A good thing about Black and Decker electric lawnmowers, at least mine,
model 875, is that the plastic cover has no holes where water can get on
the motor. AFAICT, if you leave it out during the rain, the wheels get
wet, and the switch on the handle gets wet, but the plastic cover covers
everything else.

I have a spare switch so if I remember, I'll check how waterproof that
is, but I'll bet it's pretty good.

Not that i know what this all means first hand. I've kept my mower
covered by a plastic cover and under the deck.

And I don't remember their advertising making any claims about this. If
true, I think it would be a big selling point. Esp. since most who buy
the mowers have small yards and not a lot of space to store them.