Great, its Christmas morning, you excitedly unwrap you present. It's a new container ship! Then you read the dreaded phrase on the box: "Batteries not included. Requures 10 container batteries". You rummage around in the odds-and-ends draw in the kitchen (we've all got one), but you can only find 9. Christmas is ruined.

ETA: This is actually a very cool design. Being able to swap the batteries with normal cargo handling facilities will be a huge boon and keep these ships moving.