Basic battery charging and solar question

Boins wrote:
The RV dealer told me that when I'm plugged in to charge, the trailer doesn't recognize when the batteries are fully charged and will keep charging.

Bad converter or incompetent dealer. Check the voltage, converter may or may not need replacement.

Boins wrote:
If the trailer does over charge, what is a simple option to create an automatic cut off once the batteries are charged.

Decent converter or Trik-L-Charge.

Boins wrote:
Is there a simple solar setup that just gives a trickle charge to the batteries while camping? I'm not expecting a solar setup that does a fast recharge, just a trickle.

Renogy 100W suitcase is simple. It does what can be described as trickle charging (and a little more). No worries about cut-off, this will happen "automatically" every night, and its output amps are low anyway. IMO, not too cheap for what it offers.

"Fast" vs "trickle" - you should read up on 3-stage charging. Small solar isn't fast but high amps don't necessarily mean fast either, because at some point the battery becomes fed up and stops accepting high amps.

The bottom line is - fast recharge from 50% to 100% doesn't exist. People with generators charge it to 70-80% and call it a day. Then they charge it fully on shore power.