Portable and Salvageable Power Cells: One solution for Two Common Requests.
Two common requests I've seen in my time playing SE are "something like a bottle for energy" and "I wish I could salvage power cells." In the current game, power cells cannot be salvaged because batteries have some charge when constructed, which allows for exploit. Battery cells starting with some charge is great for quality of life when building new ships, especially now that reactors are locked behind progression. My suggestion maintains this standard of living, while allowing powercells to be salvaged without exploitation.
Power cells behave like bottles, and batteries like O2/H2 generator.
Bear with me, I know it sounds radical. Nothing I'm about to suggest should effect gameplay in any way, except for the aspects it attempts to address.
The basic idea is for Power Cells to behave similar to bottles. They can be "charged" from 0 - 100% but are at 0% when created. Instead of being a component, Batteries have an inventory that exclusively holds Power Cells (Power Cells could be placed in said inventory when welded to preserve QoL.) Battery stats are dependent on # of power cells (a Battery with 50% of it's cells can only hold 50% as much energy, input/output 50%, etc.) When a new Power Cell is placed in the Battery, charge is balanced across all cells instantly (similar, but in contrast to how bottles are filled instantly) so that every Power Cell doesn't need to be calculated individually all the time. New batteries could be completed without Power Cells and charged by filling them with pre-charged cells, negating the need for batteries to magically start their life with energy. This would be too tedious to be the preferred method of charging, but provides utility since it doesn't require connectors. Since Power Cells begin with 0% it also wouldn't be exploitable. Batteries would need some form of interface for adding/removing Power Cells. The Interior Turret provides some precedent for an inventory access that isn't a conveyor port. Just pick a spot on the existing model to highlight and interact with. For example, the warning label on the Small Battery that looks vaguely like the cover on a breaker box (It doesn't have to make sense. The Interior Turret's doesn't, if you think about it.)
This is a better solution for the energy exploit because it doesn't violate conservation, and it fulfills one of the more common requests I've seen.