The Impact Of DC Fast Charging On Electric Vehicles Battery

Date:2022-12-2 Category:News

Introduction

Electric vehicles are a growing part of the automotive market. They have many advantages over traditional gasoline-powered vehicles, including lower maintenance costs and increased safety. DC fast charging is currently one of the fastest ways to charge an electric vehicle. The technology uses an industrial fast charger to provide an electric vehicle with a large amount of electricity quickly.

Such high voltage and current loads can have a negative impact on the battery, which manufacturers usually try to avoid when designing green cars. However, this is not always possible in real-world conditions.

For example, making frequent stops at charging stations might not be possible during a long trip.

However, improved battery technology could bring DC fast charging of electric cars closer.

The article describes how batteries are affected by DC fast charging, and the impact of this issue on the design of future electric cars is discussed.

1. What’s the electric vehicle battery? How does it work? 

All electric vehicles have batteries to store and supply the energy needed for driving. The battery in an electric vehicle can be compared to the tank in a gasoline-powered car: it provides energy.

The most common type of electric vehicle battery is lithium-ion. Lithium-ion batteries are rechargeable and strong enough for use in electric car applications.

The Impact Of DC Fast Charging On Electric Vehicles Battery

They can start a vehicle and run its power systems, but also provide extra power for acceleration and assist in regenerative braking, where the energy produced from breaking moves back into the battery rather than being added to road resistance.

Without this process, much of the energy created while braking would be lost as heat, which is why it needs additional power.

There are different lithium-ion batteries, including the 18650 laptop battery, with the numbers referring to a standard shape and size. Lithium-ion is also used in other applications like phones, power tools, and many other items.

Lithium-ion comes in two main types:

Lithium Cobalt (LiCoO2) and Lithium Manganese (LiMnO2).

The main advantage of lithium cobalt batteries is that they can supply higher currents than lithium manganese batteries. However, there are different grades of cobalt, which affect the battery’s performance.

How does it work?

A typical electric vehicle has three main systems: the motor drive system, the battery, and an energy conversion system. The motor drive is powered directly from the battery, which charges from various sources, including fossil fuels, renewably generated power, and direct solar power.

If charge levels fall below a certain voltage, the car cannot run and will not move.

The battery’s main function is to provide current for acceleration or extra power for regenerative braking.

The energy conversion system converts this electrical energy into mechanical energy via its power control unit.

The Impact Of DC Fast Charging On Electric Vehicles Battery

This mechanical energy is the force that drives the wheels, which are attached to a gearbox and turned into torque for driving the car. The gearbox sends this mechanical power to the wheels via its axle.

Every electric vehicle has its power control unit. This enables an electric vehicle to have different characteristics like acceleration and regenerative braking, depending on how it was designed.

2. What’s the DC fast charging

DC fast charging brings electric vehicles back up to 80 percent charge in just half hour by providing a very high current, enough energy can be transferred to the batteries in an hour or less compared with 6 hours if using a general AC charger.

Separate AC and DC fast chargers will work with both types of cars, but generally, an outlet has a combined power output of 150 kW. In contrast, dedicated DC fast charging stations can have a significantly higher power output.

With current technology levels, after a full charge or recharge, a lithium-ion battery can last approximately 1500 cycles before it reaches the end of its life cycle. The batteries used in electric vehicles can degrade very quickly in the event of over-discharge or overcharge. If below 50 percent, they will not be able to start the vehicle and lose much of its capacity.

DC fast charging imposes a large amount of stress on the battery. When an electric vehicle is connected to a DC fast charger, the current required for recharging can be significantly higher than on a standard 230V charger.

A typical lithium-ion battery stack has hundreds of cells; many of these are only used for balancing (balancing allows energy to be transferred efficiently and reduces wasted power).

Current lithium-ion batteries are designed so they can recover quickly when recharged. This is because the energy required to be added to the cell during recharging is greater than its absorption capacity.

Charging a battery that does not have this feature will take as long as standard charging. In other words, discharging the battery a lot before charging it again will not harm it or cause it to become less efficient than if it were used properly.

3. Does a DC fast EV charger affect the lifespan of the EV battery?

Using a DC fast charger to charge your EV battery degrades the battery life faster than using AC chargers. The lifespan of your EV battery depends on the charging cycles. These are the cycles between a fully charged battery and a discharged battery.

The more cycles, the more loss of life. However, the more cycles you can use, the longer your EV battery is effective. It doesn’t mean that these extra cycles are “green” if your battery isn’t completely depleted.

Lithium batteries use a unique charging technique that involves the flow of lithium ions from the battery’s negative electrode to the positive electrode. During fast charging, the DC fast charger forces the lithium ions to flow at a higher speed, which causes an imbalance in the positive and negative electrodes. This imbalance causes the negative electrode to start degrading because there are more positively charged ions than negative ions. The more the battery is charged with a DC charger, the faster it degrades due to polarization. This also means that if electric vehicles are used for long distances and charged in places with fast chargers, their batteries will lose their capacity faster.

However, this does not mean DC fast charging causes the EV battery to lose its charge faster than its standard AC charger. Even with a DC fast charger, lithium-ion batteries can last about 1500 cycles before they theoretically stop working effectively. In theory, Lithium phosphate batteries can last for up to 2000 cycles.

Although DC fast charging affects your battery’s overall lifespan, other factors such as climatic conditions, vehicle usage, and charging cycles are involved.

Newer batteries can compensate for higher charging rates, reducing the impact of these stressors on battery life.

A critical aspect is how batteries are specially designed when they leave the manufacturer to be installed in electric vehicles.

An important factor is whether they are mounted into a sealed unit or whether they are mounted into an open case with a negative pressure inside it (like an air bubble).

The low density of lithium-ion battery cells in open units may increase internal stress and shorten the battery’s lifespan.

The high temperatures that occur during the charging and discharging of batteries need to be managed very carefully.

The lithium-ion battery contains some liquid and solid materials, which is highly flammable.

To avoid this, care must be taken during the manufacturing process to seal the cell and prevent water from contacting its electrodes.

Maintaining a certain amount of pressure inside the cells is necessary so that gasses do not enter. This is done by providing negative or ‘back’ pressure inside the cell, so an air bubble is trapped inside it. This helps ensure that any gasses do not enter the cells when charging them at high rates.

Conclusion

The main benefit of using a DC fast charger is the fast charging time. Using a DC fast charger is okay, but it is not advisable to use it always. This ensures your battery lasts longer. Following the charging cycles of your EV battery is also essential because it ensures it is not overcharged.

Although there are no specific rules to tell you how often you should charge your car’s battery, some rules can be applied to avoid damaging your battery and extend its lifespan effectively.

Here are other tips that can help you prolong the life of your EV battery:

1. Not charging in time: Electric vehicles should be charged in time before the power is lower than 20%, otherwise the battery will be over-discharged, which will directly affect the service life of the battery;

2. Frequently fully charged: Frequently charging the battery of an electric vehicle will also cause the battery to be overcharged, which will reduce the life and capacity of the battery over time;

3. Irregular charging: If you often use electrical equipment such as air conditioners when charging the vehicle, it will increase the load inside the power battery and shorten the battery life. The vehicle should be kept off during charging, and it is best not to stay in the car .

If you have the opportunity to install a personal charging pile, try to install it as much as possible, and charge slowly if you can. If there is only fast charging available outside, then try not to let the power drop too low, and the remaining 20-30% can be ready to charge. At the same time, don’t pursue full charging when fast charging, and you can draw the gun after charging to about 80% First, the trickle charging after 80% takes too long, and second, it can also actively prevent the battery from overcharging and battery overheating

Over the past decade, rapid development in EV technology has made it possible for more and more cities to follow advanced city’s lead in building large numbers of charging stations within the urban area. This trend is expected to continue over the next decade in all these cities.

The high cost of car batteries means that a full transition to electric vehicles is not expected anytime soon.

There are also several technological, geographical, and infrastructural barriers to adopting electric vehicles.

However, one crucial element for reducing greenhouse gasses generated by transportation-related activities is the expansion of EVs and DC fast chargers within urban areas.

With the development of large numbers of charging stations at municipal levels, there will be a significant reduction in greenhouse gas emissions compared to the combustion engine-powered transportation modes.

To achieve this goal, it is important to understand how EVs interact with their urban environment. Doing so will help cities to develop a vision for how these chargers can better serve urban residents, as well as create an adequate policy and institutional framework to support the expansion of Electric Vehicle infrastructure throughout cities.

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