I have a 325W panel on the roof of my RV. At some time I may want to park the RV in the shade and set out a suitcase solar panel. For the roof panel, I have a Victron controller and an inline fuse to disconnect it. My question is: If I get a Renogy suitcase with its own controller and want to alligator clip it to my two lithium batteries, is charging from the rooftop or the suitcase an either/or proposition? Are there other options, such as getting a suitcase panel without its own controller and connect to my Victron to control it? Thanks
The lithium batteries won't care they'll suck up whatever juice you give them. I have dual 40 amp solar charge controllers in my rig for two separate solar rooftop arrays and oftentimes have a DC-DC charger or converter charger running at the same time. Slight differences in voltages can reduce the total amps somewhat versus a single charge source but nothing is harmed.
My solar controllers are set at the default lithium setting for 14.2V and the other chargers are14.4V. But the main difference will be wire lengths causing voltage drops. Your suitcase controller will likely have a longer run so it may get tricked into thinking the batteries are full and back off its charging amps. You can always tweak settings for the max charging levels.