1. Slides ALWAYS Operate from the batteries. The majority operate from the COACH batteries
2. Some slides require either the Shore or Genset to be connected to get optimum 12 volt power for the slide function
3. The REASON your batteries showed bulk charge is because EVERYTIME 120 power is supplied to the Inverter/Charger, (regardless of how long it was connected), the Inverter/Charger goes to BULK charge mode, then "tests" the batteries for a few minutes and then goes to Float(absorbsion) charge if the batteries are at almost full charge. If they are depleted, then it stays in BULK until it determines the state of charge to then go to Float.
4. IF your batteries were fully charged and you have 2 or more batteries on that bank, and the slide stopped(I assume electric motor slide), then that indicates a failing slide motor that needs a little more voltage(from 12.6 to 13.2 or more) to operate correctly. Replace the slide motor now or experience complete failure down the line. Doug