If it is not behind a little hatch in the pillar, it is behind a hatch under the bathroom sink.
The solar always charges the AGMs, whether the battery switch is on or off. (I love my solar)
I'm not sure about when it is plugged in. If I'm in the van for a trip, the first thing I do is turn on the battery switch... and before I plug in, I turn on the inverter. When I unplug, I turn off the inverter. And when I am unloading the van when I get home, I finally turn off the battery... and the solar keeps my batteries topped up.
2019 Roadtrek Simplicity SRT (almost a Zion)
2015 Roadtrek 170
2011 LTV Libero
2004 GWV Classic Supreme