If you can unplug from power a day or two and your slides still work well afterward then the battery is probably still good. But a seemingly good battery that is nearing end of life can suddenly fail. Ever had a vehicle that always started fine until one day it didn’t? Batteries have a warranty period depending on the quality of the battery. Good idea to replace that battery before that time is up. The manufacturer knows about how long they are designed to last and then they set the warranty time accordingly.