Battery's last an average or 6 years in these .
The IBS system can cause all kinds of unrelated problems
when the battery is low.
Read about the IBS in the first electrical pdf
electical e90 pdf
http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU