I believe you’re talking about a 3051. The slide is powered by the house batteries. If you disconnected the batteries they were not getting charged via the 30 amp connection.
I have that model and it’s always connected to shore power plus I never disconnect the batteries...too much stuff won’t work. I’m pretty sure driving will not charge them.
2018 Forester 3051S (aka Clyde)
2015 Wrangler Toad (aka Bonnie)
At some point during every day you suddenly realize nothing else productive is going to happen the rest of that day. For me, it usually occurs around 9 am.