As electric vehicles increase in popularity in Australia, more homeowners are installing EV chargers. AC chargers have been the go-to EV charger for years, but as DC chargers become more accessible, are AC chargers still the best option?
We expect that with the onset of DC chargers from brand disruptors like Sigenergy, AC chargers may soon become redundant. While AC chargers remain significantly cheaper than DC chargers, the charging speed and efficiency are incomparable, plus some DC chargers are compatible with technologies like V2X and V2G.
Read more: What is V2X? Vehicle-to-everything technology
AC chargers are also limited in charging capacity - if you own one, you may have noticed that your 22kW AC charger charges at a much lower rated capacity. We’ll explain why below.
Keep reading to discover the pros and cons of AC and DC chargers for EVs.
Why DC chargers deliver faster charging
DC chargers are faster than AC chargers because they bypass the onboard charger in the vehicle and supply electricity directly to the battery as direct current (DC).
Electric vehicle batteries store energy in DC, but when charging with an AC charger, the alternating current (AC) must first pass through the car’s onboard converter to be transformed into DC. This onboard converter, while essential, has a limited capacity that dictates the maximum rate at which the battery can be charged using AC power.
In contrast, a DC charger performs this conversion externally, within the charging station itself, and delivers electricity directly in the form the battery requires.
DC chargers are equipped with more powerful conversion systems than the onboard converters in most EVs, enabling them to process and transfer larger amounts of energy much more quickly. This direct approach eliminates the bottleneck of the onboard converter and allows for significantly faster charging times.
Additionally, DC chargers often operate at higher power levels, further increasing the speed at which energy can be delivered to the battery.
Why AC chargers have speed limitations
AC chargers are limited in speed for three reasons:
- Onboard converter limitations
- Energy distributor restrictions
- Output is dependent on single or three-phase power
The conversion from AC to DC causes a bottleneck when charging your EV, resulting in a slower charging time. In addition, the onboard charger has a maximum power capacity which restricts how quickly it can process and supply energy to the battery.
As a result, the charging rate is capped by the capacity of the onboard charger, regardless of how much power the AC charging station can provide. This inherent limitation means that even if an AC charger offers high power output, the vehicle’s onboard system might only be able to handle a fraction of it for true charging speed.
Most EVs support AC charging at 11kW, though some high-end luxury brands, like Porsche, may allow higher rates. On the other hand, certain models, such as BYD, are limited to 7kW. Even if you install a 22kW three-phase AC charger, your EV will still be capped at its onboard charging limit - typically 11kW for three-phase and around 7kW for single-phase.
Additionally, electricity retailers can impose further restrictions. For example, in Queensland, dynamically controlled charging could reduce your rate to as little as 1.5kW. Electricity retailers are permitted to do this if the grid is under a lot of pressure or unstable. Unfortunately, you have no control over this.
22kW AC charger charging a Tesla Model Y on a three-phase site.
DC chargers don't have these problems
Now that you know why AC chargers are limited and why you can’t charge at their full capacity, we’ll discuss why DC chargers don’t have these problems.
As we mentioned earlier, DC chargers bypass the onboard AC charging in an EV, allowing the EV to accept the full charge. If reaching full charge as fast as possible is important to you, then a DC charger is the best solution.
One of the fastest EV chargers available on the market at the moment is the Sigenergy DC EV charger. Sigenergy is relatively new to Australia, but its tech is shaping up to be major competition against the mainstays, like Tesla and SolarEdge, and is seriously shaking up the industry. Sigenergy manufactures modular home energy systems, including a hybrid inverter, home batteries, and a bidirectional-ready DC EV charger.
Sigenergy DC EV Charger installed by Springers Solar
The Sigenergy DC EV charger module is available in two configurations:
- 12.5kW, or
- 25kW
As DC chargers don’t encounter charging limitation issues, that means you could charge your EV at its rated capacity of 25kW - one of the fastest EV chargers available in Australia.
Read more: A guide to charging your EV with solar energy
DC chargers are still significantly more expensive than AC chargers, so this is something to keep in mind when deciding between AC or DC charging for your EV. However, considering that the Sigenergy DC EV charger is bidirectional ready, it is still a worthwhile investment to future-proof your property for V2X technology.
While 22kW AC chargers can provide a steady charge, their speed is restricted by the car’s onboard charger, making them more suitable for routine or overnight charging. On the other hand, 25kW DC chargers excel in situations where faster charging is needed, making them ideal for road trips, quick top-ups, or to take advantage of low time-of-use tariffs. Understanding these differences helps EV owners choose the right charging option based on their needs.
Springers Solar | Queensland's Most Experienced Solar & EV Charger Installer
Springers Solar provides quality components with proven performance, backed by industry-leading warranties, and dedicated after-sales support. Thousands of satisfied customers over more than 23 years of operation make Springers Solar one of the most established and experienced solar companies in Australia.
Springers Solar has received multiple awards for design and installation and is a certified/preferred installer for a large range of solar panel, inverter, and solar battery manufacturers, including Tesla, Sigenergy, and SolarEdge.
Our dedicated in-house team of electrical engineers, project managers, solar PV designers, solar installers and electricians work closely with you before, during, and long after your project is completed. Springers Solar offers an industry-leading 10-year workmanship warranty which is a testament to our qualified staff and offers you outstanding value and peace of mind.
Read more about us here.
We supply and install EV chargers for homes and businesses in the South East QLD region.
Contact us about anything related to our services using the form below.
We'll get back to you as soon as possible.
Faster EV Charging: 22kW AC vs 25kW DC Chargers Explained