[Suicide Junkie]

As a special case:
If your shields are up, but your ship takes damage through them, the CA ability will still boost shield strength.

EG: Phased Polaron Beams. If your shields are non-phased, and at 100/200 hitpoints, then if you get hit by a PPB for 50 damage, the CA on your ship can boost your shields up to 150/200 (Maximum boost is still the sum of the "shields from damage" amount, and shields never get boosted above 100%)

If you ram another ship, then your shields are not used in the collision. Assuming you survive the impact(!), and still have shield generators, your CA will again boost your shields.