I have a Mikita 12V battery powered drill that I absolutely love. It's older, obviously, being 12V, but it works perfectly...except for crap battery support.
A few years back, when I needed a new battery, I hit up Amazon and bought a generic, which worked great. This repeated again, and good results again. The batteries last maybe 3-5 years.
Earlier this year, it was battery time again so I ordered an Amazon generic, and it was junk. Returned them (two pack) and bought a different brand...and junk again. A real deal Mikita battery costs $100, and a new Makita drill is same...so can't see spending that much for a battery.
In the end, I wound up buying a new Milwaukee drill. It cost me quite a bit, but it came with two batteries, which I'm sharing with other tools.
This left a bad taste in my mouth, and overshadowed ideas of an electric lawn mower purchase. I don't even want to know how much a high powered lawn mower battery will cost. Plus, all the electric mowers I've seen are "plastic fantastic", which doesn't sit well on a machine that's going to be used hard and stored on the porch.
So, I bought gasoline. Hate me if you wish, but this machine will, hopefully, be the last I ever buy.