510AH but it's not in the camper 😉
I put two 100AH Vetarer batteries in the battery box (those are the heated batteries) and my first test was done with a 100AH Redodo battery and a Redodo DC to DC charger hooked up to the aux solar input. Worked like a charm (I can share that video if allowed here?).
Next, I looked at the space in front of the wheel well of the truck and realized I could place mu 310AH XZNY battery there if I placed it in a box and tied it down. I could then run the DC charger either to the camper to provide 600w of 'solar charging' off the battery, or to the truck to charge the battery 😉
I suspect what I will settle on is a small 30A MPPT controller at the solar input wired to the battery and the DC charger wired to the truck and charging the battery - this will also allow me to add 600w of solar since the Redodo has a solar input as well (it's an MPPT controller as well as a DC charger -- neat little unit).
I'm a youtuber (and long time RV net user though I was gone a couple years -- very busy on YT) and make videos about doing these things.