removing batteries for winter.

Bill, it might be your charger in your converter. My first Iota converter didn't have module to switch down to trickle charge (Keystone too cheap), and it would boil off the batteries. I had to install the module myself, which was real simple and no problem after that. This PD converter does have the rate charge and is selectable from front in my breaker box. I can select trickle, or several other step down charges.

You might check that. The alternative might be to just charge the batteries direct off a smart battery maintenance charger and disconnect from the trailer, but leave the batteries in place.