This product has saved me a few freezer and refrigerators full of food over the years plus allowing a few lights to still shine in my house.  At a very reasonable price!!!  When these incidents happened, I simply backed my car out of the garage, connected the cables to the car battery, and ran an extension cord into my house.  As long as the cart was running in idle, the power flowed.   This product was purchased at Harbor Freight and always worked.