Two problems related to battery dead have been reported for the 2017 Toyota Highlander. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2017 Toyota Highlander based on all problems reported for the 2017 Highlander.
Five different times failure to start the engine and battery appears drained with approx. 30k miles. Each time the vehicle was stationary and either in my garage or parked. Jumper cables used to start the car did the job the first two times, then a powerful portable battery jumper was needed the next two times and the battery was replaced by aaa - told me the oe battery failed (not under warranty, so it cost me out of pocket. Now, the 5th time I am waiting for aaa again. Their battery is still under free replacement warranty. This is very poor performance for a (I bought new) car that has just over 35k miles and less than 39 months old. Also, seeing all the electrical problems and a recall for the 2020 same model, leads me to believe Toyota is not as reliable as they once were.
The battery failed after we owned the car for 2 yrs and 11 months (mileage ~44,000). The replacement battery cost about $450 including installation. This is excessively early failure, and we are out a large amount of money for something that should not have happened with this new of a vehicle. It took 1 month to get the replacement battery. Also excessive.