There is a big difference between a charger and a smart charger. There is a big difference between a Battery Tender Jr. & a Battery Tender "Plus". For some reason folks still think BT is a generic name for both and they do the same thing. The "Plus" will never "boil over" you battery if you leave it on. The Jr. is a great charger but it is a regular-type that you should not leave on for extended periods. It's a charger, not a maintainer.
I'll be starting my old r60/2 today as it has been buried in the back of the garage all Winter and it has been on a "Plus" since November. Started occasionally but never off the charger.
Same for the 5 years I've owned that bike.