This inverter has only been used once for testing by the previous buyer, so it is no longer brand new but is in excellent condition. The previous buyer returned it because they said it would not provide 800W. However, when I asked if they had the correct battery, heavy-duty cables, and proper setup required for the inverter to deliver that power, they said they did not. To achieve the expected performance, you must have: * A suitable 12V battery capable of supplying the required current. * Heavy-duty battery cables. * A proper fuse installed near the battery. * A correct installation and connection. Please make sure you have everything required before purchasing to ensure the inverter works as intended.