All You Want to Know About Electric Vehicle Battery

Electric Vehicle Battery Aging and Advancement

As the automobile industry is getting advanced, it is expected that the Electric Vehicle (EV) adaption is going to accelerate in the coming decade. Major concerns of the EV industry is; improved manufacturing, lower pricing, and public awareness. The Electric Vehicle (EV) introduces new demands on their battery with these new responsibilities, the modern energy source works extremely well. A question may arise in your mind that why does a phone battery have a life span of three years while that of an EV is 10 years or more? Nobody knows the answer, but progress and advancement have been made in the industry regarding this scenario. The matter of economically storing electrical engineering is still an unsolved challenge in the modern era. You already have the idea that the battery is the main component of the EV. You will understand some basics of the battery in this article with the realization of some factors that are responsible for the aging of the battery and some developments being made for the betterment of EV batteries.

Electric vehicles (EV) uses traction motors for moving force. These vehicles may be powered through off-vehicle batteries or may contain an electrical battery, fuel cells, or solar panels to convert fuel to electricity. This technology was introduced in the 19th century and for years it has been used to power trains. In modern times, with the increased focus on renewable energy and reducing carbon footprints, electric cars have come to the spotlight. Tesla, Nissan, and Chevrolet are top companies in this new emerging trend. These three companies sell 60% of all-electric vehicles in USA and this figure is expected to increase as climate change and global warming became a major focus.  Another biggest advantage of cars running on the electric battery is that they’re low maintenance, thereby ensuring increased efficiency and performance.

Different types of electric batteries have different travel range and efficiency. The lead-acid battery is most available and inexpensive and is capable of up to 130 km per charge. Following this, nickel-based batteries have higher specific energy than lead-acid and can have more than 200 km of range. Finding the economic balance of range, performance, battery capacity, and weight pose challenges to any electric vehicle manufacturer.

What Are the Main Components of Electric Batteries?

A car battery powered by gas is six-cell component. This battery on average weighs 41 pounds. In the Tesla Model S, the 85-kWh lithium-ion battery pack consists of 7,104 cells and its weight is roughly 1,200 pounds. With an incredible range of 265 miles, the battery takes 3.5 hours to recharge at 220V that is when the battery is fully exhausted. For an internal combustion engine-powered vehicle, that is much longer than a fuel halt.

The battery pack of electric vehicles are complex and vary widely for each designing company. They combine many individual cells connected in series and parallel to achieve the optimum voltage. Electric batteries for vehicles can contain several hundred cells which are grouped into smaller stacks called modules and then several of these modules are placed in a single pack. The battery packs also contain DC contactors/relays, which connect the battery cells stack to the main positive and negative output terminals of the pack. It also has a variety of temperature, voltage, and current sensors to regulate the environment.

The recharging power can be connected to the car with direct coupling. This means, that it transfers electrical energy using physical contact via a conductive medium. The second way of recharging is inductive charging, which uses electromagnetic induction to provide electricity to car.

Charging Mechanism with the Age of the Battery

You gulp the food quickly when you’re very hungry, this is how the human body works. The charging mechanism of the EV works the same way. The charging process is most beneficial for the EV when it has a very low charge. The charge acceptance of the battery decreases with the saturation. The charging process takes place such that it extracts and, introduces lithium from the cathode on the anode.

Most people opt for fast charging as well. The boost charging or ultra-fast requires proper conditions for the charging process. The efficiency of the charge depends on the battery temperature and system of a charge (SoC).  The charge rates decrease eventually due to the aging of the battery, poor balancing of the cell, and internal resistance.

When you get old, you will be able to run a marathon but depending on your stamina and controlled exertion, similar is the case with the battery.  It is difficult to estimate the optimum charging current level, successful battery diagnostic skills are still being developed. It concludes that a smart charger should be able to understand the state of health (SoH) of the battery and apply the current for the charging process accordingly, in order to let the battery, absorb reasonable charging. We have some specific rates for the charging level that are defined according to the current supplied per hour.

       The reason behind the long-life EV battery is due to the sizing and its operation in the middle range only, while the ‘grace capacity (capacity that is not being used) is spared in large amount in the lower and upper bands. Partial usage decreases the stress over the battery, but valuable energy goes underutilized or wasted.  The problem of oversizing is that it increases the weight and the cost, but the unused capacity eventually be utilized when the actual capacity weakens.

In the new EV cell, charging and discharging the battery to only 80% and 20% respectively, just utilizes 60% of the power. The charge acceptance declines with usage and time, in order to reach the driving range, the onboard Battery Management System (BMS) needs a higher charge and a lower discharge. The driver is unaware of this change until a decrease in driving range is detected. This happens as it utilizes the “grace capacity.”

Theoretically, to satisfy the energy needs, depletion requires a maximum charge and maximum discharge. At this point, the tension of the battery increases, and power starts to fade, resulting in a decreased driving range. This transition is predictable and takes a few years of driving to develop. The EV will also be used for quick commutes and errands until the battery power has fallen to 70%. Capacity fading only decreases the driving range in most cases when power remains stable.

For the 160,000km drive limit, there is an assurance of 8 years of battery life. Automakers are trying to extend the overall warrant to almost 10 years. By 2020, the United States Advanced Battery Consortium (USABC’s) has set a target of 1000 cycles for 15 years. For 250 km daily, 2000 cycles with an overall 500,000 km are considered a good approach for an EV battery. Many experiments have been performed regarding this research and acceptable outcomes have been observed. 

       The aging of batteries is dynamic and not necessarily predictable. The battery usage is a function of age, count of cycles, speed of charge, levels of load and temperature. Extensive experiments with simulating batteries in an EV were performed by the University of Munich (TUM). In a 18650 box, the prototype battery is an NCA Li-ion, the same cell used in a Tesla EV. This cell’s cathode content is nickel, aluminum, and cobalt, anode material is graphite; 18640 determines the dimension of the cell, which is 64 mm in length and16 mm in diameter.

Can I Do Fast Charging More Often?

The value of time is so important nowadays that you don’t want to wait for anything that is taking time above your tolerance level. In this case of EV as well, you would want to go for fast charging to save time. But everything has its own advantages and disadvantages.  If you chose to ultra-fast charge your EV more often, this will let the BMS decrease the current by a few KWs. On the Supercharger, instead of 120kW, the charging may decrease to 90kW, increasing the charging time of the battery by 5 minutes. This adjustment is made by the EV manufacturers not to demotivate for the option of fast charging but for the safety and long life of the battery by adjusting the conditions according to the battery’s requirements.

What Is the Effect of Temperature on Battery Charging and Discharging?

Everything around you gets affected by the temperature, same is the case with charging and discharging of the battery. The temperature of the battery influences how fast or slow is the speed of the charging or discharging. Li-ion Battery always favors a cold storage temperature but charging and discharging get the best results at high room temperature. A battery charges at 40 ° C (104 ° F) in one hour as compared to one hour and thirty minutes at 5 ° C; the packs, however, degrade faster. At a very high temperature such as 50 ° C, the charger switches to a half-power supply for safety reasons. When charging under freezing, charging power must also be kept limited because low-temperature usage contributes to anode deprivation.

When working at a moderate temperature, the life of a Li-ion battery is extended. For charging and driving purposes, the EV battery should be warmed up to a suitable temperature of about 25 ° C (77 ° F). This contrasts with 10 ° C (50 ° F) storage or parking. Stress is triggered by charging and working Li-ion at low temperatures, this is a type of concept that can’t be applied to other chemistry phenomena.

So, the characteristics of the aging of the Li-Ion battery are complicated and comprises of charging levels, charging depth temperature, and charging speed. The overall battery life depends upon the combination of multiple events that happen during the usage of battery including the environmental conditions.

What Is the Concept of C-rate in Charging?

The C-rate is indicated as the charging and discharging rate of the batteries. The charging capacity of the battery is rated as 1C, which interprets as the 1Ah rate for a fully charged battery which means for one hour, it is going to provide 1A of current.  After discharging the same battery is going to have a rate of C/2, for 2 hours it should provide 500mA. Similarly, 2C will provide 2A for half an hour. Fast discharging reduces the discharge time and the same losses also influence charge times. 

 Summarizing the rates and discharging time, 1C is known for one-hour discharge; C/2 is two hours discharge and C/5 is a five-hour discharge. With reasonable stress, some high-end batteries can be discharged even above the level of 1C.


What Are the Charging Levels of the Li-ion EV Battery?

The charging of the energy cell should be done below the 1C rate. At 1C, currently equal to the Ah rating of the battery, the Li-ion battery is charged around 90% in one hour. At 1C, charging 85kWh battery pulls 85kW power, consuming the capacity of five typical households. The electrical energy that 3-5 households absorb a day is included in an 85kWh battery.

How Can You Prolong the EV Battery Life?

There are simple tips that you can follow to prolong your EV battery life. Limiting the fast charging option specifically, when it is cold can help increase your battery life, use Level 2 charging instead. It is better to charge the battery up to the required level, for daily routine. Side by side does not discharge the battery fully.  Try to use and charge the battery at room temperature. The functioning of the battery in cold reduces its capacity.

Some Restrictions of Electric Batteries

We need to overcome few hindrances to make this technology more achievable for the common man. This means, that, new features should be included to reduce the effects of the problems. One of the biggest disadvantages of electric batteries is that many of them require protection from being charged and discharged and have currently maintained within safe limits. Another shortcoming of electric batteries is that they suffer from aging. They need to be constantly replaced and this becomes even more difficult when the battery is embedded in the vehicle’s system. In addition to this, many electric batteries, including the most famous of them, such as lithium-ion batteries age, whether they’re in use or not, further affecting the efficiency of the battery.

Transportation costs are another biggest drawback of electric batteries. They cannot be carried on airplanes in bundles, so their transport is limited to ships. On the plane, any lithium battery needs to be shielded from short circuits and this is particularly important for large power banks. Another drawback of electric batteries that prevents them to be attained by a common man is that they’re extremely costly, and then add to this cost of other components of the car causes a common man to keep up with the normal gas-powered cars instead of switching to electric vehicles.

Developments and Research

These are the few restrictions in the battery-operated cars that might be preventing you from buying it. But here is good news for you, as it is mentioned before, these are limitations that need to be recognized and fixed, and since many major companies are interested in investing in this technology, one can be hopeful that in near future, these obstacles can be removed. So, let’s see what new developments in this industry are.

Lithium Iron Phosphate Batteries in EVs

LiFePO4 is the most famous member of the family of olivine-type lithium metal, and it is one of the emerging contestants for the cathode of lithium-ion batteries. They have lower energy density then mainstream lithium cobalt oxide and also lower operating voltage. It was made as a cathode in the electric battery in 1996 because of reversible extraction and insertion of lithium from the base  Because of its low toxicity, low cost, natural abundance of iron, safety characteristics, and higher thermal stability, it has become more popular in the marketplace. It does not have nickel or cobalt, both of which are associated with high risk and immoral mining conditions and have high production and haulage cost. One of the obstacles was low electrical conductivity and many scientists are trying to overcome this problem by using more efficient conductive materials such as carbon nanotubes. The energy density of the LFP battery is much lower than lead batteries. This makes it suitable for forklifts, motorcycles, and electric cars because of the higher discharge rates, lower weight, and longer life.

Glass Batteries in EVs

A team of scientists led by Nobel prize winner; John Goodenough submitted a patent with a new battery that uses glass as a key component. This works by spiking glass with sodium or lithium to form an electrode so, that it provides three times the energy storage capacity than a lithium-ion battery. The biggest advantage of this battery is that it is neither explosive and unstable and does not present any issues of lithium dendrite growth, which causes short circuits. The best thing about this invention is that it can break the price barrier that hinders the uptake of electric cars. In addition to this, it can be used to store intermittent solar and wind power on electric grids. The most hopeful news is that it can have more than average 1000 discharge cycles of lithium-based batteries. Admittedly, this new technology feels too good to be true but a scientist like John Goodenough holds high regards in the field of electric batteries, so it can be safe to assume, and hope glass batteries can become a significantly groundbreaking reality in the future.

Lithium-Sulphur (LS) Batteries in EVs

In addition to Lithium Phosphate batteries, LS batteries are becoming more popular because they replace heavy metals that are considered dangerous for the environment. The low atomic weight of both lithium and sulphur makes it relatively light. This was used in the longest solar-powered air flight. These batteries may replace lithium-ion batteries because of their higher energy density and reduced costs. Also, they offer significantly better specific energies then lithium-ion batteries. However, there are many issues with LS batteries that hinders its emergence in the marketplace. The biggest problem with this is that it produces progressive leakage of active material from the cathode, resulting in a low life cycle of the battery.

Future of Electric Vehicle Batteries

A US owned business intelligence firm says it is a base case scenario for electric vehicle adoption would see fully electric vehicles to account for 14% sales in 2030. Another analyst said this figure could rise to 70-80% if on the move charging issue can be addressed in the next decade. It is expected that lithium-based battery density can rise up to 30%, with the advancement in the above-mentioned technologies and this, in turn, will supply further advances. In addition to this, there is an emerging new component of dynamic electric vehicle charging. This means that vehicle is run on solar batteries, and it takes energy directly from the sun to power the battery. This is done by a start-up in the Netherlands and it is expected that this technology would advance in the coming years. This technology would ensure that car is run on 100% clean energy.

Many funding and research from renowned technology companies such as Volkswagen, BMW Group, Tesla, and Daimler have been made into solid-state technology. These investments highlight how important these technologies are. In addition to the above-mentioned technologies, silicon-based batteries are also emerging in the field because of the promise of low range anxiety.

The future of the electric car market and the speed with which consumers are switching from petrol and diesel vehicle in favor of cleaner replacements will depend on cost, safety, driving performance, and the time required to recharge the battery.

Many things need to happen. Many advancements need to be made, and there are features in the success of this technology that is still not practiced. But seeing with how much enthusiasm and vigor scientists are working on this technology and investors are pouring money into this technology, it is safe to say that the potential for future advancements is boundless.