I don't know if I would leave a trickle charger on a battery while away for an extended time. If one would go bad and no one is around to check on it hard telling what kind of damage you might have. JMHO. Remember, you get what you pay for.
I use the Battery Tender which has been very reliable. However I am able to check on it a few times a week.
1997 Triple E Empress, Freightliner Chassis, CAT 3126 w/ 275 horse's.
MD 3600 Tranny, 2011 Ford Escape Hybrid w/Blue Ox tow bar and Roadmaster Base Plate.
Amsoil Synthetic Oil only for my baby.