What is the expected Battery failure frequency, life of a battery in a 750ix?

Hello, automotive batteries can last anywhere from a year or two to seven or eight years. It really depends on so many different factors, which cannot be fully listed here. Safe to say: if you have an original battery in this vehicle and it is approximately 6 years old -- you can say you've gotten quite a value out of that battery, and it wouldn't be a bad idea to proactively change it.