My story about a battery charger....
On my previous BMW I had every 5-6 months a new battery,the cause was a high end powerful Alpine sound system with 14 speakers and 2 subs ,and 4 amplifiers after 5 battery's I decided to buy a battery tender for overnight charging in all weekends ...the result was that the last battery I had for 14 years and was the ultimate proof that a battery charger prolongs the life time of a battery .
Now with my ///M i'm doing exactly the same thing ,and so the answer to your question is "yes" ,easely 7-8 years and more...
BTW...last winter my car sat for more than 4 months in my garage on my CTEK,don't drive with the ///M on roads with road salt and ice ,after the hibernation the ///M started just perfect,and this was another proof that a battery tender is needed for our cars !
Pics...? # 26 =>
http://www.m3post.com/forums/showthr...1#post15488771