Charging 101

1. Charging operation principle and mode

The charging principle of EV chargers mainly assists in transferring power from the grid to the vehicle's battery system.

According to different uses and forms, it is divided into the following main subjects for introduction:

1.1 Charging operation principle

The grid supplies alternating current (AC), which is charged into the car through charging piles. Then, the AC is converted into direct current (DC) through the on board charger (OBC) installed in the EV, and then input into the battery of the EV.

However, since the OBC is installed in the car and is limited by size and weight, the charging power is not high, which results in a slower charging speed and takes a longer time. It is used in slow-speed and medium-speed charging.

AC chargers require a long charging time, typically taking an average of 3 to 8 hours to fully charge. Therefore, they are usually used in residential areas, commercial buildings, restaurants, department stores, hypermarkets, and even overnight hotels, B&Bs, etc., which are very suitable for setting up AC chargers.

In addition to personal use, commercial use not only enhances customer shopping and accommodation experiences but also attracts EV owners to stop and spend. This not only makes your business stand out but also demonstrates the company's commitment to sustainable development.

【Advantages of AC charger】Lower cost, Easy installation, Battery life protection, High versatility, High energy efficiency.

The grid supplies AC, after AC/DC conversion at the charging station, the DC is input into the EV battery. In this method, appropriate power electronic equipment has been installed in the DC charger.

Since there is no need for conversion through OBC, the DC charger design has no size restrictions. Multiple sets of charging modules can be designed to increase the charging power, so the charging speed is faster. It is used in high-speed charging.

DC chargers greatly shorten the charging time of EVs. It takes an average of 30 minutes to 1 hour to fully charge (depending on the actual power of the EV battery and charger), so it is very suitable for EV owners who want to take a short break. It can be used in convenience stores, gas stations, near interchanges, highway rest stops, factories, commercial buildings, restaurants, shopping malls, and even commercial fleets such as taxis and buses.

Because DC chargers involve higher voltages and currents, the design will be more complicated, and special high-power circuits must be installed, so the construction cost is higher. They are often used for commercial purposes to help you alleviate customers' range anxiety and provide faster and more convenient service.

【Advantages of DC charger】Fast charging speed, Supports large-capacity batteries, Suitable for long-distance travel, Improves the utilization rate of chargers, Applies more advanced technologies.

The power unit for calculating electrical capacity is "Watt" (W), and the capacity of "1,000 W" can be abbreviated as "1kW", and so on. Common units include 1MW (1000 kW), GW (1000 MW).

So what does kWh mean? How far can my EV travel after it is fully charged?

A widely used representation of the kilowatt-hour is "1 kW⋅h", it is commonly used in billing for delivered energy to consumers by electric utility companies.

It is an energy unit that represents the power consumed by an electrical appliance whose power consumption is 1kW and is used continuously for 1 hour (h).

The calculation formula is as follows:

1 kW⋅h = 1 (kW) x 1 (h)

For example,

A. A water cooler that consumes 1 kW of electricity and operates for 1 hr, the power it uses is calculated to be 1 kWh.

B. A desktop computer with a power consumption of 500 W, used for 2 hours, the power it uses is also calculated to be 1 kWh.

The unit of EV battery capacity is kilowatt-hour (kWh), which refers to the amount of electricity stored in the battery.

The current common EV battery capacity is about 60-80kWh, with the development of technology, different brands also have cars with better performance. For example, the high-end model of Audi Q8 e-tron model has a battery capacity of 114 kWh.

The calculation formula is as follows:

Charging time (hours) = battery capacity (kWh) / charging power (kW)

Assume that there is an EV with a battery capacity of 90kWh and it is charged using a 180kW EV charger.

Without considering other factors, how long will it take to fully charge?

90 (kWh) / 180 (kW) = 0.5 hours

It takes about half an hour.

How far an EV can travel is mainly calculated by calculating its energy efficiency, also called energy consumption. This requires an energy consumption test to know the actual number.

The calculation method is "How many kilometers can an EV consume 1kWh of electricity? " in units such as kilometer per kilowatt-hour (km/kWh).

Depending on each EV model and driving habits, the energy consumption of EVs varies. On average, each kilowatt-hour of electricity can travel about 4 to 6 kilometers.

Suppose you have an EV, and you use a 180kW charger to charge your car for 0.5 hours.

180 kW * 0.5 h = 90 kWh

You will use 90 kWh of electricity to charge your car.

90 kWh * 5 km/kWh = 450 km

Your EV can travel approximately 450 kilometers.

When many car owners consider purchasing an EV, they have doubts and worries about the range, which is the so-called "range anxiety." The calculation unit of cruising range is kilometers (Km).

Under different testing environments, conditions and methods, even if it is the same model, there will also be a certain gap in the mileage data tested.

At present, the common international testing standards are mainly the following three:

Standards established by the European Union in the 1970s, tested by turning off all electronic devices on the car and using large fans as wind resistance. The process will simulate urban and non-urban driving conditions respectively, and finally give the average cruising range.

The conditions of the NEDC test simulation are designed without considering external factors, which are very different from actual road driving conditions.

Therefore, most of the NEDC test result data are very good, if converted to actual driving situations, there will be a gap between the actual data and test result data.

The standard improved by the European Union in 2017, like NEDC, is simulated and tested in a laboratory environment.

WLTP does not consider external factors such as weather and human factors. Still, the standard process is more complex and rigorous, and many variables are added (parameters are adjusted according to vehicle weight, horsepower, etc.).

Therefore, compared to NEDC, WLTP is more in line with the actual driving conditions of EV owners' situation.

Test standards developed for the EPA and specific to the US market.

During the test, the vehicle needs to be fully charged and turned off for 24 hours before testing. It mainly simulates the real conditions in urban areas and highway sections and will frequently accelerate and decelerate.

Since the test will consider environmental factors such as temperature, weight, wind resistance, and human factors, and the score will be directly deducted by 30%, it is regarded as the most stringent test standard. The result data will not look good, but the test results are the closest realistic driving situations.

The test process is a bit like NEDC, which comprehensively simulates the road condition analysis of vehicles on different road conditions such as Chinese urban roads and suburban highways. The test results reflect the actual driving conditions of EVs in China.

Evaluation conditions for purchasing EVs, in addition to evaluating the energy expenses of fuel vehicles and EVs, the convenience of charging is the focus of car owners.

Compared to waiting in line at public charging stations, installing a private charger in your own parking space offers several advantages. You won't waste time queuing and will have the flexibility to charge your car whenever convenient. You can easily fully charge your car and go out.

Depending on relevant preferential policies of local government, you can also enjoy dedicated electricity prices, and saving money.

There are thousands of environments for installing charging piles, and there will be different situations. Therefore, it is the first prerequisite to understand the environment in which the charging device will be installed. It is also necessary for qualified professionals to assist in evaluation and installation, and to comply with local laws and regulations.

A single-family private house with an independent garage is the simplest. That is, you can decide to install charging piles without the consent of others. At the same time, you need to confirm that the power in the home is sufficient. The rest is to solve the wiring.

Regardless of whether it is a new project or an existing old community building, you can apply for the installation of home charging piles. The application procedures for the two are the same, the only difference is "the name of the applicant". The new community may be under construction, so it is advisable to apply in the name of the building license holder, while for the old community, apply in the name of the management committee.

Source：Taipower Monthly Issue 725 (visit the website)

A. Evaluated based on daily driving mileage

【Short mileage】

  If your average mileage is about 30-50 kilometers, a home AC charger is sufficient.

【Frequent long-distance commuting/business trips/travel】

  Depending on the distance, budget, etc., the setting of a DC fast charger can be considered.

  It is also recommended that you plan a driving route with sufficient public DC chargers in advance to help you have a smooth journey.

【Charging at home overnight】

  A home AC charger can meet your needs.

【Frequent need for quick charging】

  If your budget is sufficient, you can consider the necessity of setting up a DC fast charger.

A. EV built-in OBC capacity

First, confirm the power limit of the EV's OBC to avoid unnecessary overhead.

For example, assuming that the OBC power upper limit of EV is 7.2kW. Purchasing higher-power AC chargers such as 11kW will not increase the charging speed, which is an unnecessary cost.

Just like the Micro USB port for mobile phone charging cannot be connected to the Lightning charging cable, different brands or new/old car models, might have different kinds of charging connectors.

The charging port also needs to be confirmed, to ensure that the charging port specifications are the same, or you have a qualified adapter to use.

Currently, common interfaces include Type 1 (SAE J1772), Type 2 (Mennekes), CHAdeMO, NACS, CCS1, CCS2, GB/T, etc., as well as the new specification ChaoJi developed in recent years.

If you are charging at home at night and can accept a longer charging time, an AC charger will be a good choice for you, and the installation price is lower.

If you are a supermarket/office operator, or you operate a travel rest stop, etc., and have fast charging needs, you can consider DC chargers. Although the installation cost is higher, the charging speed is fast, and it is suitable for short breaks or emergency charging needs.

A. Equipment costs

In terms of the cost of simply purchasing EV charger equipment, the cost of AC chargers is lower, while the cost of DC chargers is higher.

For example, assuming that the OBC power upper limit of EV is 7.2kW. Purchasing higher-power AC chargers such as 11kW will not increase the charging speed, which is an unnecessary cost.

The cost of setting up charging equipment, such as power system configuration, installation of charging equipment, hiring of professionals, etc.

The expenses that may be incurred during the use of chargers include electricity bills, maintenance fees, etc.

A. Intelligent charging management

You can monitor and control the charging process, set charging time, view charging records, etc. through the mobile App.

Choose a charger with comprehensive safety functions such as overload protection, short-circuit protection, waterproofing, and dustproof to ensure safe use.

A. Brand goodwill

You can choose based on personal preference or a brand with a good reputation.

According to international or local national regulations, you can choose EV chargers with complete certification to ensure that products comply with regulations, such as CE, UL, etc.

Different brands have different after-sales services. You can choose a complete after-sales service plan that meets your needs so that you can use EV chargers with peace of mind.