Seasonal camping battery question

13V won't hurt it. Check your electrolyte levels every couple of months.

Hmm some say remove and some say leave it. Lol its around 13 volts at the battery when it's plug in. I guess I'll leave it in and hope for the best. Thx

We're summer seasonal and have been for many years, I've never removed batteries from any rv that we've had. I just check the water level about every 3 months; usually need to be topped off after 6 months (not much). No issues when we're ready to roll in the fall.

The Elixir ELX series are low quality single stage converters. They are not good for the battery. The good news is that they can operate without a battery connected.

The ELX-45 is a single stage converter. Constant voltage output. I know, I had one in the last HTT.
I'd remove the battery.

What is the voltage on the battery terminals?

Nope. you won't hurt it, and there are "some" RVs that need the battery installed to complete the circuit to make the 12V system work. your lights run off 12V, even when hooked to shore power.