The Range and Battery Problems in EVs
The range is often the most important issue when purchasing an electric vehicle. It implies how far can the vehicle travel without recharging. The estimated total distance is measured from 100% charge unless otherwise stated.
Tests that tell you how far an electric vehicle will travel on a full charge are determined under various special tests that control temperature, speed, and slopes. Many short-term and long-term factors vary according to the vehicle's specified range. The distance you can go depends on the efficiency and the state of your battery.
The movement of lithium ions in lithium-ion batteries from side to side is a critical part of charging and discharging a battery. It should be noted that the process of charging and discharging batteries is a physical process occurring in the structure of the battery and that the aging of most of the batteries is caused by the physical wear and tear of ions pushing back and forth. In short, when the ions are pushed more strongly or the temperature is higher, the battery structure can be damaged more.
Range and Range Losses
There are two types of range loss:
1) Long-term range loss is permanent.
2) Short-term range loss is temporary.
Short-term range loss is caused by external factors and is retrievable, while long-term range loss is permanent.
1) Short Term Range Loss
Short duration means that losses in the range are limited to that day, week, or season. Short-term range loss does not indicate battery health or range loss but does mean efficiency is lower than average. Reasons for a short-term loss of range:
a) Fast acceleration and high-speed driving
b) Extreme air temperature
c) Uphill or weighted driving
Acceleration and high-speed driving: The best way to keep the range at maximum level is driving in city centers and driving slowly.
When using a brake during driving, an electric car slows down and loses its kinetic energy. Regenerative braking uses the energy lost to charge the battery. Factors such as air resistance and friction are much more important in electric vehicles. According to the energy formula used, air resistance is directly proportional to the square of the speed. So if you double your speed, your energy consumption will increase four times.
Uphill or weighted driving: Electric vehicles are no different from gasoline vehicles in terms of different road types. They need more energy while accelerating or going uphill than standard driving, so you may notice a reduction in available range in case of these situations. It is more efficient while going downhill while it is the opposite for the weight as more weight in the vehicle means more energy the battery consumes.
Extreme air temperature: One of the most frequently asked questions is why EV owners witness a decrease in range when it's cold. Cold weather tends to slow down the chemical and physical reactions that keep batteries working and that temporarily reduce short-term range. However, it is actually the air conditioners that cause the decrease in efficiency. In a gas-powered car, the internal combustion engine generates a large amount of waste heat that is directed into the car to warm the passengers. However, there is not that much waste heat in an electric vehicle. The battery, therefore, needs to burn electricity to produce it.
2) Long Term Range Loss
Some aspects of long-term range loss are unavoidable, as used batteries naturally degrade over time. This fundamental degradation is due to the physical movement of lithium ions in the battery to generate electricity. This process, known as calendar aging, refers to battery degradation that occurs regardless of usage and it causes two types of deformation. The capacity reduction is due to the loss of active material in the battery. This means less lithium is available to generate electricity. This also means a decrease in performance in that lithium ions move less freely and are hindered by insignificant substances such as metallic buildup or corrosion.
There are a few things that accelerate calendar aging that occurs regardless of usage:
a) Depth of discharge (DoD)
b) High temperature
c) Fast charging frequency
Depth of discharge; It is the difference between the starting and ending state of charge when you drive an electric vehicle. Using small discharge depths helps maintain battery health, including lifespan, capacity, and power. You can charge using 25% of the battery and then use another 35% instead of using 60% of your battery before recharging to make it more efficient.
High temperature: Placing an electric vehicle under high temperature can cause unwanted chemical reactions to occur faster. These chemical effects can cause loss of lithium ions and deterioration of battery materials. Charging the electric vehicle at high temperatures increases the active power of the electric current and causes damage to the battery. The higher the temperature, the more damage occurs in the battery.
Fast charging frequency: Similar to high temperatures, higher voltages usually lead to faster reactions. This usually means that chemical reactions occur faster which causes batteries to fail. Fast charging of batteries in cold should be avoided and the charging process should be ended after 80%.
Resources: https://www.recurrentauto.com/research