EV Battery Health Check

We are conscious that knowledge is key, particularly when browsing DoneDeal for a used EV so let's elaborate a little more on our recent  EV Buying Guide by taking a deeper look at the battery health check diagnostic procedure and what it entails. The transition to electric powered cars is happening at pace and we believe any apprehensions surrounding batteries and how long they last, should be addressed.

Who carries out an electric vehicle battery check?

If you are buying a used EV from a genuine franchised dealer, they will invariably have the diagnostic tools and software that are used to connect to the vehicle's onboard computer system. There are now a growing number of independent specialists or service centres, which also can conduct this test in house or by using portable diagnostic devices.

What does the diagnostic tool or software do?

It essentially allows the user to talk directly with the Battery Management System (BMS). The battery management system monitors various parameters of the battery, including state of charge (SoC), state of health (SoH), temperature, voltage, and current. It can evaluate the battery's capacity and compare it to its original capacity when new helping to determine the extent of any degradation. Capacity is a key indicator of how much charge the battery can hold and deliver. Monitoring the voltage of individual cells within the battery pack is also important because Imbalances can indicate potential issues with specific cells, which might affect overall performance and lifespan. It will also show the temperature profile of the battery to ensure it remains within optimal operating ranges. Overheating or significant temperature fluctuations can indicate underlying problems.

What will the battery health report look like?

The battery health report will naturally show some level or degradation but ultimately you are looking for no cause for concern or peace of mind that your battery still has plenty of life or warranty left. Generally degradation of up to 20% over the first 8 to 10 years of use is considered normal and acceptable in the EV industry.  The number of charge and discharge cycles the battery has undergone plays a factor in this. High cycle counts can contribute to degradation or use predominantly of high voltage fast chargers. The report will look at any error codes or alerts generated by the BMS, which should indicate issues such as overheating, overcharging, or cell failures. Remember, even if there is a problem, all is not lost! Many batteries now have individual banks of cells and cooling systems that can be easily replaced.

How important is it to stay on top of software updates?

The importance of keeping an electric vehicles software up to date, is paramount. There are a number of ‘over the air’ software updates that are sent directly to electric vehicles all over the world. A simple tap of the button when asked to do so, will allow these to take place in much the same way that you would update your mobile phone software. Sometimes dealer intervention is required where the update is more significant. Keeping the battery management system software updated will improve efficiency and address any known issues. Glance at the owners manual from time to time to make sure you are staying on top of the recommended user guidelines and schedule services as and when needed.

What’s should you expect at the end?

After the health check, a detailed report is usually generated, providing insights into the battery's condition, any detected issues, and recommended actions. Regular battery health checks can help maintain an EV's performance, extend its battery life, and ensure safety. Don’t be alarmed if a test drive is needed. Sometimes simulating driving conditions to assess the battery's performance under load is needed. This helps evaluate how well the battery maintains power delivery during actual usage. From calling a few our trusted DoneDeal EV dealers, we have heard positive reports of vehicles coming back in with 100,000 kilometres still showing 90% of battery life remaining. This is all just about peace of mind, and dispelling some battery myths that are currently in the Irish media. There is eveidence to suggest the modern EV battery can last just as long as a combustion powered unit.