standard, it’s not the most efficient way of charging your EV. Which is where DC charging comes in.

AC and DC charging

As mentioned above, the power that comes down the lines is AC. It’s then converted into DC to be stored in your EV’s battery. However, AC and DC charging refers to where this DC conversion happens.

With AC charging, your vehicle’s onboard rectifier converts AC to DC and stores it. With DC charging, the charger itself converts the current before it enters the vehicle. In doing so it can bypass the onboard conversion and charge the battery directly. And because it skips this step, it’s much, much faster. It also allows DC chargers to be much bigger and beefier (up to 300w vs the 7.2w of most home chargers).

In fact, the fastest DC chargers available can deliver up to 400km of range in just 15 minutes! Compare that to your standard home charging set-up, which delivers about 1km-10km per 15 minutes.

AC charging vs DC charging: the pros and cons

When we are talking about AC vs DC charging, we are really talking about at-home charging vs fast charging at a public charging station. As you simply can’t get yourself a DC set-up at home, and most public fast chargers are DC chargers.

Although it is important to note that some public charging stations offer a mix of AC and DC chargers. It’s also worth noting that both AC and DC chargers come in different wattages, which impacts their speeds (see below). So not all AC chargers and not all DC chargers are created equal.

Speed

DC charging is, by far, faster than AC charging. While speeds vary depending on factors such as the make and model of your vehicle, as well as the age, a rough estimate for the expected speeds can be seen below.

15 minutes of charging provides:

• 2km of range on a standard 2kw at-home charger (AC)
• 10km of range on a standard 7kw at-home charger (AC)
• 33km of range on a 25w fast charger (DC)
• 66km of range on a 50w fast charger (DC)
• 400km of range on a 300w fast charger (DC)

Importantly, depending on the age and model of your EV, you may not be able to use chargers above a certain wattage, so be sure to check your vehicle manual.

Availability

DC charging may provide the best speeds available, but it’s limited in availability. Currently, you can only get it at select public charging stations. And even then, not all chargers are made equal.

For example, a 300w DC charging station may offer 400km of charge in just 15 minutes, but nearly all fast chargers are currently 25w or 50w, which offers about 33km-66km of range in 15 minutes of charging.

AC charging can be done at home via a simple 3-pin plug (although this is by far the slowest option) or with the installation of a dedicated EV charging box. Simply park up after work, plug it in, and leave it for a few hours. Or even overnight!

→Related article: Electric Kiwi Helping Charge the EV Drive

Cost

Charging at home is much cheaper than charging on the go. Public chargers typically charge you for the benefit, as much as about $10 per 100km of charge. Compare this to at-home charging which, on the average electricity plan, works out to somewhere around $3 per 100KM.

And that’s before you account for EV power plans, which offer discounted or even free power hours to make charging an EV even cheaper!

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Battery degradation

While DC charging is handy should you be running low when out and about, or when you need to charge mid-road trip, it’s not suitable for your daily charge. This is because it does affect the car’s battery to a greater extent, and can lead to it degrading faster. Meaning you’ll likely notice your EVs range taking a knock earlier in its lifespan.

AC charge on the other hand, affects the battery to a much lesser extent.

Compare electricity providers with Canstar Blue

If you have an Electric vehicle, or are thinking about getting one, the right power plan is paramount. But finding the right provider can be a real challenge. Less than half of Kiwis believe they are getting a good deal on their power, yet only 12% of us have actually changed our electricity provider in the last 12-months.

If you are looking to change electricity providers, or are unsure if you are getting the best deal, Canstar Blue can help. We rate NZ power companies for customer satisfaction and value for money, see the table below for some of the results, or you can click on the button below for the full results of our survey.

Canstar Blue’s latest review of NZ power companies compares them on customer satisfaction. The table below is an abridged version of our full results, available here.

Compare electricity providers for free with Canstar Blue!

About the author of this page

This report was written by Canstar Content Producer, Andrew Broadley. Andrew is an experienced writer with a wide range of industry experience. Starting out, he cut his teeth working as a writer for print and online magazines, and he has worked in both journalism and editorial roles. His content has covered lifestyle and culture, marketing and, more recently, finance for Canstar.