The DeWalt G89101 is a Tools system that requires a 12V 18Ah AGM replacement battery. The compatible Universal Power Group replacement is the UPG UB12180 12V 18AH T4 AGM Battery (UB12180), a 12V 18Ah AGM sealed lead-acid battery. It uses T4 terminals. This is a direct drop-in replacement for the DeWalt G89101 requiring no modification to the device.
