You need power

once you attach the base shield gen it will start drawing power.
but it will be slow, so you need shield upgrades. these are the "shield capacitor" and the "shield flux coil" the capacitor adds to the shields max hp but requires longer recharge time. this is wherte the flux coil comes in, the flux coil increases cunsumtion of power but increases recharge speed. im not fully sure but i think it decreases the shields max hp a bit