Winter temperatures require higher float voltages, something no converter that I know of does.
My AGm specs float voltage of 13.6.
If I fully charge it, determined by amperage at absortpion voltage, then float it at 13.5v at 60F overnight. In the morning, when I bump up voltage back to 14.4v+ the amperage it accepts indicate that it somehow discharged slightly with the lower than ideal float voltage.
I'd want the batteries disconnected, periodically charged, not floated continuously at a set 13.2v.
Self disharge of batteries slows considerably in lower battery temperatures, but older batteries that were refilled with impure water might have a high enough self discharge to not make it through winter above 80%, presuming they were put away and disconnected at 100%.
Anyway unless the float/maintenance charger has temperature compensation, i would not leave it plugged in all winter long unless winter averaged within 15F of 77F.
And the Wfco is not to be trusted in any temperatures, imo.
