When I started driving pretty much every car battery said either "maintenance free" or "sealed for life" on it. That was to distinguish them from the old fashioned batteries where you were in charge of maintaining the level of the battery acid. I don't think I've seen that written on a battery in a decade or two and I haven't had to top up a battery in all the time I've owned my own cars. Or so I thought.
After about 3 years the battery in my
Caterham failed. I bough a new one and didn't think much of it because the car
lives in a cold garage for the whole winter and isn't used. So that I wouldn't
have to buy another battery so soon I also bought a posh battery charger and
conditioner (made by CTEK). Another 3 years have passed and when I came to
service the Caterham the battery was dead. Not only dead, but as it turned out - bone dry. After £85 and a humiliating lesson in battery maintenance I now
know that the battery in my sports car is not maintenance free and that I
should have been topping it up every 3 months. Let's hope that this one lasts a
bit longer.