I just bought a 2004 XC70, its my first Volvo and first European car. I was surprised to read in the manual I found online that this thing uses a water battery!

While sitting in the driveway today with the door open and key in position 2, the text message screen said the battery was low, after only 5 minutes or so.

I unscrewed the 6 cell caps on the battery and could only see significant water levels in 2 of them. Should I fill the others? Is there a danger of over filling? How high up should the water go?