We are also satisfied Patriot users. Have just one unit, but used on two toads.
To answer the charging question, YES, it will charge without being "on." You will want it to be fully charged before you head out on the road.
Ken & Deb (WIT Club, FMCA, SKP, Harvest Hosts, and grateful volunteers with SOWERs)
2005 Winnebago Vectra 40FD w/400ISL and Allison 3000MH on Freightliner's Evolution chassis, Onan QD7500, 1000w Renogy solar, BlueOx tow gear, and 2015 Cherokee TrailHawk toad.