I don't do much riding after Thanksgiving, and have a GS and scoot, but just one charger. Some battery chargers like the Battery Tender Jr. will do an "exercise" program now and then. Do you think they'd get confused if left connected to two batteries at the same time (two bikes, jumper-cabled together)?
Probably.
I don't understand the principle of operation on some of the new "electronic condition monitoring" battery chargers. In theory, it should only see it as a larger battery, but I suspect if the batteries are different sizes it may confuse it.
Wal Mart sells a 1.5 amp automatic trickle charger for about $20 as I recall. I plug my GS in every night during the winter, as my heated gear takes a toll on the battery charge.
Thanks, GeeP, the two batteries are pretty close to the same size. I think I upped the GS to 1.5Ahr, and the scoot is 1.0.