Pausan wrote:
We got home and I didn't plug the camper in for a week or so and the batteries were still powering things fine - really have only used the lights. Last night I checked the batteries - the water level was fine and there was wetness on the tops and rusty spots on the bottom of the box again.
This would mean that the moisture is not a result of charging the batteries. I think what you're experiencing is condensation within the box. Depending on the environmental conditions, there may be little you can do to prevent the moisture. Maybe some desiccant would help.
You may be able to reduce the maintenance of the box (i.e. less cleanup) by thoroughly washing the battery case and using one of these
Acid neutralizing pads.