The Minuteman EN900 is a UPS system that requires a 12V, 8Ah replacement battery. The compatible Universal Power Group replacement is the UPG UB1280F2 12V 8AH F2 AGM Battery (part number UB1280F2). This battery delivers up to 96 watts of standby power. It weighs 4.74 lb, uses F2 terminals, measures 5.94 L x 3.7 H in, and has right polarity. This is a direct drop-in replacement for the Minuteman EN900 requiring no modification to the device.
