I know the games are not a very good source, but they're my only source for how shields are handled on ships. In the games, you'd start with 100%, but you could charge up to 200% full front/rear, and then not be able to go above that point on either end. This required dumping extra energy to shields to go above the initial level, otherwise you could freely reallocate the 100% between front and back. I don't know if that was based on references from the books, or a completely fabricated game mechanic, but the only real difference between that and FS default is that in FS you start with the full '200%'. We could easily imitate the current behaviour by starting all ships at half shields and making it so that at default shield energy there's no recharge I think. But, I'm not sure it's worth it, because FS already does a pretty good job of imitating the Star Wars feel, or I've always thought anyway. In fact, I've always considered the freespace series a spiritual successor to the Lucasarts games, since the mechanics are so similar.