Thanks!
I read the manual to my Blizzard card yesterday, and there was not much about the battery. I said though that, if the computer was turned off, for more than six weeks, the battery would not hold the savings anymore. And it also said that you have to have the computer on for at least four hours, and then at least two hours per day for a week, for the battery to charge completely.
So I tried to have my A1200 on the whole night and then I turned it off. When I booted up again the date and time was still there.
Amazing that the battery still seems to be working. I bought the Blizzard 1994 or 1995 I think. That's 10 years of operating. Amazing.... :-)
/Jörgen