Anyone keep their B plugged in for winter storage?

I have wondered about this also. My 1988 xplorer has the original converter. I can see on my battery monitor it is charging when plugged in. ( a dash mounted volt meter I installed) But this old converter seems to charge at a fairly high rate. It's probably not a maintainer. I sure don't want to cook the battery. Should I put it on a timer like one poster said? It's really cold here in N E. Illinois.