Hiya Tom,
Yup, perhaps an unfortunate choice of words what with batteries & charge memory!
Anyways, agreed, if not using the bike best to isolate the battery completely: if the blurb is to be believed they'll go a year with no appreciable discharge.
I too only have a good old fashioned car charger... and will use this if necessary. One other possible thought is my multi battery type / voltage electric RC Heli charger - a fancy bit of kit & in all likelihood adaptable - given a bit if research. Better informed comments on this out there pls?
Cheers,
Simon