How to check EV battery health?

Electric cars are gradually filling our roads. In just a few years, electric cars have gone from being a novelty to a mass mode of transport. One of the arguments in favour of buying an electric car is that there is no need for regular maintenance. At the same time, the operation of electric cars poses new challenges for their owners. Everyone knows that any battery loses its capacity over time. Therefore, the remaining autonomy time and battery life – the main thing that owners of electric cars have to worry about. Since an electric car's traction battery is the most expensive part of the battery, let's look at how to check its condition.

Criteria for assessing an electric car battery

There are two generally accepted criteria for assessing the condition of any battery:
1. SOH (State Of Health) – the remaining capacity of the battery, which is expressed as a percentage of the nominal capacity.
2. EOL (End Of Life) – the criterion indicates the end of the battery's life cycle, calculated in relation to the number of charge/discharge cycles completed.

The first criterion is the main one because it gives an insight into the current state of the battery. Reducing SOH in practice leads to a reduction in the mileage of the electric vehicle after charging.

The second EOL criterion informs us that after a certain number of charge/discharge cycles, the battery can lose its capacity dramatically. In practice, this parameter is very difficult to evaluate. The reason for this is the randomness in the discharge/charge mode of the battery.

Tools for self-determining the condition of an electric car battery:

• Range estimation;
• Charging efficiency;
• Diagnostic tools of the vehicle itself;

The first way to assess the health of an electric vehicle's battery is to monitor the vehicle's range. Range estimation takes into account factors such as driving style, terrain and weather conditions. If you notice a significant drop in current range compared to the nameplate value, it's a clear sign that the battery is deteriorating.

If you notice a significant drop in current range compared to the nameplate value, it's a clear sign that the battery is deteriorating.

Consider the electricity consumption required to fully charge an electric vehicle battery. Increased charging costs can also be an indication that the battery is deteriorating.

An increase in electric vehicle charging costs can also be an indication that the battery is deteriorating.

Many electric vehicles are equipped with diagnostic tools or software that provide information about battery health, such as the Leaf Spy app for the Nissan Leaf. Such tools can provide insight into battery voltage, temperature, cell balance, and other important parameters. Studying your vehicle's owner's manual will help you understand what diagnostic features are available and how to interpret the data to assess battery condition.

Determining the condition of an electric car battery with professional diagnostic tools

Service stations use specialised diagnostic scanners that can read the battery management unit (BMS) of an electric vehicle. For example, Consult 3+  – is used to work with the entire range of Nissan electric cars and hybrids, LOKI — works exclusively with Tesla electric cars, Xentry Diagnostic — dealer diagnostic tool for electric cars and hybrids from Mercedes. These tools allow workshop technicians to read data from which to infer the condition of the battery.

Xentry Diagnostic — a dealer diagnostic tool for electric cars and hybrids from Mercedes.

In the last few years, technology has been developed to diagnose and predict battery health using artificial intelligence. The essence of this way of checking the condition of a battery is as follows:

Artificial Intelligence (AI) is the key to battery health.

• A special device is connected to the vehicle's OBD port.
• Then a static test is carried out, during which the necessary diagnostic data is read.
• After that, a dynamic test is carried out, during which data is collected during brief acceleration of the vehicle.
• Finally, artificial intelligence is used to analyse the collected information and conclude on the current state of the battery. 

Detecting the state of an electric vehicle's battery in the event of a battery failure

The battery of an electric car can fail like an internal combustion engine in a classic car. In this case, a MS800 tester is used to determine the condition of the battery. This tester determines the capacity of each battery module and based on the results of the measurements, a trained technician makes a conclusion about the condition of the battery as a whole. Checking the battery electric car tester MS800 helps to determine which battery cells have lost capacity. That further gives an understanding of how to repair it and how much it will cost.

Closure

Methods for assessing the battery health of an electric vehicle are constantly improving. It is now clear that the battery management system (BMS) plays a crucial role in assessing the condition of the traction battery of electric vehicles during operation. And regular periodic monitoring of the battery condition will increase the service life and safety of electric vehicles. In the event of a battery failure, testers such as the MS800 are already available that can perform a battery check.