Tripp Lite PowerVerter APS1250 - DC to AC power inverter - 12 V - 1.25 kW - 2 output connector(s) - Canada, United States

Expensive, especially making the step to the 1250w version, but worth it for the peace of mind when using it as a ups for a sump pump. The larger version easily powers our 1/2hp sump pump and is backed by 2 Valence LiFePo4 105ah batteries left over after upgrading our RV. Using the dip settings that battleborn gives for lithium batteries it seems to charge fine to full capacity as reported by the Valence app. In some short tests it looks like we should be able to ride out extended power outages of several days before the batteries are depleted.