Deltec? Not B but maybe? I have a small Deltec which didn't do much when power went out running pumps on AC, Alarm would come on and power shut down. iCon if you have DC pumps, Costco has online a solar panel that can maintain charge on an automotive/marine battery; is not small nor huge but might provide peace of mind. Solar panel on the roof, battery crawl space and wall fish the connection for the back-up power supply.