This really needs to be changed. AI should always when fighting a player deploy all his ships, but also cheat a little so he doesnt lose in huge amount CR
I cannot really agree with this sentiment. The computer should deploy an appropriate force for each engagement, plus some margin of superiority ideally dependent upon how safe the fleet feels, how much it needs to conserve supplies, faction wealth, faction power, and faction standard response levels. No one in their right mind should be deploying fleets of battleships to engage a handful of light ships that the destroyer screen should be able to deal with. If the screening light ships have trouble dealing with a small group of light ships, that's when the big ships should start coming into play. By the same token, an attack by heavy ships ought to be met by a similarly powerful force of heavy ships and supporting lighter vessels, if available.
It should also ideally depend on how well-known (or leveled) the player happens to be - some level 1 nobody in a frigate attacking a Hegemony System Defense Fleet might only draw a destroyer and a couple of frigates to deal with the nuisance. A level 30 character in a frigate who has a reputation for going after and taking down System Defense Fleets might be worth a much stronger initial response.