An important question you’ll need to ask yourself if you’re considering buying a pre-owned electric car is whether the battery will work.
If you have been driving an electric car for a few years and want to ensure everything is running properly, you should make sure to make posible electric vehicle battery testing. You can perform a few simple and accessible tests at home or on a test drive if you are able to follow the steps.
We’ll share some of the options you’ve got today for testing the battery health of an electric car once you know what you’re doing.
Which battery are we talking about?
There are two batteries in an electric car:
- Battery powered by a 12-volt system that starts and powers a car’s central locking system, interior lighting, and other instruments (like any petrol or diesel car)
- This article covers the second, larger battery type (often lithium-ion) that powers the motor and drives the wheels of the car. For more information about electric car batteries, check out the following link.
What is electric car battery health?
This article, and others that discuss the health of electric car batteries, are primarily talking about their capacity compared to their new state. This is how much energy they can store.
A car’s battery capacity is measured in kilowatt hours (kWh) and varies based on its size and types. You usually find that a small hatchback battery is usually in the range of 30kWh or so, while a mid-size crossover battery is usually 60-70kWh, while a luxury and performance vehicle will almost certainly have 100kWh or more.
In most cases, the product manufacturer lists a ‘gross’ capacity for the battery of the car, which is typically higher than its ‘net’ or ‘usable’ capacity.
It is natural for the battery capacity to fade over time, usually by just one or two percent a year, but that means after a few years, the battery can’t power the car when it is fully charged. It turns out that when you charge the car to 100 percent, you drive fewer miles than you would if the battery had been newer. For now, we won’t dive deeper into the science, but the key takeaway is that older batteries tend to hold less charge than those newer ones.
Everyone’s mileage and driving style is different, so it doesn’t mean you should avoid older cars. However, knowing how much capacity a battery has will help you make an informed decision. Here are some tips for charging an electric car at home, and here are some tips for charging an electric car at home.
How to test an electric car’s battery health
Various options are available – from the easy and affordable through to the professional, industry-standard tests that require more time and money. Here we’ll focus primarily on the easy and affordable tests.
Test the battery health using the dashboard monitor. It is possible to monitor the battery’s health over time by checking your dashboard.
Range Estimation
There is usually an estimate of driving range displayed on the dashboard of an electric car. This number is usually derived from the current battery charge level and will also be influenced by driving style, terrain, and weather.
To determine your car’s battery capacity, charge it for at least six hours and then drive it, comparing the actual mileage you get with the estimated range. The battery should give you a range somewhere close to the estimate if it is in good shape.
It is common for the available range of an older car to decrease with age, so expect less; however, if the actual range is significantly off, drops significantly, or fluctuates between charges, there could be a problem with the battery. To determine the effect of the heater and air conditioning when driving, use them.
Compare your range to that of similar models of the same age by checking forums or asking other electric car owners. You’ll get a better idea of what’s acceptable and what’s not.
State of Charge (SOC) Measurement
SOC (State of Charge) is another simple method for measuring the condition of an electric car’s battery. SOC is the amount of charge left in a battery at a given time.
This can usually be found on the infotainment screen or dashboard. A battery’s State of Charge will tell you how much energy is left in it as you drive. If it is dropping a lot of voltage, you may have a problem. As you test drive, you should keep an eye out for this one.
Battery Health Indicators
There are several ways in which electric vehicles use batteries, such as Battery Management Systems (BMS), which continuously monitor their performance. In addition to providing valuable information about the battery’s temperature, voltage, and current, some battery management systems also provide an overview of the battery’s overall condition and provide you with a report.
It is important to note how long the battery takes to charge and how long it takes to deplete along with these health indicators so that you can gauge its health over time. Make sure you keep an eye on these stats and consult your vehicle’s manual to understand what they mean and whether your battery is functioning correctly.
Diagnostic Scan at Service Centres
The battery of an electric vehicle can be inspected thoroughly by a certified service center that uses specialized equipment to perform diagnostic scans.
There are a variety of costs involved with diagnostic scans, but they may prove to be a worthwhile investment. This type of test provides detailed information on the internal resistance and capacity of a battery.
Manufacturer’s Software Tools
A number of manufacturers offer software or smartphone apps that can provide you with detailed information about the battery condition of your electric car.
A typical app will require payment and will use a USB OBD2 reader (which we’ll discuss below), which will monitor and share advanced battery data, including charging patterns, battery capacity measurements, and historical record keeping.
Consider a third-party app or reader like FleetCarma that documents trips and collects statistics around your vehicle before you buy or rent one. The details provided by the app will vary, so make sure you check out your options before purchasing or renting one.
Diagnostic tools
Various diagnostic tools can determine whether a battery is damaged, damaged or out of charge, as well as check its volume, voltage and temperature.
OBD2 readers and scanners
Cars have an On-Board Diagnostics (OBD) system, and since 1996 vehicles have been using the OBD2 system to monitor your car’s functions. You can use this system for electric car batteries as well as to get a diagnosis of your car problems using Diagnostic Trouble Codes (DTCs).
If you want to read those codes, you’ll need an OBD2 scanner or reader. A standard reader will simply read them and display them, then reset the check engine light in the vehicle. The scanner, on the other hand, will provide troubleshooting tips for diagnosing the problem. For around £50, most garages sell OBD2 readers and scanners.
Multimeter
A multimeter is a handy tool that measures current, voltage, and resistance, making it useful for diagnosing problems in various parts of electric vehicles, including the batteries.
To ensure the multimeter is capable of testing an electric vehicle with open circuits and circuits, and of measuring temperatures accurately, you’ll need to do some research. Make sure the multimeter works at the correct voltage for the car you’re testing as well. Buying one can cost a couple of hundred pounds, so they’re not suitable for everyone, but they’re an option for those who are more invested in their vehicles.
Battery tester
It is also possible to buy a battery tester that is designed to detect failures or damage in electric vehicle batteries. It measures the battery’s charge, voltage, temperature, and can also test for damage to the battery electrodes.
There are different types of testers available at different prices – most costing in the hundreds. Again, these aren’t right for the vast majority of drivers, but they may fit the needs of car enthusiasts and collectors.
Prolonging your battery’s life
There are plenty of things you can do to prolong the life of your battery, regardless of whether you tested it or not:
- Make sure your battery is charged regularly and consistently, ideally keeping the level above 20% and not going over 80% unless you are driving for a very long period of time
- Battery health is best protected by slow charging whenever possible, since this produces the least amount of heat and stress
- During hot weather, park in shaded areas and during cold weather, keep the car covered (ideally in a garage)
- Keep your speed under control, avoiding aggressive acceleration and heavy braking as much as possible
- Software updates, which can optimize battery performance, are often released by manufacturers
- Regularly maintain your car, ensure that the tyres are inflated correctly, and schedule routine maintenance
- If the car isn’t used for a while, make sure to restart it. If the car isn’t being used, it should be stored in a cool, dry location with the battery charge level between 40% and 60%.
People Also Ask
1. What are the standards for electric vehicle testing?
The standards for electric vehicle testing are designed to ensure the safety, performance, and reliability of EVs. Key standards include:
SAE J1772:
This standard defines the physical, electrical, and performance requirements for EV charging systems.
IEC 62196:
This international standard covers the general requirements for EV conductive charging systems.
UN 38.3:
This standard specifies the safety requirements for lithium-ion batteries during transportation.
ISO 26262:
This standard addresses the functional safety of electrical and electronic systems in vehicles.
ISO 15118:
It defines the communication between EVs and charging stations, including authentication and payment processes.
2. How to test the health of an EV battery?
Testing the health of an EV battery involves several methods to assess its capacity, efficiency, and overall condition:
State of Charge (SOC) Measurement:
This determines the current charge level of the battery.
State of Health (SOH) Analysis:
SOH indicates the overall health and performance capacity of the battery compared to a new battery.
Capacity Testing:
Measures the total charge the battery can hold, often done through full charge-discharge cycles.
Internal Resistance Testing:
Evaluates the resistance within the battery, which can indicate degradation or potential issues.
Thermal Imaging:
Checks for hotspots or temperature anomalies that may indicate underlying problems.
On-Board Diagnostics (OBD):
Uses vehicle sensors and software to monitor battery health and performance in real-time.
3. How are electric vehicle batteries tested?
Electric vehicle batteries undergo a series of tests to ensure they meet safety and performance standards:
Performance Testing:
Includes cycle life testing, capacity testing, and efficiency measurements to evaluate how well the battery performs under various conditions.
Safety Testing:
Includes thermal stability tests, overcharge and over-discharge tests, short circuit tests, and crush tests to ensure the battery can withstand adverse conditions without posing risks.
Environmental Testing:
Exposes batteries to extreme temperatures, humidity, and vibration to simulate real-world conditions and assess durability.
Electrical Testing:
Involves testing for voltage, current, and resistance to ensure proper electrical function and safety.
Chemical Testing:
Analyzes the chemical composition and reactions within the battery to ensure stability and performance.
4. Who tests EV batteries?
EV batteries are tested by various entities, including:
Manufacturers:
Automakers and battery manufacturers conduct extensive testing during the development and production stages to ensure quality and compliance with standards.
Third-Party Testing Laboratories:
Independent labs perform standardized testing for certification and validation, such as Underwriters Laboratories (UL), TÜV, and Intertek.
Regulatory Bodies:
Government and international regulatory agencies, such as the National Highway Traffic Safety Administration (NHTSA) and the International Electrotechnical Commission (IEC), set and enforce testing standards.
Research Institutions:
Universities and research centers contribute to advancing battery technology and safety through experimental testing and studies.
These entities ensure that EV batteries meet the necessary standards and are safe and reliable for consumer use.
