Thinking about replacing the aux and main batteries of my 05 CDI's. How long are these batteries lasting? Anyone. Thanks.

 

I replaced the aux battery (dated 46 week of 2002) with a new one in March of this year. The main battery failed shortly thereafter. So if you do the math- about 6-1/2 years. I think several people here have averaged 7 years. My car is low option and lives in a garage in the south. Probably optimum conditions for battery life.

 

My 211 had the original batteries when it was sold, it was 6 years old. Some fail a lot earlier.