Guide to Testing Tesla Battery Health and Checking Degradation
Tesla provides a simple tool for owners to monitor their vehicle’s battery health and improve range estimates.
Battery Health Overview
Electric vehicle batteries naturally degrade over time due to charging and discharging cycles. Factors like the number of charge cycles and how long the battery stays at low or high states of charge contribute to this degradation.
Battery health indicates how much of the original energy capacity remains. For example, a battery at 85% health has lost about 15% of its capacity, resulting in a roughly 85% range compared to when new.
Battery Degradation Process
Battery degradation is most significant in the first few months of ownership, with an initial decline of 1-3% as the Battery Management System (BMS) recalibrates for accurate range and charging capacity estimates. Tesla states that batteries generally degrade at a rate of about 15% per 200,000 miles, with the first year accounting for around 5% of this degradation.
Modern EVs have more accurate BMS systems, reducing concerns about battery degradation.
Tesla’s Battery Warranty
Tesla offers a warranty covering the battery and drive units, replacing the battery pack if health drops below 70% while under warranty.
Warranty details vary based on Tesla model and configuration.
How to Conduct a Battery Health Test
Tesla provides a user-friendly method to test battery health through the Controls > Service menu.
The test requires the vehicle to be plugged in for up to 18 hours, with specific requirements such as battery level, charging speed, and connection to an AC charging station.
Running the Battery Test
The test involves discharging and charging the battery to calibrate the BMS, with the vehicle running motors and heat pumps to aid in the process.
After completion, results can be viewed in the Tesla app or vehicle settings.
Interpreting Results
Most vehicles show a degradation range between 10-20%, based on charging habits and battery use. Results below 70% during the warranty period may warrant a replacement.
It’s important to note that after the test, the vehicle’s range estimate may adjust for a more accurate reading.
Note: Maintaining the battery at 100% charge post-test is not recommended for battery health.
It would be a beneficial enhancement for Tesla to automatically use up energy to bring the battery level back to the charge limit if the vehicle has been unused for an hour or two.
It is not advisable to leave your vehicle at 100% battery unless you have a LFP battery. It is recommended to plan a drive soon after the battery test completes. If driving is not possible, it is suggested to run the climate system to consume some energy.
Test Limitations
Due to the fact that Tesla’s battery test depletes and recharges the battery, it is best to avoid performing it frequently. Tesla limits the battery test to once every six months, unless you access Service Mode to conduct the test.