Battery maintence during winter months

HI Everyone, first year with my Gem e820 with 6 new AGM batteries. Live in Colorado. Does not get super cold but we will get some cold nights that can hit 10°. I need suggestions on what is best way to maintain these batteries during winter months. Do I keep constant charger plug in at all times? Any suggestions would be appreciated!

The most important aspect of winter maintenance for AGM batteries is keeping them fully charged. Fully charge the batteries before winter storage. Use a smart charger or maintainer to keep the batteries topped off. You can leave the batteries connected to a maintainer throughout the winter.