The batteries are warranted for 100,000 miles or 150,000 miles depending on where you live. An "extended" warranty will cover things not included in the longer hybrid system warranty. Your TCH has a 36,000 bumper to bumper warranty, a 60,000 power train warranty and a 100,000 (or 150,000) mile hybrid system warranty.

I would not worry about the batteries. However if the A/C goes out after 36,001 miles you're not covered. If your ICE head cracks at 60,001 miles you're not covered.

This is a quality built automobile but anything mechanical can break and it's usually expensive.

For what it's worth I don't have an extended warranty but may consider the 100,000 TOYOTA extended warranty soon.