The disconnect switch had nothing to do with dry batteries. Did you add the water to the batteries or did the dealer? How much water was added?When you say dry we assume you mean low, how low? Was the water level below the plates? or just to the top of the plates? I would put a voltmeter on the batteries with the charger plugged in and record your voltage at the battery terminals. Should be between 14-14.6 volts depending on your charger and batteries if it is working correctly. Are your batteries 12 volts or 2 6 volt batteries in series? How old are your batteries? Based on your answers you my be able to recover these batteries.