First we need to know whether your slide operation system is electric or hydraulic. As "fonzie" stated--the slide should operate using only battery power, whether electric or hydraulic. "tsattwoo" states that his/her lights work on battery only, but--the battery may have enough power to operate the lights (probably for a short time) but not enough power to operate a high current draw such as a slide unit. After having to replace my deep cycle battery twice within twelve months I found out that the inverter/charging system was burning my batteries up. Even though the paperwork with my new inverter stated that it had a battery monitor system built in and would not allow a battery to overcharge--yeah, right. I put a battery disconnect on my unit and try hard to remember to disconnect my battery when the unit is parked at home. So "tsattwoo" your battery may have enough power to operate the lights, but for how long? And your battery may be just weak enough that it will not operate the slide.