The telecommunication and data communication businesses are experiencing strong growth and so is the demand for batteries for back-up power. The stationary lead-acid battery is the type that dominates these applications. This presentation will give some guidelines for battery scientists who want to apply their technology to back-up power. The opinion of the author is that the advanced batteries that are in the frontline today are poorly adapted to the needs of back-up power for networks. If developers of these advanced batteries are to stand a chance of achieving success in the network power market they must focus on reliability, volumetric energy density and cost.