Seems like you’d use more than a half a gallon to mow an acre with a gas push mower.Yes, this is my wife's mower. Takes a little more than 1/2 gallon to charge the battery to full using my least efficient generator. A full battery will mow half the yard. (I live in the farms on 2 wooded acres)
Next I'll try charging it with the very efficient (40%) Diesel Listeroid generator. Guessing less than 1/4 gallon diesel fuel.
By way of comparison, my commercial Snapper mower will do the yard with less than a tank. Holds about 20 ounces.