EV basics
AC charging suits the hours a car spends parked at home or work. DC fast charging suits shorter stops when drivers need to get back on the road. The main difference is where electricity is converted, and that affects charging speed, equipment cost and the power a site needs.
The grid supplies alternating current, or AC. An EV battery charges using direct current, or DC, so the electricity must be converted before it reaches the battery. With AC charging, the car handles that conversion. With DC charging, the charging equipment does it outside the car.
Kilowatt-hours (kWh) measure energy: how much a battery can hold or how much you add during a session. Kilowatts (kW) measure power: how quickly that energy is delivered. Think of kWh as litres of fuel and kW as the rate at which the pump fills the tank.
To estimate charging time, divide the energy needed in kWh by the average charging power in kW. Use average power, not the charger’s maximum rating, because charging power changes throughout the session. Allow extra time for losses and other limits.
An AC charging point supplies electricity to the vehicle’s onboard charger, which converts it to DC. The capacity of that onboard charger limits how much AC power the car can accept.
Common AC charging levels are around 7–22 kW, but the vehicle and the site must both support the selected power. Connecting a car limited to 7 kW AC to a 22 kW charging point will not make it charge at 22 kW.
A substantial top-up generally takes several hours. AC equipment is usually smaller and less expensive to buy and install than DC equipment, making it a practical choice for homes, condominiums and workplaces. The building’s electrical capacity still needs to be checked.
A DC fast charger contains its own power-conversion equipment. It supplies DC to the battery through the vehicle’s charging controls, bypassing the onboard AC charger.
Larger external equipment allows much higher power. Public DC chargers commonly range from around 50–350 kW, with lower- and higher-power systems also available. Depending on the vehicle, starting charge level and conditions, reaching 80% can take roughly 20–60 minutes. This is a guide, not a fixed time for every car or session.
DC equipment costs more and needs a larger electricity supply, sometimes with a dedicated transformer. It is generally used at public stations, commercial sites and fleet facilities.
| Feature | AC charging | DC fast charging |
|---|---|---|
| Conversion to DC | Inside the car | Inside the charging equipment |
| Common power range | Around 7–22 kW | Around 50–350 kW |
| Charging time | Usually several hours | Often around 20–60 minutes to 80% |
| Common connector in Thailand | Type 2 | CCS2 |
| Electricity supply | Building supply with sufficient spare capacity | Larger supply; a dedicated transformer may be needed |
| Best fit | Home, work and other long stays | Journeys, short stops and busy public stations |
Power ranges and charging times are indicative. The vehicle, equipment, starting charge level and site conditions determine actual performance.
Type 2 is widely used for AC charging in Thailand. CCS2, short for Combined Charging System 2, is widely used for DC fast charging.
A CCS2 vehicle inlet combines the Type 2 connection with two additional DC contacts below it. A compatible car can therefore use the same inlet for AC and DC charging. Connector support varies by model, and some vehicles accept AC charging only, so check the vehicle’s specifications before choosing a charger.
Consider a car with a usable battery capacity of 60 kWh. Charging from 20% to 80% adds about 36 kWh.
| Charging example | Approximate time |
|---|---|
| AC charging at a steady 7 kW | 5 hours 10 minutes before losses |
| DC charging averaging 70 kW into the battery | 31 minutes |
These are simple calculations, not promised session times. AC conversion losses, battery conditioning and changes in charging power can make the actual wait longer. The DC example assumes 70 kW is the average power reaching the battery over the session, not the charger’s nameplate rating.
The charger’s rating is its maximum output. The power a car receives depends on several factors:
Charger capability. Output is limited by the charger’s power, voltage and current range.
Vehicle capability. The car sets its own charging limit. It cannot accept more power simply because a larger charger is available.
Battery charge level. Power usually falls as the battery approaches full.
Power sharing. When two vehicles use a charger, or several chargers share a site’s capacity, less power may be available to each car.
Temperature. A battery that is too hot or too cold may charge more slowly. Battery cooling or heating can also use energy during the session.
The car’s battery management system reduces charging power as the battery fills to keep charging within its operating limits. The slowdown is often noticeable around 80%, although the exact point varies by model.
The final 20% can take a disproportionate amount of time. On a journey, stopping around 80% is often more practical if that gives you enough range for the next leg. Charge further when you need the range, and follow the manufacturer’s guidance for your battery.
A larger charger helps when the car can use the extra power. If a car accepts no more than 100 kW DC, a 240 kW charger will not push it beyond that limit. Actual speed also depends on voltage, current and the car’s charging curve.
Higher-power equipment can still benefit a station by serving faster-charging vehicles or providing more shared power when two cars charge together. Charger selection should reflect the vehicles and demand expected at the site.
Vehicles that support DC fast charging manage the session through their battery control systems. The long-term effect on battery health varies with battery chemistry, temperature and charging habits. There is no single wear rate that applies to every EV.
AC charging is a practical everyday option where it is available; DC charging is useful when time matters. Follow the manufacturer’s advice on routine charge limits and fast charging, particularly in hot weather. Some battery types have different recommendations for charging to 100%.
Plan to arrive with enough reserve. Charging is often faster at a lower battery level, but do not risk running out to save a few minutes.
Charge for the next leg. Around 80% is often enough, but route, weather and the next available station matter.
Check the app. Confirm the connector, charger power and reported availability before travelling to a station.
Free the bay when finished. Moving your car promptly helps the next driver charge.
Start with how long drivers stay. AC charging works well where cars are parked for hours. DC fast charging is more suitable where drivers want a useful top-up during a shorter visit, such as a fuel stop, meal or shopping trip.
A 20–45 minute visit can make DC charging worth considering, but dwell time alone does not determine the right power. Expected demand, the vehicles using the site and the available electricity supply all matter. At Evergreen Capital, we assess these together before recommending a station configuration.
Further reading: PEA VOLTA — EV Charger คืออะไร? มีกี่ประเภท และควรเลือกแบบไหนดีในปี 2026 · PEA VOLTA — หัวชาร์จรถไฟฟ้า มีกี่แบบ? รู้จักประเภทหัวชาร์จ EV · U.S. Department of Transportation — Charger Types and Speeds · Australian Government — Electric vehicle charging equipment
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