Difference between AC and DC chargers

Difference between AC and DC chargers

The main component of an electric vehicle is its electric motor. Basically, an electric motor is powered by an electric battery. There are mainly two ways to charge the battery AC charging and DC charging. So, let us discuss the differences between AC and DC charging in detail.

In addition, the batteries can only store DC power. So, while charging electric vehicles, there should be a mechanism to covert the input power to favorable DC power, If the input power is AC.

AC vs DC Charging systems

AC chargers

In AC chargers, there is an inbuilt on-board charger. The input given is AC(Alternating current) power, this is converted into DC(Direct Current) power before feeding the battery. This is because the battery is compatible with DC power only. This is the most common mode of charging. They are most suitable at homes and for night charging. The charging speed is in the range 22kW-43kW per km/h.

AC chargers can be divided into two:

  • Type 1 : They have a charging rate of 2.5kW to 3kW. Depending on the battery power the time required to charge varies from 1-6 hours.
  • Type 2: They have a charging rate of 7.7 kw to 22 kw. Mainly used to charge batteries with higher power rates.

Advantages

  • Cost effective
  • They are available easily
  • Installation is simple
  • Charges at a continuous rate

Disadvantages

  • They are slow in charging
  • Limited power. Since the AC power depends on the capacity of on-board charger

DC chargers

In DC chargers, DC power is given directly to the battery bypassing the on-board charger. Here the DC charger itself has a converter, that converts the AC supply to DC current before giving it to the battery. The charging speed is in the range 50-100kW per km/h. To be more precise, Dc chargers can supply the range of 100 km or more per hour of charging.

Mostly used in highways and charging stations. DC fast charging is essential for high mileage, high fleet and heavy vehicles. The charging curve is a degrading curve. In other words, the initial fast rate at which the battery accepts power decreases as it approaches its total capacity.

The charging curves of AC and DC chargers is given below:

Advantages

  • Charging speed is high
  • Ability to charge more drivers in a day

Disadvantages

  • They are expensive
  • Complex components and needs large space
  • Needs large power supply

DC chargers also accompany renewable sources of energy.

Image credits : gcepsolar.com

Indian Standard for DC charging

The IS-17017-Part-25, which is specifically for providing low DC power of less than 7kW for light EVs, was just finalised by the BIS (Bureau of Indian Standards). Communications will follow the IS-15118 series when the Combined Charging System (CCS) standard is implemented, which can support both AC and DC charging.

Difference between AC and DC chargers – Summarised

ParameterAC ChargerDC Charge
Charging Current Provides AC Current to On-board ChargerProvides DC current directly to batteries
CostRelatively CheaperHigher Costs
Charging SpeedUsually limited by capacity of onboard chargers. High Charging Speed, depends on DC Charger Capacity & Battery Voltage
ApplicationsUsually used at Home or destination chargers (overnight)Usually used at midways, conventional fuel pumps & other fast charging locations.

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