Nope. Damp rag, rinsed often in a bucket of water. Single trails are closed after rain, so it never gets really muddy. Probably looks odd, but I carry the bike over a couple of streams out there too. My theory, water and electricity don't mix.
Lightly damp rag here too for most of the bike. Cassette is cleaned with MUCoff and associated tools. Chain is cleaned with a sponge and a light brush. For the really grimy stuff you can use some soapy water just as long as it’s far away from the electrics.
Battery off the bike, there's no chance to short the system even if a drop or two of water get's into a connection.
Battery mounted, the system will be looking for that opportunity.
I live in the arid west and a bucket wash is the right way to do it with the battery off the bike.