The windows on my '06 XKR were not going back up after I reset them. I knew this was most likely from a weak battery, been there before. So I removed the battery and see it's OEM. I'm thinking previous owner paid big bucks at the dealer. I was curious to see how old it was. A little Google time and found out it's stamped on negative terminal. To my great surprise it's stamped 03/05. This seems impossible.

 

Properly Maintained a battery could last that long, not that I want it in my car.
I have enough issues without the sporadic codes from a week battery.

 

My 2005 S-Type was built in May 2005 and still sports its factory battery at 83,200 miles. I check the battery cells every three months (more often during our hot and miserable summer months) and top them up with water as necessary. I believe that is the primary reason why this particular battery has lasted so long....

 

Got seventeen years on the wife's Miata sealed factory battery.

 

Original batteries supplied to car manufacturers are (I was once told by a major manufacturers agent) made to a higher spec. than the replacement market due to warranty charge back provisions- hence they last longer than replacements. Anecdotally I saw this running a mixed fleet for thirty years - originals always lasted longer than replacements, and we used the same OEM manufacturer. Deep cycles will also shorten battery life(along with heat) irrespective of source.

 

FWIW, we just discovered that the now-deceased battery in dad's 2000 S-Type was the original. So, it went ~14 years and a little over 100K miles. Spent a fair amount of the past few years on a tender.

My first thought was that it had simply been replaced with a Jaguar-labeled battery somewhere along the way (to preserve original status for Concours judging) but it was confirmed that it was, in fact, the original. Only other batteries I saw go that long were some of the Panasonic AGM's in the early Miata offerings...