Stackable tower of power

I've been toying with an idea of creating a modular system of crates. Each crate is sized to snugly hold 2 robot batteries with a handle in the middle. These crates would stack on top of each other and be sturdy up to 4 crates high. We could keep robot batteries, battery chargers, extension cords, and power strips in them. Each crate could be handled by one person, or the stack could be moved with a hand truck.

Side view of 3 crates stacked up

sketches of the crate design.