Any recommendations or advice on lightweight (compact) bike covers?

I keep my bike under a roof at home but I'm thinking about getting a cover that I can take with me to protect the bike when it's parked up while I'm out.

Something compact would be ideal, so it doesn't take up too much space in my pannier but weight is less of a concern since I put an electric motor on the bike. It won't be getting used every day either, so it wouldn't need to be bomb-proof. I'd like to keep the whole bike dry ideally but the biggest concern is keeping the battery and controller on my frame dry as I'm not sure how water-resistant they are.