Owner of a hybrid electric vehicle is concerned about battery life


Jack W. writes by email:

“I have a 2018 Toyota Avalon hybrid with a nickel-metal hydride (NiMH) battery. I generally keep cars for many years. I am concerned that the battery may give out before I may wish to replace the car. I understand that battery replacement would be very expensive. In the event the battery did give out, is it possible that the car can be transformed to run on the existing 4-cylinder gasoline engine only? If so, how would the cost of transformation compare to replacing the HV battery? Thanks for your input. Enjoy reading your column.”


Thanks for writing. Your high-voltage battery has a 10-year, 150,000 miles warranty. They are very reliable and I have known them to last over 10 years and 300,000 miles. While the high-voltage battery does lose some capacity over time, this just results in slightly lower fuel economy.

Almost any shop or dealer can use a scan tool and check on the status of the battery by looking at the difference in voltage and internal resistance of individual modules. It is expensive to replace the high-voltage battery and many experts recommend purchasing a new high-voltage battery from a Toyota dealer if, or when, it has been proved to need replacement. Even though the high-voltage battery is degraded, the vehicle can still function by using the gasoline engine more than usual resulting in reduced fuel economy. I own two hybrid electric vehicles myself and one is ten years old and is still in good health. Don’t worry about it and just enjoy it.

Have an automotive question? Get a straight answer by writing to Jim at jim@jameshalderman.com