Now I'm wondering about a cordless push mower. How much will it mow? I suggested a self propelled mower any ways. She's had both hips replaced already and is only 55. (Birth defect).
I have the 21" self-propelled Ego with the 7.5 amp hour battery that txdon mentioned. It's great for my yard, since I mow regularly. And it can mow fairly tall stuff, too, but if it's tall AND thick, and you're trying to cut it real short . . . well, the battery can run down pretty quickly and/or the mower will shut down from overheating. Of course, you wait a couple of minutes and it'll go again. I just finished working on a neighbor's yard, and it's a mess.
The mower comes with the bagger and the chute plug to make it a mulching mower. If you want the side discharge chute, you can request it from the company and they'll send you one at no charge. I've got it, and it's worth just about as much as I paid for it. It just constantly clogs up and you have to keep stopping to unplug it. It's much easier and faster to bag the clippings and just dump them.
Under normal conditions, I can mow all of our yard, the neighbor's front yard and three-fourths of his back yard before I have to change the 7.5 battery for one of my 2.5 batteries to finish the job. But IF it's heavier mowing, the battery will run down quicker. All I was mowing this afternoon was the neighbor's back yard and I didn't even finish that before that 7.5 battery ran down.
Incidentally, the self-propelled feature is controlled with a separate lever on the handle. You can push it and mow without using the self-propulsion. You can also use the self-propulsion without engaging the blade.