I have a 2006 xc90 4.4L. I've noticed symptoms over the past few weeks of a weak battery. Today it failed to start so I went to the parts store to get a new battery...The guy asked me if I had the electrical upgrade? Wasn't sure but there were 2 options for batteries a normal sized 600 cca unit and a unit about 4inches longer rated at 950cca...I had the cover on so wasn't sure of what was in there. Had the smaller original vovlo unit. Got the bigger battery and it went right (there were 2 mounting holes of the battery hold down to fit either the small or large battery). I'm curious if the electrical upgrade refers only to the battery and nothing else...also was the larger battery a factory option? You'd think the the 4.4 would come with the bigger battery.

 

Typically, the larger battery are for colder climates. There is not typically a paid upgrade you can get, its more where you live. The higher the CCA the better in my opinion. This will not last longer than the smaller one, but if you drive to the north, you wont have issues starting on the larger battery, but may have issues with the smaller battery.