Battery power module dimensions

It looks very weird that the power modules of 1.5m batteries only take up about 1/6 of the battery volume. I would expect most of a battery to be power storage, with relatively little supporting structure. It would make sense to put the power module port on the 1.5x1.5m side and have it connect to a large conveyor instead of a small one (when conveyoring for batteries becomes a thing), with the power modules themselves being slightly smaller than the full 1.5x1.5x1.5m volume; the 2.5m batteries could have the power module ports on different faces (yes, that will not work out well geometrically in the middle of the block, but we can suspend disbelief).

Alternatively, the 1.5m battery could have four or six small-conveyor ports instead of just one, and each power module would hold 1/4 or 1/6 of the current module's capacity respectively. This way most of the battery's volume will be, well, battery, while it will be clear how the 1.5m and 2.5m capacities are so much bigger than the 0.5m batteries, despite power cells and power modules being relatively similar sizes.

To be fair, a 1x1x1m or 1x1x1.5m power module volume (taking up about 2/3 of a 1.5m battery) would seem like a better battery-to-power-module ratio, but there are no 1x1m conveyors.