My super delight spend most of the last 4 days with batteries removed outside on the bike rack in steady rain. We were traveling and there just wasn't an optionI for indoor or covered storage. I was worried and so went out to watch, and oddly, no water accumulated in the upper battery bay. If you look at it, the electrical connections are at the top of the upper bay so they stay relatively out of the wet and as it turns out the water that did get into the bay drains out pretty successfully from a small hole at the back of the battery bay the empties into the seat post tube and then out just above the rear shock. So, long story, I am much less worried about the bike being out in the wet than ai was. I should note that after a hard rain one night we loaded the bikes up, reinstalled the batteries and had a nice uneventful ride. I am pretty sure the Bosch motor is well sealed and the only concern I have is the possibility of some connector corrosion some time down the line. All in all I am a lot more comfortable transporting and using the bike in wet circumstances.