I cant answer your egg question as I havent gotten the opportunity to breed yet but I do have my racks and soon to be incubator hooked up to a back up battery made for giant business computer servers. Everything runs through the battery and when power is cut it automatically starts delivering power. Mine beeps when it starts to run which lets me know that the power is out or one of my cords is unplugged. I havent had to use this for more than an hour or so but I was told it should be able to keep my racks/incubator powered up for a couple days b/c flexwatt doesnt take too much power to run. My backup is made by APC(American Power Conversion) in case you're interested.