Yeah, I got a real kick out of this one, and he was clearly enjoying being a bit biased.
I have a Ryobi 20" mower with a brushless mower and 3 94Whr batteries (or .094kWhr). Of which I can only use 1 at a time. They charge from empty in about 50 minutes, sometimes an hour, I suspect because they are so hot from having just come out of the mower. I have .6 acers maybe. The first mower I had was Ryobi's 16" brushed motor mower. It took 3 batteries just to do the front yard. If the grass is dry and its only been a week since I've mowed the 1 battery nearly does the whole front lawn, but its usually two. If its wet and tall, 3.